Addressing the Motorcyclist Advisory Council Recommendations: Synthesis on Barrier Design for Motorcyclists Safety

Photo: Texas A&M Transportation Institute

Addressing the Motorcyclist

Advisory Council Recommendations:

Synthesis on Barrier

Design for Motorcyclist Safety

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Technical Documentation Page

1. Report No.

FHWA-SA-21-069

2. Government Accession No.

3. Recipient's Catalog No.

4. Title and Subtitle

Addressing the Motorcyclist Advisory Council Recommendations: Synthesis on

Barrier Design for Motorcyclists Safety

5. Report Date

May 2021

6. Performing Organization Code

7. Author(s)

Chiara Silvestri-Dobrovolny, Georgene Geary, Karen Dixon, Michael Manser,

Jayveersinh Chauhan

8. Performing Organization Report No.

9. Performing Organization Name and Address

Texas A&M Transportation Institute

The Texas A&M University System

College Station, Texas 77843-3135

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

693JJ320D000023

12. Sponsoring Agency Name and Address

U.S. Department of Transportation

Federal Highway Administration

Office of Safety

1200 New Jersey Avenue, SE

Washington, DC 20590

13. Type of Report and Period Covered

Final Report

14. Sponsoring Agency Code

15. Supplementary Notes

Task Order Manager for this report is Guan Xu.

Project Title: Addressing the Motorcyclist Advisory Council Recommendations

16. Abstract

The purpose of roadside barrier systems is to reduce the severity of injuries and number of fatalities by controlling and mitigating

crash forces. While barrier systems have been designed and proven to be beneficial for motor vehicles they do not currently

address the problems associated with motorcycle crashes. This synthesis of research presented in this report concludes that

motorcyclists are more vulnerable than drivers of motor vehicles and that motorcyclists are more likely to be severely injured when

they crash into a barrier system. Addressing the challenges associated with barrier systems is critical for reducing the severity of

injurious and number of fatalities associated with motorcyclist-barrier crashes. The synthesis report summarized several new

barriers and retrofit systems currently used or under development that are specifically intended to improve motorcyclist safety in

addition to retaining the existing benefit for motor vehicles. This synthesis report identifies current research proposals and research

gaps that should be considered for future research projects. A significant gap is the lack of testing standards and protocols in the

United States to verify the safety advantages of roadside barriers for motorcyclists. The final portion of this report summarizes

testing parameters to be considered for both upright and sliding impacts into roadside safety barriers that should be investigated

during the planning, development, and research of testing standards in the United States.

17. Key Words

Motorcycle safety, barriers, barrier design

18. Distribution Statement

No restrictions. This document is available to the public through

the National Technical Information Service Alexandria, Virginia

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19. Security Classif.(of this report)

Unclassified

20. Security Classif.(of this page)

Unclassified

21. No. of Pages

22. Price

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized

iii

TABLE OF CONTENTS

TABLE OF CONTENTS ............................................................................................................ iii

LIST OF FIGURES ...................................................................................................................... v

LIST OF TABLES ....................................................................................................................... vi

LIST OF ABBREVIATIONS AND ACRONYMS .................................................................. vii

Chapter 1. Introduction................................................................................................................ 1

Motorcycle Safety Considerations .............................................................................................. 1

Motorcycle Crashes ............................................................................................................ 1

Motorcycle-Barrier Crashes ................................................................................................ 2

Chapter Concluding Comments .................................................................................................. 5

Chapter 2. Roadside Barriers and Motorcycles ......................................................................... 6

Contrasting Motorcyclist Fatalities and Injuries Based on Barrier Types .................................. 7

U.S. Studies Related to Barrier Type .................................................................................. 8

European and other Non U.S. Studies Related to Barrier Type .......................................... 9

Motorcycle Riders Injuries Related to Barrier Crashes .................................................... 10

Barrier Types and Motorcycles ................................................................................................. 10

Rigid Barriers .................................................................................................................... 11

Semi-Rigid Guardrail Systems ......................................................................................... 16

Flexible Cable Barriers ..................................................................................................... 26

Signposts ........................................................................................................................... 28

In-Service Performance Evaluations (ISPE) ............................................................................. 29

Cost and implementation .......................................................................................................... 29

Chapter Concluding Comments ................................................................................................ 31

Chapter 3. Next Steps and Possible Future Activites .............................................................. 32

Current Problem Statements ..................................................................................................... 32

Development of Guidance for Enhanced Delineation of Barriers and other Roadside

Safety Hardware, Slopes, and Obstacles to Improve Visibility for Motorcycles. ............ 32

Factors Contributing to Injurious and Fatal Motorcycle Crashes with Traffic Barriers ... 33

Potential Research Topics ......................................................................................................... 33

Development of a Motorcycle Testing Standard Addressing Motorcycle Testing and

Impact Configurations in the U.S. .................................................................................... 34

Research Examining In-Service Performance Evaluation ................................................ 34

Identification of Critical Locations to Implement Barrier Systems .................................. 35

Enhance the HSIS Database with information on Motorcycle Protection System Barriers

and additional Motorcycle Crash Data ............................................................................. 36

Testing Standards and Protocols ............................................................................................... 36

Existing Standards and Protocols...................................................................................... 37

Development of New U.S. Standards and Protocols ........................................................ 40

Finite Element Analysis and Simulation .................................................................................. 43

Conclusion ................................................................................................................................... 46

Acknowledgments ....................................................................................................................... 48

References .................................................................................................................................... 49

LIST OF FIGURES

Figure 1. Example of a Concrete (rigid) Barrier. ............................................................................ 6

Figure 2. Example of a Guardrail with Steel Posts. ........................................................................ 6

Figure 3. Example of Cable Barrier. ............................................................................................... 7

Figure 4. Rigid Concrete Barrier. ................................................................................................. 12

Figure 5. Example of Simulated Motorcylist Impact With a Concrete Barrier. ........................... 13

Figure 6. Design of Retrofitted U-Shape Post with Barrier. ......................................................... 14

Figure 7. Tested Retrofitted Design on the Test Site. ................................................................... 14

Figure 8. Sequential Images of Crash Test of a Motorcycle into a Fence. ................................... 16

Figure 9. Semi-Rigid Midwest Guardrail System. ........................................................................ 17

Figure 10. Impact of Anthropomorphic Test Device into Discrete Post. ..................................... 18

Figure 11. Crash Test Simulation with Continuous MPS to Address Sliding Motorcyclist

Impact with Discrete Posts. ............................................................................................... 19

Figure 12. Illustration of Retrofitted Guardrail. ............................................................................ 21

Figure 13. Back View of Fabric MPS. .......................................................................................... 22

Figure 14. Front View of Fabric MPS. ......................................................................................... 23

Figure 15. Motorcyclist Impacting the Rail and Discrete Posts of a Guardrail System. .............. 24

Figure 16. ATD Sliding Along the Top of a TxDOT MPS in a Texas A&M

Transportation Institute Crash Test (Dobrovolny et al., 2019). ........................................ 26

Figure 17. Flexible Barrier – Cable Rope Barrier. ........................................................................ 27

Figure 18. Depiction of the 'Nelson Comb'. .................................................................................. 28

Figure 19. Discrete Sign Post System. .......................................................................................... 28

Figure 20. Finite Element Computer Model Developed by Schulz et al. (2016). ....................... 44

LIST OF TABLES

Table 1. Upright Impact Configuration Evaluation Parameters, Selection Rational, and

Additional Considerations for Upright Motorcycle Testing and Evaluation

Standard and Protocols. .................................................................................................... 41

vii

LIST OF ABBREVIATIONS AND ACRONYMS

AASHTO American Association of State Highway and Transportation Officials

AIS Abbreviated Injury Scale

ATD Anthropomorphic Test Device

CALTRANS California Department of Transportation

CBP Crash Barrier Protection

CDC Center for Disease Control

CEN Comité Européen de Normalisation (European Committee for Standardization)

CODES Crash Outcome Data Evaluation Systems

CRIS Crash Records Information System (for Texas)

FARS Fatality Analysis Reporting System

FHWA Federal Highway Administration

FSI Fatal-Serious-Injury Ratio

GES General Estimates System

GIDAS German In‐Depth Accident Study

HIC Head Injury Criteria

ISO International Organization for Standardization

ISPE In-Service Performance Evaluation

LIER Laboratoire d'essais INRETS Equipment de la Route

MASH Manual for Assessing Safety Hardware

MAC Motorcyclist Advisory Council

MC Motorcycle

MGS Midwest Guardrail System

MPS Motorcycle Protection System

MUTCD Manual of Uniform Traffic Control Devices

NCDOT North Carolina Department of Transportation

NHS National Highway System

NHTSA National Highway Traffic Safety Administration

NSW New South Wales

OV Opposing Vehicle

PDO Property Damage Only

RDG Roadside Design Guide

SMV Single Motor Vehicle

TTI Texas A&M Transportation Institute

TxDOT Texas Department of Transportation

UDOT Utah Department of Transportation

UNE Una Norma Española (Spanish Association for Standardization)

CHAPTER 1. INTRODUCTION

The design, construction, maintenance, and retrofit of roadway facilities requires an inclusive

approach that considers the interactions between a vehicle and the roadway. This approach is

essential so that the facility can provide the safest possible driving environment. As part of this

balanced approach, there is a need to comprehensively understand how the candidate design

vehicle characteristics may differ and how these differences can be expected to influence vehicle

operations on the roadway. Historically, the typical design vehicle primarily considered for road

design has been the passenger car. In some cases, a heavy vehicle may have also been considered

when weighing issues such as acceleration from a stopped condition. Unfortunately, the direct

inclusion of motorcycles as potential design vehicles has been limited.

MOTORCYCLE SAFETY CONSIDERATIONS

To consider fully how to best accommodate motorcycle safety, there is a need to first assess the

nature of this issue by contrasting motorcycle crash statistics to those of other road users. This

information can then be used to help leverage ways to better address issues unique to motorcycle

crash characteristics.

Motorcycle Crashes

The examination of crash statistics highlights the need for more direct inclusion of motorcycle-

related considerations and how these challenges can be addressed as part of the roadway project

development process. More than 14 percent of fatalities in the United States (U.S.) are attributed

to motorcyclists (NHTSA, 2017), yet motorcycles make up only three percent of registered

vehicles and only 0.6 percent of vehicle miles traveled (NHTSA, 2017). Based on a U.S. study

conducted in 2019 using data acquired from the Fatality Analysis Reporting System (FARS) and

the General Estimates System (GES), there were 5,172 motorcyclists killed in 2017 (NHTSA,

2019). These statistics demonstrate that motorcyclists have a greater likelihood of being involved

in a fatal or serious injury crash when compared to passenger cars. Because a motorcycle is one

of the most vulnerable motor vehicles on the road, there is a clear need to provide targeted

research to determine ways to safely accommodate motorcycles and reduce crash severity

associated with these vehicles.

A recent study conducted by the Federal Highway Administration (FHWA) reported that there

was a 34 percent decrease in the number of passenger car and light truck fatalities between 1994

and 2014 (Nazemetz et al., 2019). In that same timeframe motorcyclist fatalities doubled

(Nazemetz et al., 2019). These findings indicate that although measures have been taken to

improve safety overall for motorists in the past 20 years, safety specific to motorcyclists appears

to have been overlooked. Of course, the number of motorcyclist fatalities are much smaller as

they make up a small percent of the total motoring public. These trends are disconcerting.

NHTSA data shows that overall motorcyclists are 37 times more likely to be killed than car

occupants per distance traveled (NHTSA, 2008).

European transportation agencies have also recognized the need to address motorcycle safety.

Research from 23,000 crashes in the United Kingdom indicated that motorcyclists were more

vulnerable than passenger car occupants with a 15 times greater chance of being involved in a

fatal crash than that of a car occupant (Williams 2004). A 2018 European Commission study

indicated 15 percent of all road fatalities were motorcyclists. The data also showed that 11

motorcyclists per 100,000 registered two-wheelers were involved in a fatal crash compared to

five car drivers per 100,000 registered cars.

A study by Williams et al. (2008) analyzed information from 110 of the 278 police files relating

to fatal crashes as documented within the Transport Research Laboratory’s collection for pre-

impact motion of motorcycles. Based on the analysis by Williams et al., motorcyclists were the

most vulnerable road users observed in the study with a 27.2 percent fatality or serious injury

rate as compared to 12.8 percent for car occupants.

A study conducted by Frederickson and Sui (2015) used data from the German In-Depth

Accident Study (GIDAS) for the period 1999-2014. Frederickson and Sui compiled data for 3361

total motorcycle crashes and 79 fatal crashes in Dresden and Hanover. They identified that the

most common cause of injury for single vehicle motorcycle crashes involved hitting a guardrail

or a tree. The injuries related to fatal crashes involved 48 percent head injuries, 23 percent thorax

(chest), 10 percent spine, and 4 percent other.

Wilson et al. (2019) conducted a study to analyze Texas motorcycle crash data with a goal of

using their findings to further development of freeway ramp concrete barrier systems. The

authors attempted to identify relevant factors related to crashes in which a motorcycle impacted a

road safety barrier on flyover/connecters or on curves. Their analysis focused on the distribution

of fatal and incapacitating motorcycle injury crashes that occurred in Texas from the year 2014

to 2016. Wilson et al. reported that 40 percent of the observed injury crashes where a motorcycle

impacted a flyover or connector were fatal (leaving 60 percent to be classified as incapacitating).

For these fatal or injury crashes, 3 fatal and 6 incapacitating crashes resulted from an overturned

motorcycle. Guardrail, retaining walls, median barriers, and bridge rails were classified as the

harmful object struck for 3 to 4 fatal or incapacitating injury crashes. Locations with curvature

included 26 percent of the crashes resulting in fatalities with the remaining 74 percent resulting

in incapacitating injuries.

An effective approach to identifying ways to improve motorcycle safety is to analyze safety data

and determine how the areas of roadway geometrics, roadway construction and maintenance,

barrier design, pavement design and materials, and automated and connected vehicle

enhancements can collectively be improved to enhance motorcycle safety performance. This

report focuses on candidate roadside barrier safety performance as it relates to the motorcycle-

barrier crash condition.

Motorcycle-Barrier Crashes

The placement of a roadside barrier is intended to enhance roadside safety by minimizing the

likelihood that an errant vehicle will run off the road and impact a rigid obstacle such as a tree.

The barrier itself, if not installed correctly or as per roadside design guidelines recommend,

could in some cases cause more harm than the obstacle it is intended to shield. For this reason, it

is important to understand how a vehicle will respond upon impact with a roadside barrier.

An emerging concern is the effect of roadside barriers specific to motorcyclist safety. Barriers

represent a small proportion of all crashes, but there is a much greater risk of a fatality for

motorcyclists than for car occupants (15 times greater in Europe and 80 times for the steel

guardrail in the United States) (Grzebieta et al., 2013). A review by Nazemetz et al. (2019) of the

FHWA Motorcycle Crash Causation Study (MCCS) data of 351 crashes indicated that guardrail

and traffic sign supports were one of the most harmful motorcycle crash events. Data from a

soon to be released report for the NCHRP 22-26 study specifically looked at motorcycles and

barriers and found that in the US motorcycle-guardrails crashes are responsible for more fatal

crashes than any other vehicle-guardrail crash (Gabler, 2020). From 2001 through 2006, there

were a total of 1,462 cases of roadside fatalities that involved a motorcycle in Australia and New

Zealand with 78 of those cases positively identified as involving a roadside safety barrier

(Bambach et al., 2010).

The following sections in this chapter review the influence of motorcyclist positions associated

with a motorcycle-barrier crash and associated helmet use performance due to a motorcycle-

barrier collision. Chapter 2 of this report further identifies barrier types in greater detail and

provides a synthesis of their role in the safety performance of motorcycle-barrier crashes.

Common barrier systems include concrete barriers, guardrails (also sometimes referred to as

“guiderails”), and cable barriers. In addition, discrete barrier elements such as sign posts can be

obstacles when impacted by a motorcycle or motorcyclist. These roadside treatments are

typically constructed as safety enhancements to mitigate the injury to vehicle occupants, yet in

some cases they may create new safety risks for motorcyclists. To better understand these

potentials risks, there is a need to further examine the characteristic of these crashes as well as

understand the role that the motorcyclist’s position at the time of the crash and helmet use could

have on the overall crash condition.

Common Motorcyclist Position

Gabler (2007) reported that guardrail collisions (12 percent fatality risk) pose a greater risk for

motorcyclists than concrete barrier collisions (8 percent fatality risk). Similarly, research by

Daniello and Gabler (2011) suggests that motorcycle crashes into guardrail systems are reported

to be more harmful for riders when compared to crashes into concrete barriers. Based on the

position of the motorcyclist, motorcycle-barrier crashes that involved concrete barriers had more

instances of riders vaulting over the barrier. For collisions with guardrail, however, Daniello et

al. (2013) observed riders more frequently slid into the guardrail.

Vehicles can impact barriers at different angles and speeds and these impact positions can result

in different crash outcomes. Similarly, the method of impact into barriers by motorcyclists can be

different. Examples of ways in which motorcyclists may hit a barrier includes upright impact at

different angles, ejection from the motorcycle after striking a barrier, or sliding into a barrier. A

research study by Daniello et al. (2013) analyzed police reports to examine rider trajectories for

collisions that involved barriers in New Jersey between 2007 and 2011. The total number of

single-vehicle motorcycle-to-barrier collisions were 442 with 430 of those crashes analyzed and

the barriers identified for 342 of them. Barrier type was identified using Google Street View, as

barrier type in the crash reports was not always present or accurate. Motorcycles most often

(26.9 percent of the time) impacted a barrier while the motorcycle was in an upright position.

Crashes between motorcycles and barriers where the motorcyclist vaulted over the barrier

occurred 12.2 percent of the time, while crashes where the motorcyclist slid into the barrier

occurred 16.6 percent of the time. Crashes in which a rider was ejected from a motorcycle after

colliding with a barrier were 2.91 times more likely to have a serious injury than crashes in

which a rider struck upright and was not separated from a motorcycle. Also, if a rider was

ejected into a barrier then there was an increased chance of serious injury (4.73 times as likely to

be seriously injured).

Data extracted from a database that extended across England, Scotland, and Wales for the years

1992 to 2005 included 110 fatal motorcycle-guardrail related crashes with sufficient data for

analysis. In 58 of the 110 crashes, the motorcyclist was upright when he or she hit the barrier,

and the majority of the upright crashes involved the rail and not a post. In the 33 crashes that

involved sliding, the motorcyclists were more likely to have struck a post first instead of the rail.

In the remaining fatal crashes, the analysts were not able to determine the location of the rider at

impact (Williams 2008).

This research suggests that motorcyclist riding position upon impact with a barrier can influence

the type of injury sustained; however, injury type is not perfectly correlated with riding position

upon impact and, in fact, there are injury types that are prevalent across different impact riding

positions. As an example, Williams et al. (2008) concluded that regardless of the first barrier

element in contact with a motorcyclist during an impact, head injuries and severe injuries were

represented as the most common cause of motorcycle crash fatalities. Bambach et al. (2012)

provided a case series analysis study conducted with crash data from Australia and New Zealand

of motorcyclists who were fatally injured following a collision with a roadside barrier from 2001

to 2006. The thorax region had the highest incident of injury followed by the head region

(Bambach et al., 2012). In fatal motorcycle crashes in single and multi-vehicle crash modes, head

injuries predominated all other injuries. The injury profiles were similar with motorcyclists that

slid into a barrier or collided with a barrier in an upright position.

Helmet Use

Based on information provided by the Centers for Disease Control and Prevention (CDC),

helmets are an important and proven protection device. NHTSA (2019) estimated that

motorcycle helmets helped save the lives of 1872 motorcyclists in 2017. NHTSA further

estimated that helmets reduced the likelihood of fatal injury by 37 percent for motorcycle riders

and 41 percent for their passengers. Additionally, research by Derrick and Faucher (2009) and

Liu et al. (2008) determined that helmets reduced the risk of a head injury by 69 percent.

The general consensus among motorcycle safety stakeholders suggests that helmets are

considered essential safety protective gear for motorcyclists; however, it is important to

understand how barrier type or design may influence the likelihood of an injury as it relates to

helmet use. Daniello and Gabler (2012) determined that injuries due to motorcycle-barrier

crashes commonly affect the upper and/or lower extremities. Bambach et al. (2012) further

determined that the motorcyclist’s thorax region experienced the highest incidence of maximum

injury in fatal motorcycle-barrier crashes. It is important to note that studies have shown wearing

a helmet does not guarantee a risk-free impact between motorcycle and barrier; however, some

personal protective gear may serve as a safety countermeasure (e.g., motorcyclist armored vest).

Research has shown that protective body armor can reduce injuries from motorcycle crashes, in

general (de Rome et al., 2011). Daniello and Gabler (2011) concluded that there is no statistical

difference regarding the odds of severe injury for helmeted or unhelmeted motorcyclists when a

collision occurs with a cable barrier or a guardrail. This observation seems logical given that the

majority of injuries due to crashes into this type of barrier appear to result in injuries to the

motorcyclists’ extremities.

Daniello and Gabler (2011) further determined that if a rider was helmeted, the odds of severe

injury in guardrail collisions were 1.419 times as great as the odds of severe injury in concrete

barrier collisions. In addition, the odds of severe injury for helmeted riders in collisions with

metal barriers were found to be significantly greater (at the 0.05 level) than the odds of severe

injury in concrete barrier collisions. Analyses of riders with and without helmets showed no

statistical difference at the 0.05 level in the odds of severe injury between collisions with a cable

barrier and collisions with a guardrail; however, their study only included a small number of

cable barrier collisions in the analysis when compared with the number of guardrail collisions.

CHAPTER CONCLUDING COMMENTS

Common roadside safety devices have historically targeted passenger cars and other motor

vehicles with four or more wheels. When a motorcycle comes into contact with one of these

roadside devices, the roadside barrier may not always function as a safety device. From a study

by Daniello and Gabler (2011), the researchers analyzed 951 motorcycle-barrier collisions

including guardrails, cable barriers, and concrete barriers. Of these devices, guardrail systems

had greater odds of resulting in severe injury for riders when compared to injuries associated

with crashes into concrete barriers. There is a need to understand better how the role of roadside

barriers may differ for motorcycle-barrier crashes when contrasted to crashes between other

vehicles and barriers. In addition, the rider position upon impact and the role of the motorcycle

helmet are two elements that should be considered with assessing how to optimize roadway

safety for motorcyclists while also balancing the safety needs of all users.

CHAPTER 2. ROADSIDE BARRIERS AND MOTORCYCLES

Chapter 1 identified some of the safety concerns associated with motorcycle crashes with

particular attention to injury level for crashes into roadside barriers. As documented in the

American Association of State Highway and Transportation Officials (AASHTO) Roadside

Design Guide (2011), transportation agencies in the U.S. typically deploy one of the following

three types of roadside safety barriers, examples of rigid barriers (typically concrete), semi-rigid

barriers (typically guardrail systems), and flexible barriers (typically cable or wire rope systems)

are shown in Figures 1-3, respectively.

©GGfGA

Figure 1. Example of a Concrete (rigid) Barrier.

©GGfGA

Figure 2. Example of a Guardrail with

Steel Posts.

©GGfGA

Figure 3. Example of Cable Barrier.

These barrier systems are intended to enhance safety by protecting/shielding vehicles from

conditions along the roadside which may be harmful to a driver if they leave the roadway, such

as traffic signs, bridge piers or steep drop-offs. Roadside safety barriers can be placed on the

outside of a roadway or in a median of a divided roadway. Some traffic signs can be designed so

they do not need to be protected by barriers (e.g., breakaway posts), but then the posts

themselves can still be struck. Roadside safety barriers are designed to contain and redirect

vehicles. In most cases the barriers only serve their intended purpose if they maintain the vehicle

(and therefore the occupants) on the impact side of the barrier. This is obviously a challenge in a

motorcycle impact at any kind of speed, as the rider can be separated from a motorcycle much

easier than a passenger can be ejected from a vehicle.

For a particular situation, the type of barrier used on a roadway is dependent upon the cost-

effectiveness of the barrier, the amount of space available and potentially the type of obstacle

being shielded (AASHTO, 2018). In the U.S., these barrier systems are tested and need to

comply with the Manual for Assessing Safety Hardware (MASH) standards (AASHTO, 2016)

prior to installation on the National Highway System (NHS) roadways. The U.S. MASH criteria

addresses a broad range of motor vehicles with different test levels and configurations including

testing a barrier system with passenger cars, pickup trucks, single unit trucks, tractor trailers, and

tractor tank trailers. However, MASH does not provide any guidelines or protocols to test

motorcycles against a barrier system. To date, there has not been a systematic approach

developed in the U.S. for similar testing protocols related to motorcycle safety.

Roadside safety barriers are recommended when it is determined that a barrier poses less of a

threat to a vehicle than the obstacle it is protecting. As noted, this consideration has been focused

on cars and trucks, not motorcycles. The different barrier types have different configurations and

therefore different concerns related to motorcycles.

CONTRASTING MOTORCYCLIST FATALITIES AND INJURIES BASED ON

BARRIER TYPES

It has been observed that motorcyclists are the leading source of fatalities associated with

guardrail crashes in the U.S. In 2005, motorcyclists suffered more fatalities (224) than were

experienced by passenger car occupants (171), or persons involved in any other type of single

vehicle crash involving guardrails (Gabler et al., 2007). NCHRP Project 22-26, Factors Related

to Serious Injury and Fatal Motorcycle Crashes with Traffic Barriers, specifically focused on

crashes involving roadside barriers. Although the final report is not yet public, it has been

presented that the study identified that motorcycle and barrier crashes remain an issue, as in 2017

motorcyclists accounted for 40 percent of guardrail related fatalities, while only 3 percent of

vehicles registered for use (Gabler et al., 2020).

Motorcyclists also have a high number of incapacitating injuries from crashes involving barriers.

This has been documented in a few studies using U.S. data. The proportion of single vehicle

motorcycle crashes that resulted in a fatality or incapacitating injury from an impact into a

roadside barrier was 32 percent in Washington State and 57 percent in Ohio (Gabaeur, 2014).

Similar studies using data from North Carolina, Texas, and New Jersey identified an average

value of 37 percent of the barrier related crashes resulted in a fatality or incapacitating injury

(Daniello & Gabler, 2011). Obviously, roadside barrier impacts by motorcycles have lethal

consequences, but there are also different types of roadside barriers. To look at the motorcycle-

barrier issue closer the type of barrier needs to be considered.

U.S. Studies Related to Barrier Type

Some limited studies have been conducted in the U.S. to specifically understand motorcycle

barrier crashes and barrier type. Daniello and Gabler (2011) conducted a study to determine

which type of barrier carries a higher risk for motorcyclists. The study consisted of an analysis of

motorcycle crashes into barriers for three states: North Carolina, Texas, and New Jersey. This

study used Google Earth to identify barrier type since this information was not available in the

police crash reports. Of the 951 motorcycle-barrier crashes they found 38 percent involved rigid

barriers (concrete), 57 percent involved semi-rigid barriers (guardrail), and 5 percent involved

flexible barriers (cable). They also assessed injury severity patterns in collisions with each

barrier type. They identified that 36.5 percent of the rigid barrier crashes were fatal, similarly 40

percent of the guardrail and cable crashes were also fatal. They found that crashes involving a

guardrail were 1.4 times as likely to result in severe injury (i.e., killed or incapacitated) as

compared to rigid barrier for helmeted riders. There was not a statistical difference for riders

without helmets. They also did not observe a statistical difference between guardrails and cable

barriers.

Guardrails themselves can come in different types. An ongoing study with the Texas Department

of Transportation (TxDOT) (Dobrovolny, 2021) found 689 of the total 68,838 reportable crashes

from 2010-2017 involved a motorcycle making contact with a guardrail as determined by the

Texas Crash Records Information System (CRIS) analysis. 94 percent of those crashes were

classified as Single Motor Vehicle (SMV). Of those 646 SMV motorcycle crashes involving a

guardrail, 109 resulted in a fatality and 215 resulted in an incapacitating injury. These serious

SMV motorcycle crashes involving guardrails occurred on 174 different roadways. To identify

the types of guardrails involved in the crashes, the research team viewed each crash site using

Google Earth. Two types of guardrail with different types of post, wood posts and steel posts,

were identified. Of those guardrails which were involved with fatal or incapacitating injury SMV

motorcycle crashes, 75 percent were constructed with wood posts. But, the steel posts had a

higher rate of fatal crashes compared to the guardrail with wooden posts.

European and other Non U.S. Studies Related to Barrier Type

This section examines research performed in Europe related to barrier type, realizing that barrier

types in these areas may be slightly different than in the U.S. The locations include Australia and

nearby New Zealand, Sweden, Germany, and England.

A study performed using data from motorcycle crashes with roadside objects in New Zealand

that specifically examined fatal crashes identified 77 percent that involved a guardrail, 10 percent

concrete barrier, and 8 percent a wire rope. The percentage of the different barrier types in New

Zealand was not specifically presented, but they did note that the barriers involved in the fatal

crashes were related to the volume of the type of barrier on the roadway, so the percentages

identified were in line with the exposure risks (Bambach et al., 2012b). Another study by the

same author using data from New South Wales, Australia from 2001 to 2009 found that 38

percent involved guardrails and posts while only 3 percent involved concrete barriers. As in the

case for New Zealand, the percent of the different barrier types in New South Wales was not

identified. They did conclude that based on the data concrete barrier collisions resulted in fewer

serious injuries as compared to guardrail (Bambach et al., 2013).

Sweden found that barrier crashes involving guardrail and wire rope barriers were similar when

comparing the severity of the crashes. Rizzi et al. (2012) analyzed police reported crashes of

motorcycles into road barriers between 2003 and 2010 in Sweden using the Fatal-Serious-Injury

Ratio (FSI) for different types of barriers. The FSI ratio is represented as the ratio of the number

of fatal and severely injured motorcyclists to the number of injured motorcyclists. The study

outcomes suggest that there was no statistically significant difference between FSI ratios for

guardrail type barriers and wire rope barriers, although these FSI ratios were generally high

(above 50 percent).

Outcomes of a crash statistics analysis conducted by Williams et al. (2008) indicated that in

England, there was a slightly increased serious injury or fatality risk to motorcyclists from

impacts with wire rope barriers (a 66.7 percent risk from wire rope compared to 58.3 percent for

all barriers). The risk was higher in Scotland with a 100 percent risk from wire rope and 58.3

percent from all barriers. However, there was less than a 1 percent impact per year between

motorcyclists and wire rope safety fences, so the data itself was limited.

Without the protection of a surrounding vehicle, motorcyclists have a higher likelihood of fatal

or serious injuries in a crash. Different barriers, barrier material types, locations on the road, and

even the rider’s position impacting roadside barriers are variables that further change the

likelihood of crash outcomes. The Federation of European Motorcyclist association (FEMA) has

reported that concrete barriers have some benefits over guardrails in that they have a larger

surface area to spread out any impact. They also note the concern of the safety of the cable

barriers by many motorcycle association’s in Europe. Due to the very thin nature of the cable

barriers, there is a perception that the impact on a motorcyclist is potentially worse than a

guardrail impact. FEMA noted anecdotal concerns with cable barrier impacts in their 2012

document “Standards for Road Restraint Systems for Motorcycles”. The FEMA document also

referenced the aforementioned studies by Williams in England and Scotland that found fatality

rates higher for wire rope barrier crashes as compared to other type barrier crashes (FEMA,

2012). It should be noted that the previously mentioned Rizzi study using data from Sweden and

the soon to be published NCHRP 22-26 project with data from the US both were not available

when the 2012 FEMA document was published. The newer studies (i.e., Sweden and U.S.) both

indicate that there is not a significant safety difference between guardrail and the cable/wire rope

barrier.

Both as related to the volume and severity, guardrail, and in particular guardrail posts, pose a

specific concern for motorcyclists in crashes. While recent crash data analysis indicates that there

is no significant safety difference between guardrail and cable barrier types, motorcyclists

generally have a higher concern with the cable barriers. This may be due to the fact that guardrail

is ubiquitous, while cable barriers are just starting to be installed in larger numbers.

Motorcycle Riders Injuries Related to Barrier Crashes

Daniello and Gabler (2012) offer an example of the types of injuries associated when a

motorcyclist strikes a barrier. The authors examined motorcycle crashes from 2006 to 2008 in

Maryland using the Crash Outcome Data Evaluation System (CODES) to better understand the

type, relative frequency, and severity of injures associated with this crash type. As a reference,

CODES data links police-reported crashes with hospital data to provide detailed information

about the injuries inflicted during a collision. Their results found four main crash modes for

motorcyclists that included single-vehicle barrier collisions, single-vehicle fixed-object

collisions, multivehicle collisions, and single-vehicle overturn-only. More than 70 percent of

motorcyclists involved in the analyzed crashes suffered an injury to the upper or lower

extremities, making this the most commonly injured body region for crashes. The authors also

found that motorcyclists involved in barrier collisions were 2.15 times more likely to suffer a

serious thorax (chest) injury than overturn-only collisions.

A study using motorcycle-barrier crash data from Sweden found the injury severity increased

when the rider separated from the motorcycle prior to the crash and slid as compared to the riders

that impacted the barrier upright (Rizzi, 2012). The authors also noted that previous crash tests

using anthropomorphic test devices (also known as test dummies) supported that, at similar

speeds, an upright barrier crash was more survivable than sliding into a barrier.

Research conducted by Bambach et al. (2014) investigated the crash mechanics and injury

causation of motorcyclist fatalities in Australia and New Zealand between 2001 and 2006. Only

crashes into a roadside safety barrier were used for the research project. Of the 20 fatal crashes,

half of the motorcyclists slid into the barriers and the other half impacted the barrier in an upright

crash posture, two types of position impacts that have been identified previously. Approximately

half of those impacting the barrier in an upright position slid along the top of the barrier. After

evaluating the crashes, the mean pre-crash speed and impact angle were determined to be

100km/h and 15 degrees respectively, and the thorax regions had the highest incidence of

maximum injury followed by the head region.

BARRIER TYPES AND MOTORCYCLES

Each of the barrier types have potential benefits as well as limitations that should be considered

when evaluating safety performance of motorcycles and their interaction with barriers. Rigid

(e.g., concrete) barriers are the most expensive to install but typically have the least long-term

maintenance. For concrete barriers, motorcycle riders are mainly observed to be ejected or

vaulted to the other side of the barrier. Semi-rigid systems, such as guardrails, are the most used

safety barrier systems in the US. Research shows that motorcycle crashes involving riders

include both sliding into the guardrail and crashing into it in an upright stance. For discrete

elements (e.g., sign posts), and what has been reported in cable barrier crashes so far, the

interaction of rider is primarily in the form of a head-on collision. This report separates cable

barrier and discrete posts into two categories due to the current perception in the motorcycle

community that cable barrier is not just a post impact concern.

The next section describes some of the issues particular to the different barrier types and

potential countermeasures that have been found in the research to address the concern. The

following categories and sub-categories related to crash impact will be described:

• Rigid Barriers (Concrete)

• Ejection over barrier

• Semi-Rigid (Guardrail)

• Sliding (discrete post impact)

• Upright (lacerations, tears or snagging with post top due to sliding on top rails)

• Flexible (Wire Cable)

• Unprotected Posts (discrete post impact)

Rigid Barriers

Rigid barriers are typically used in areas with limited lateral clearance as they are designed to

allow minimum deflection after impact with vehicles. ©Texas A&M Transportation Institute

Figure 4 depicts an example of a rigid concrete barrier. Concrete barriers are a type of rigid

barrier provided in the form of continuous sections joined to provide a smooth containing

surface.

Concrete barrier systems are often built to a height of 32 inches. Some systems might be as tall

as 54 inches. During impact of a motorcycle, however, the limited barrier height likely does not

contain the impacting upright motorcycle rider. Depending on the mode of impact, this could

result in the impacting rider being ejected from the motorcycle and landing on the opposite side

of the barrier. For concrete barriers in a median that could mean being thrown into on-coming

traffic. Concrete barriers can also usually be found around curves, on hills, and on bridges, etc.

which presents the problem if a motorcyclist is thrown over the barrier, the ejected rider would

be left potentially falling to his or her death after ejection from the motorcycle. These barriers

present other issues for motorcyclists such as redirection into traffic. This type of crash could

also lead to a fatal injury, especially if the rider loses control of the motorcycle and is redirected

into the travel lane of a high-volume roadway.

©Texas A&M Transportation Institute

Figure 4. Rigid Concrete Barrier.

Issue: Concrete barriers provide relatively less threat to motorcyclists considering there is a

smooth surface for the rider to slide after impact. However, the sliding rider impact and lack of

containment can still be a problem for such barriers.

Concerns associated with concrete barriers include:

• Impact into the rigid structure

• Crashes can result in the ejection of the upright motorcycle rider over the barrier possibly

resulting in striking the object the safety barrier was designed to protect against. Figure 5

shows a simulation of a motorcycle impact of a concrete barrier leading to the rider being

ejected over the barrier.

• Redirection of the motorcyclist back into the traffic stream.

Potential Countermeasure: Continuous protection on the top of the barrier can be provided to

prevent the rider ejection over the barrier. Such protection can help contain the rider after upright

motorcycle impact.

©Texas A&M Transportation Institute

A. Motorcyclist impacting a concrete

barrier

©Texas A&M Transportation Institute

B. Motorcyclist being ejected and

vaulting over a concrete barrier

©Texas A&M Transportation Institute

C. Motorcyclist being ejected over a

concrete barrier

Figure 5. Example of Simulated Motorcylist Impact With a

Concrete Barrier.

Research on this type of containment system is underway at the Texas A&M Transportation

Institute (Dobrovolny, 2021). Researchers are working with TxDOT engineers to develop

computer simulation plans that include proposed nominal impact conditions (e.g., speed and

angle), critical impact points, and Anthropomorphic Test Device (ATD) containment and

redirection. This is important since U.S. standards for motorcycle testing do not exist. A chain

link fence system was preferred over other options since it was more economical with good

availability, ease of installation, and ease of maintenance. Seven pendulum tests were performed

and determined a 2x2 chain link mesh size, and top and bottom steel horizontal rails with

discrete steel connections spaced at approximately 1 ft. The simulation used a 32 in high

concrete barrier installation that was rigidly installed and had a radius of curvature of 500ft. A

retrofit U-shaped post design minimized the likelihood of an errant upright motorcycle rider

directly impacting the discrete posts of the chain link fence system. The simulation showed no

interaction between the ATD and the retrofitted U-shaped post. The U-shaped off-set posts were

designed with the distance from the barriers similar to the distance a road sign would be if

attached to the concrete barrier. See Figure 6 and Figure 7 for the design.

©Texas A&M Trans-

portation Institute

Figure 6. Design of Retrofitted U-Shape Post with Barrier.

©Texas A&M Transportation Institute

Figure 7. Tested Retrofitted Design on the Test Site.

The photos presented in Figure 8 show a motorcycle test conducted at TTI’s testing facility.

Figure 8C, shows that the motorcyclist does not come in contact with the posts which was a

concern of which the engineers and reseachers were mindful. The retrofitted U-Shaped Post and

mesh fence containment system was considered suitable for implantation at locations where an

upright motorcycle rider containment option is need and/or desired. MASH TL-3 compliance

testing is still needed to evaluate the structural integrity of the system, occupant risk, and vehicle

deformation.

©Texas A&M Transportation Institute

A. Crash test picture of ATD with

motorcycle impacting chain fence

(front view).

©Texas A&M Transportation Institute

B. Crash test picture of ATD with

motorcycle impacting chain fence (side

view).

©Texas A&M Transportation Institute

C. Crash test picture of ATD with

motorcycle impacting chain fence

(perspective view).

©Texas A&M Transportation Institute

D. Crash test picture of ATD with

motorcycle after impacting chaining

fence (perspective view).

Figure 8. Sequential Images of Crash Test of a Motorcycle into a Fence.

Semi-Rigid Guardrail Systems

Semi-rigid barriers are designed to allow higher deflection of the system under impact loading

due to vehicles as compared to rigid barriers. The Midwest Guardrail System (MGS) as shown in

Figure 9 is a typical example of a semi-rigid barrier. Guardrail type roadside barriers are the

most common barrier type employed. A crash of a motorcycle into a semi-rigid barrier could be

expected to result in injuries including lacerations due to the motorcyclist sliding on top of the

rail or severe injuries due to the motorcyclist directly impacting a guardrail post. Therefore,

semi-rigid barrier motorcycle impacts are further classified as guardrail system post-beam

(sliding) and guardrail system post-beam (upright).

©Texas A&M Transportation Institute

Figure 9. Semi-Rigid Midwest Guardrail System.

Guardrails (Post-Beam Systems) – Sliding

Issue: The typical guardrail system used in the U.S. as a roadside safety barrier consists mainly

of two elements: the longitudinal rail which is continuous, and the discrete posts (with or without

a blockout) to support the rail. Guardrails have been designed and tested to redirect and contain

motorized vehicles such as cars and trucks; however, as indicated earlier it is not necessarily a

suitable option if the primary goal is to mitigate motorcyclist injuries.

A problem associated with existing guardrail options is that discrete posts serve as a fixed object

against which a sliding rider can impact, potentially resulting in a serious injury or fatality. A

depiction of a three-dimensional simulation/model of an ATD sliding into a discrete post can be

seen in Figure 10.

©Texas A&M Transportation Institute

A. Simulated ATD sliding into a

discrete post.

©Texas A&M Transportation Institute

B. Simulated ATD impacting a

discrete post.

©Texas A&M Transportation Institute

C. Simulated ATD redirected update

to top of discrete post after impacting

a discrete post.

Figure 10. Impact of Anthropomorphic Test Device into Discrete Post.

Potential Countermeasure: Options which provide bottom protection to the guardrail systems to

prevent or cushion rider interaction with discrete elements of the guardrail, such as posts, can be

adopted to enhance motorcycle safety (see Figure 11 as an example). The protection can be

related to the post themselves (non-continuous) or continuous along the bottom portion of the rail

such that it covers the posts and in between the posts. Continuous protection systems also can

contain a rider from going between posts, under the guardrail, and striking the object the

guardrail was installed to protect. Continuous systems are referred to as Motorcycle Protection

Systems (MPS) in this report (Europe also uses the term rub rail).

• Lower Rails: MPS or continuous rails made of different materials such as plastic or metal

are available to install as a bottom protecting option for the guardrail systems. See Figure

11 which shows the crash test simulation pictures of an ATD impacting a lower rail and

being redirected. As shown in the figure, adding lower rails allows a motorcyclist to slide

along the bottom rail, instead of impacting a discrete post, to help mitigate serious

motorcyclist injuries.

• Post Attenuators: Devices covering the discrete posts can be provided to mitigate injuries

due to sliding rider impacts. This is a non-continuous protection covering only the posts.

MPS systems address the sliding motorcyclist problem by redirection, containment, energy

dissipation, preventing head on collision with discrete posts, and minimizing rider interaction

with the posts. However, providing protection for only the lower portion of a guardrail would not

address the problems associated with upright position impacts and containment.

©Texas A&M Transportation Institute

A. Simulated ATD impacting bottom

rail protection.

©Texas A&M Transportation Institute

B. Simulated ATD redirected after

impacting bottom protection rail.

©Texas A&M Transportation Institute

C. Simulated ATD redirected away

from bottom rail after impacting.

Figure 11. Crash Test Simulation with Continuous MPS to

Address Sliding Motorcyclist Impact with Discrete Posts.

U.S. States Experience with Motorcycle Protection Systems (MPS)

Several state DOTs have recently installed MPS systems (produced as Barrier System’s DR-46

Motorcycle Barrier Attenuator). The results have not been formally documented in research

reports due to the recent time frame. The information shared here was from unpublished work

and personal correspondence.

California: The roadside safety research group in CalTrans have shared information about their

experience with installation of a MPS in California. They used a commercially available barrier

termed DR-46. After the installation in 2011-2012, the barrier did not experience any impacts

until May 2019. Researchers believe that the system served the function of preventing any

negative motorcyclist impacts on the roadside system. The yellow color of the barrier system is

also considered as a possible factor to attract rider attention and prevent crashes (Personal

communication between C. Dobrovolny and B. Meline [CalTrans], May 24, 2019).

North Carolina: Considering the results obtained by the MPS installed in California, NCDOT

also decided to install MPSs on critical roadway sections to control motorcyclist injuries and

fatalities. NCDOT had previously performed other motorcycle specific countermeasures along

NC 143, Cherohala Skyway, such as paving shoulders and improving curve warning signage, but

they were still experiencing motorcycle crashes. This roadway is known by the motorcycle

community as part of a motorcycle route known as the “Tail of the Dragon/Cherohala Skyway”.

In 2017, a review of five-year data on guardrail crashes identified 31 motorcycle crashes

involving roadside barriers (guardrail). Out of those 31 crashes, 2 resulted in a fatality and 11 in

an incapacitating injury. As a part of a safety project, NCDOT installed approximately 3,500 feet

of an MPS (also DR-46) on six hot-spot locations in this high incident corridor. However, due to

the recent installation (December 2018), it is difficult to determine the effectiveness of the MPS

in reducing crashes and injuries involving motorcycles. NCDOT received a very positive

response from the motorcycle community for undertaking this safety project. Further, they felt

that the maintenance and installation of the MPS was also fairly simple and quick. The

information included in this section was retrieved from an AFB20 committee presentation by Mr.

Bucky Galloway from the North Carolina Department of Transportation (see Galloway, 2020).

Utah: The Utah Department of Transportation (UDOT) has taken significant steps to mitigate

motorcyclists’ injuries due to discrete guardrail element impacts. UDOT installed commercially

available MPS (also DR-46) on a section of State Route 35. Crash data collected by UDOT

suggests an improvement after installment of the MPS. Although not analyzed statistically, the

data reveals that before installing the barrier during a 6-year period, motorcycle crashes resulted

in 12 injuries and 1 fatality. After installing the MPS, within a 3-year period, there has been only

1 reported motorcyclist injury. Since the DR-46 is not currently sold in the U.S., procurement of

the MPS was difficult and involved sole source issues. Also, the DR-46 required being removed

every winter so the snowplows would not damage it, as it is installed very close to the ground.

Utah DOT retrofitted another guardrail installation on SR 191 by using a standard W-beam rail

that was powder coated yellow, similar in color to the DR-46, and mounting it below the regular

guardrail, similar to where a DR-46 would be installed, but a little higher so it did not need to be

removed for snow plowing, as illustrated in Figure 12. Data collected by UDOT for this retrofit

showed good results. In the 5 year period before installation of the MPS, 5 motorcycle injuries

were reported within the roadway section. After installation, during a 3-year period, no injuries

were reported.

Figure 12. Illustration of Retrofitted Guardrail.

Similar to the powder coated rail retrofit, the UDOT also installed galvanized W-beam rub rail

on a guardrail system on SR 167, but this added rub rail was not powder coated yellow, it was

the same color as the original guardrail. Data showed that before installation, during an 8-year

period, motorcycle impacts resulted in 2 fatalities and 19 injuries. After installation of the MPS,

during a 2-year period, motorcycle crashes resulted in 2 fatalities and 8 injuries. No studies have

examined the effectiveness of this MPS design. This does emphasize that as more MPS are

installed, more in-depth analyses, like the types of crashes (i.e., sliding or vaulting over the top)

are needed to understand their potential benefits and limitations. The information in this section

was retrieved from a TRB AFB20 committee presentation by Mr. Debenham from UDOT (see

Debenham, 2020).

Non-U.S. Experience with Motorcycle Protection Systems (MPS)

France was an early adopter of testing retrofitted guardrails with a lower beam for the protection

of motorcyclists. They actually used ATDs in their MPS studies in 1979 and 1980. Germany also

has a long history of use, the Bundesanstalt für Strassenwesen (BASt) (the German equivalent of

FHWA) reported installing 80 kilometers of MPS in 1984 as part of an experimental effort

(Domhan, 1987). Impact tests performed for the BASt using the “Schweizer Kastenprofil” or

swiss box profile rub rail confirmed that the risk of injury to motorcyclists with the modified

guardrail system was lower than without the retrofit (Berg et al. 2005).

In 2012, FEMA identified the variety of testing protocols used in Europe for evaluation of MPS

(FEMA, 2012). FEMA identified that the French L.I.E.R. (Laboratoire d’essais INRETS

Equipment de la Route) test protocol was used in France and Portugal. The MPS evaluation

standard that is used in Spain is similar to the French version. The Spanish version is from

Asociación Española de Normalización y Certificación (AENOR) and is known as UNE 135900.

Italy and Germany both used a protocol from BASt. FEMA has recommended a more

coordinated effort for approval of MPS by adopting a common European standard (EN 1317-8).

Additional information on the existing European standards can be found in Chapter 3. Note that

EN 1317-8 was recently (2019) changed to CEN/TS 17342:2019 – European Standard for

Motorcycle road restraint systems.

It has been reported that Norway has developed guidance for the locations of MPS, and that

Spain, Portugal, Germany, Australia and New Zealand are also pursuing retrofitting of guardrails

with MPS (Nordqvist, 2016).

South Australia performed a case study of two different motorcycle protection systems (flexible

fabric and steel mesh) in a popular location for motorcyclists, especially for weekend travel in

the mountainous Adelaide Hills area. The specific installations were on Gorge Road and Cudlee

Creek Road. Historically (2001-2010 data) over 40 percent of the casualty (i.e., injury and fatal)

crashes on these two roads were due to motorcycles, and 34 percent of those motorcycle crashes

involved impacting the guardrail (termed guard fence in Australia). After MPS installation, no

serious or fatal injury crashes were recorded on either road that involved a guardrail. There were,

however, 20 motorcycle crashes with 2 of the crashes reported to have involved the guardrail.

One of the guardrail crashes was Property Damage Only (PDO) and the other involved a minor

injury. Although not enough time had passed to evaluate the installations for a true before/after

comparison, there was evidence that indicated the single crash resulting in PDO could have

otherwise resulted in much worse injury without the MPS. In addition, there was not enough data

to compare the fabric and steel MPS systems, but vandalism was noted as a significant concern

for the fabric MPS, as it was slashed in several places shortly after installation (Anderson et al.,

2012). Figure 13 and 14 show two different views of the fabric MPS.

©Federal Highway Administration

Figure 13. Back View of Fabric MPS.

©Federal Highway Administration

Figure 14. Front View of Fabric MPS.

TRL of the Transport Research Foundation identified a number of proprietary motorcycle

protection systems in use (Williams 2008). Some of the systems were designed to be retrofitted

on existing guardrails (e.g., BikeGuard, DR46, Ercawn Motard, MotorRail, MOTO-SHIELD,

Mototub, SP4) and others were guardrail systems specifically made for motorcyclist protection

(e.g., CUSTOM [Containment Urban System for Motorcyclists]).

The Center for Road Safety in Austrlia has documented the results of MPS crash tested for both

motorcycle and vehicle impacts. Three different types of MPS were added to a standard W-beam

guardrail. Each of the MPS systems were tested, along with the standard W-beam guardrail

without the MPS as a comparison. Testing was performed in accordance with the European test

standard for motorcycle testing EN 1317-8 (described in more detail in Chapter 3). The

passenger car test was based on NCHRP 350 Test 3-11(2000 kg pickup truck, 100 km/h at an

angle of 25 degrees) but it used a 1600 kg sedan instead of a 2000 kg pickup truck. The standard

W-beam guardrail did not meet the motorcycle safety criteria (EN1317-8) but passed the

passenger car safety criteria (NCHRP 350 modified). All three of the MPS passed the

performance criteria used for passenger car safety, but only two of the three MPS met the

motorcycle safety criteria (Baker et al. 2017). This indicates that MPS can be installed without

causing undue harm to passenger vehicles.

MPS can also attempt to specifically address head on collision related injuries with discrete

elements such as the posts of the guardrails while sliding into it. TRL also described products

designed to cover discrete posts that are designed using foam type material to absorb forces on

an object (e.g., helmet or head) as it collides with a post (Williams 2008).

Guardrails (Post-Beam Systems) – Upright

Issue: Similar to guardrails described for the sliding motorcyclist problem, W-beam guardrail

systems also pose a risk for a rider impacting it in an upright configuration (Figure 15 depicts

two W-beam guardrail system concerns for upright riders). Issues associated with existing

guardrail options when a rider is impacting the rail in an upright position include:

• Longitudinal rails can result in severe head injuries and lacerations for the rider, while

impacting in an upright position, the rider can slide along the top of the guardrail

impacting several posts before finally resting on either side of the system.

• Severe injuries can occur after rider impact with the guardrail system due to ejection on

the other side of the system.

©Texas A&M Transportation Institute

A. Simulated ATD striking and then

vaulting over a W rail.

©Texas A&M Transportation Institute

B. Simulated ATD striking a W rail and

then impacting their head on the discrete

post.

Figure 15. Motorcyclist Impacting the Rail and Discrete Posts of

a Guardrail System.

Potential Countermeasure: Continuous or non-continuous options which provide top protection

to the guardrail systems to prevent rider interaction with longitudinal rail edges, and discrete

elements of the guardrail, such as top of the posts, can be adopted to motorcyclists’ impact with

guardrails. The MPS noted earlier do not provide protection to riders from guardrail elements

such as the top of the posts. Similar to bottom protection plates, a continuous bent plate can be

provided on the top covering the posts which allows the rider to slide without severe injuries.

Figure 16 shows a guardrail top with protected longitudinal rails. The crash test is a part of an

ongoing TxDOT project aiming to retrofit guardrail systems for motorcycle safety (Dobrovolny,

2019).

Top Rail: Has a smooth vertex on top that will help provide flexibility and dissipation of energy

during impact with the rider.

Bottom Rail: Uses the opportunity for dissipation of energy of impact by accommodating small

deformations and rotation during impact event. This also minimizes the distance between the flat

bottom rail and the existing MGS rail.

Figure 16 shows a crash test of an ATD at TTI’s testing facility. An important question that

needed to be addressed before the crash test was conducted was the criteria for the Upright

Motorcycle Test. There were 2 performance indicators to be considered: the severity levels (that

focus on head injury criteria (HIC) and neck forces) and ejection during the test since the ATD is

not allowed to remain trapped or suffer any detachments of limbs.

Recommended Testing: The following tests were recommended to address the priority need of

the study:

1. MASH test 3-10 (passenger car)

2. MASH test 3-11 (pickup truck)

3. Upright motorcycle test with seated ATD rider

4. Sliding ATD test aiming at mid-span between posts

5. Sliding ATD test aimed at discreet post

©Texas A&M Transportation Institute

A. Side view of an ATD sliding on

top of an MPS during a Texas A&M

Transportation Institute crash test.

©Texas A&M Transportation Institute

B. Perspective view of an ATD

sliding on top of an MPS during a

Texas A&M Transportation Institute

crash test.

Figure 16. ATD Sliding Along the Top of a TxDOT MPS in a

Texas A&M Transportation Institute Crash Test (Dobrovolny

et al., 2019).

Flexible Cable Barriers

Flexible barriers (see Figure 17 as an example) are designed to allow even higher deflection than

semi-rigid barriers. Consequently, a flexible barrier allows energy dissipation mainly through

deflection of the system. Cable barriers and weak post W beam guardrail systems are examples

of flexible barriers. While weak post guardrail poses the concern of impacting the rails as noted

previously, cable barriers also pose a concern for impacting the thin cables. Decapitations and

amputations have been reported in the literature related to extreme speeds and cable barriers in

Australia and New Zealand, but the same study also identified decapitations and amputations

based on guardrail impacts (Bambach et al., 2010).

Signposts have similarities to posts used in flexible barrier systems. A motorcycle crash into a

flexible barrier or a signpost can result in severe injuries due to the motorcyclist directly

impacting a post. Cable barriers typically have smaller posts that are spaced farther apart than

guardrail, which would respectively lessen the severity and chance of impact with a cable barrier

post as compared to guardrails.

©Texas A&M Transportation Institute

Figure 17. Flexible Barrier – Cable Rope Barrier.

Issue: Cable barriers are provided with continuous rope-wire elements acting as a beam to

contain motor vehicles. However, these rope-wires are perceived to induce a “cheese-cutter”

effect on motorcyclists when impacting such barriers. The contact area with a motorcyclist

would be concentrated in the small wire diameters upon impact. Although the wire-rope barriers

are provided with continuous cables, they have a large portion of the posts exposed to the

motorcyclist in case of an impact event. This can again result in discrete post impact resulting in

fatalities.

Potential Countermeasure: Although the cable barriers are widely perceived as potentially

harmful for motorcyclists, the data suggests that they have provided great benefits to reduce

highly fatal cross over motor vehicle crash fatalities in both the U.S. and Europe (Grzebieta el

al., 2009). The discrete posts can be provided with post caps to mitigate head injuries. However,

this would not address the redirection and containment issue pertaining to sliding and upright

motorcyclists and does not address the “cheese-slicer” perception. Since cable barriers are

relatively new, and such a low but growing proportion of the overall volume of roadside barriers,

additional research is potentially needed specifically related to cable barriers and motorcycle

crashes. It is anticipated that the NCHRP 22-26 report will provide additional data on this topic,

specifically as related to current conditions related to barriers in the U.S.

Motorbike writer.com (see Hinchliffe, 2012) recently shared that an Australian motorcycle and

safety enthusiast is supporting what is being called the “Nelson comb”. They note that “The

device, made by Indian company TDCO Design, uses recycled plastic to form a hair “comb” that

is inserted into the wire barrier with a bottom rail snapped into the bottom gap” (Hinchliffe,

2012). While the article also noted that there was an issue with safety due to the cable in cable

barriers, they do not cite any references supporting the assertions. A depiction of the Nelson

comb device can be found in Figure 18.

Figure 18. Depiction of the 'Nelson Comb'.

Signposts

Signposts that are not protected like shown in Figure 19, are required to be breakaway to prevent

injury. Similar to barrier crash testing, breakaway testing only involves cars and vehicles.

©Texas A&M Transportation Institute

Figure 19. Discrete Sign Post System.

Issue: Signposts essentially act as a discrete post element on the roadside. Hence, the problem is

similar to sliding or upright riders impacting discrete posts. This can again lead to a fatal injury

to a rider due to head on collision with the post.

Potential Countermeasure: Discrete protection similar to the discrete post elements noted

previously could mitigate rider impact severity with the post. This would act like a post

attenuator to absorb the head-on collision impact. However, it is noted that post attenuators will

not address the redirection and containment issue pertaining to a sliding motorcyclist. It should

also be noted that due to the vast amount of sign posts this would definitely be cost prohibitive.

IN-SERVICE PERFORMANCE EVALUATIONS (ISPE)

It is noted that even though several countries outside the U.S. have implemented the use of

barriers on roadway sections, no studies or reports are available which illustrate in-service

performance evaluations (ISPE) of those systems. Conducting an ISPE of existing motorcycle-

friendly barriers is an important topic to address to understand if these systems serve their

intended purpose. Not only would an ISPE indicate the adequacy of such barriers to motorcyclist

impacts, but it would also provide an indication of whether they still meet current standards for

vehicular impacts.

The objectives and need of developing ISPEs have been stated is the AASHTO Manual for

Assessing Safety System (AASHTO, 2016), which is the latest U.S. standard for testing and

evaluation of roadside safety hardware. This document highlights the importance of ISPEs by

stating that “ISPE allows user agencies to identify overall impact performance of a feature as

well as identify potential weakness or problems with the design” (AASHTO, 2016). It also states

that ISPE will “demonstrate that design goals are achieved in the field and identify modifications

that might improve performance” (AASHTO, 2016). Although the document refers to ISPEs

specifically for vehicular impacts, the objectives and needs would remain for motorcycle

impacts. Further, it is important to conduct ISPEs to ensure field performance of roadside safety

devices which might be affected due to differences in crash testing and actual crashes such as

field impact conditions, site conditions, configurations, etc. (AASHTO, 2016).

COST AND IMPLEMENTATION

Two primary considerations for many stakeholders are the costs to install and maintain

“motorcycle friendly” barriers and their relative ease of implementation. Barriers that are costly

and/or are difficult to implement will either be adopted very slowly or not adopted at all, thus

limiting or even negating any potential advantages that the barriers may offer to motorcyclists.

A central finding from the work conducted here is that due to the new and somewhat novel

nature of these barrier systems, there is little information readily available that can describe fully

the range of installation and maintenance costs and ease of implementation. In the absence of

conducting a large-scale survey of manufacturers and practitioners in the U.S. and abroad (e.g.,

Europe, Australia) the current work summarizes an example from the U.S. where information

has been made available.

NCDOT installed the Lindsay Transportation Solutions’ DR-46 Motorcycle Barrier Attenuator

(MBA) in Graham County, NC in several curves along NC-143. The DR-46 MBA is a

polyurethane barrier system that can be added with metal zip ties to an existing guardrail with on

roadway curves that exhibited a documented pattern of guardrail crashes. It is also manufactured

in yellow to provide a visual warning for motorcyclists. NCDOT indicated they were impressed

with this barrier system (Galloway, 2020)

The cost of the DR-46 MBA was $30/lf, including delivery and NCDOT viewed the installation

experience as extremely easy (Galloway, 2020). While NCDOT used a qualified guardrail

installer for this project, it was noted that installers do not necessarily need to have a guardrail

installation background to install this barrier system and that the NCDOT felt comfortable with

their maintenance staff installing or replacing segments of the barrier system (personal

communication with Mr. Bucky Galloway). As part of the project, NCDOT purchased additional

DR-46 rail sections to be used when needed for replacement of damaged sections (Galloway,

2020).

A limitation noted by NCDOT was that if the height of the existing guardrail system was

significantly lower than the NCHRP Report 350 height standard of 27 inches, the DR-46 would

not fit between the bottom rail of the W-beam guardrail and the ground. This was one of several

reasons why NCDOT made the decision to upgrade all the guardrails in the installation area

where the DR-46 was installed (Galloway, 2020). Another option explored by NCDOT was to

cut the shoulders around the guardrail to allow for sufficient space but they felt more

comfortable upgrading the guardrail to MASH standards (personal communication with Mr.

Bucky Galloway).

NCDOT did identify one challenge regarding the purchase of the motorcycle retrofit system.

Specifically, because the purchase was a sole source procurement and the product was being

purchased from Italy, the overseas shipping added costs and delays, and the sole source

procurement created some issues that delayed the process by a few months (personal

communication with Mr. Bucky Galloway). Utah addressed the sole source issue and cost of the

DR-46 in their later installations by using a typical piece of W-beam guardrail, and installing it

underneath the existing guardrail as shown in Figure 12. At the time (pre-MASH) it was

considered a rub rail and did not need to be crash tested for passenger vehicles. If a retrofitted

system like this was tested both for MASH and motorcycle safety it may be a potentially cost-

effective measure to address motorcycle hot spots.

NCDOT noted maintenance issues that may be of interest for many U.S. States. NCDOT does

not remove the barrier during the winter and, to date, has experienced minimal damage to the

barrier from snow clearing operations. One of the main reasons NCDOT decided to leave the

barrier in place during the winter is the fact that NC 143 does see a relatively high volume of

motorcycle traffic on warm, dry weekends during winter months. An addendum to their

comments indicated that while the section of NC 143 where the DR-46 is installed does receive

above average snowfall for Western North Carolina, the amount does not compare to the large

amounts of snow received by other parts of the U.S., such as the northern and Midwestern States,

where more frequent snow removal may increase the amount of damage to the DR-46. Chapter 2

discussed the potential value of highlighting the lower guardrail with a contrasting color (yellow)

to further influence motorcycle crash rates. To receive the full linear delineation benefit out of

the yellow DR-46 rail, NCDOT found that there was a need to increase the number times that the

area was mowed each season to reduce vegetation height.

As indicated in Chapter 2, the NCDOT saw an overall reduction in the severity of motorcycle

crashes as well as an overall reduction in the frequency of motorcycle crashes along the portions

of NC 143 where the DR-46 was installed. In addition, the motorcycle community expressed

positive comments with this project and has been very vocal about their support for this and

other projects that improve motorcycle safety.

CHAPTER CONCLUDING COMMENTS

Roadside barriers are necessary elements that are intended to protect a motorist that leaves the

roadway from encountering an even more significant obstacle. But, since motorcycles are such a

small minority of motorists on a typical roadway, barriers have traditionally been designed and

built in the U.S. with the consideration of cars and trucks, not motorcycles.

This section has provided information on the different types of roadside barriers and how

motorcycle impacts with these barriers differ. Potential countermeasures, such as motorcycle

protection systems (MPS) for guardrails, have been identified as related to the type of impact as

related to the barrier. Some promising installations of MPS have also been shared, while their

time in service has been limited to date.

CHAPTER 3. NEXT STEPS AND POSSIBLE FUTURE ACTIVITES

A significant component associated with many motorcyclist crashes is the interaction between a

motorcycle and an infrastructure-based element such as the roadway surface, lane striping, and

signs and posts as examples. It is easy to envision a situation in which the risk of a motorcycle

crash increases significantly due to pavement that is worn over long-term use and offers reduced

traction. While it is easy to identify elements such as worn pavement as potentially contributing

to motorcycle crashes, it is more challenging to appreciate those infrastructure-based

countermeasures that are specifically designed to improve safety as potential contributors to

reduced safety, particularly for motorcyclists.

This report focused on synthesizing research and engineering practices relative to roadside

barrier design. As indicated in prior chapters of this report, barriers can have positive safety

influence in a motor vehicles/barrier crash but can present significant safety issues for

motorcyclists being lacerated when sliding across the top of a barrier, receiving significant

thoracic injuries when impacting concrete barriers, colliding with the posts that support barriers,

and vaulting over a barrier. The potential for barriers to reduce safety for motorcyclists is not

insignificant and presents an engineering challenge to redesign barriers to improve the safety of

motorcyclists but also retain the existing safety advantage for motor vehicles.

In response to this safety critical situation, the engineering and research community has

developed or is in the process of developing “motorcycle friendly” barriers that are intended to

minimize or eliminate motorcyclists’ fatalities and serious injuries when impacting a barrier (see

Chapter 2 of this report). While the new designs offer great promise, they represent an initial step

in the longer quest for barriers to improve motorcyclist safety. Critical next steps include

identifying what barrier related topics have been developed as problem statements and submitted

for research funding and to identify potential barrier related research topics that could be

developed into problem statements and submitted for future funding. Conducting research on the

additional barrier-related topics would significantly advance not only how the field of

motorcycle barrier design is approached but also, ultimately, the ability of the barriers to reduce

the number of motorcyclists’ lives lost.

CURRENT PROBLEM STATEMENTS

Research relative to design and effectiveness is critical for continually improving motorcyclist

safety relative to barrier-motorcycle collisions. To gain a better understanding of what research

should be funded as part of future projects, it is first important to examine what research has

been conducted (see Chapters 1 and 2 in this report) and to then identify those research topics

that have been proposed. In the course of the current project, one problem statement submitted to

a federally funded program was identified along with a project that recently concluded but the

results were not yet released.

Development of Guidance for Enhanced Delineation of Barriers and other Roadside Safety

Hardware, Slopes, and Obstacles to Improve Visibility for Motorcycles.

Transportation agencies have encountered situations where enhanced continuous delineation of

the face of existing roadside barriers appears to reduce crash and injury severity. At the recent

AKD20 Roadside Safety Conference (Debenham, 2020), the Utah DOT noted that their

installations of a yellow powder coated metal motorcycle rub-rail under a standard W-beam

guardrail on two state-maintained routes resulted in a significant reduction in motorcycle crashes

and injuries. California Department of Transportation (CalTrans) installed the yellow colored

DR-46 motorcycle attenuator rub-rail in a curve exhibiting a high number of motorcycle crashes

and their evaluation, the number of motorcycle crashes in that curve reduced to zero. Similarly,

yellow DR-46 rails installed by the North Carolina DOT showed promise in reducing motorcycle

crashes, although the results are preliminary.

Based on preliminary before and after crash studies there appears to be an association between

enhanced longitudinal delineation and crash and injury reductions; however, although this

finding is encouraging, it is based on studies with limited experimental controls (e.g., multiple

treatment locations, multiple control locations). Research and development in this area should

examine the utility of enhanced continuous delineation as a first step but also develop guidance

to assist state and local transportation agencies in determining enhanced practice solutions for

delineating roadside safety barriers (and steep slopes). The guidance should be further

implemented through an update of appropriate sections of the AASHTO RDG, Manual on

Uniform Traffic Control Devices, and MASH.

The problem statement entitled “Development of Guidance for Enhanced Delineation of Barriers

and other Roadside Safety Hardware, Slopes, and Hazards” was submitted to the American

Association of State Highway and Transportation Officials Special Committee on Research and

Innovation for the NCHRP fiscal year 2022 program.

Factors Contributing to Injurious and Fatal Motorcycle Crashes with Traffic Barriers

As indicated in prior sections of this report, relatively little research has been conducted on fatal

and serious motorcycle collisions with barriers with some of this work being constrained by

significant research limitations. To address this need, the project entitled “Factors Related to

Serious Injury and Fatal Motorcycle Crashes with Traffic Barriers” was funded through an

NCHRP project (NCHRP 22-26) and conducted by the Virginia Polytechnic Institute and State

University and was completed in November, 2020. The project is listed in this report as a

problem statement because the final report was pending at the time of this report and has not yet

been released.

The objective of the research project was to identify the range of factors contributing to

motorcycle collisions with traffic barriers that resulted serious injuries and fatalities. The

research examined impacts with a variety of barriers such as bridge rails, cable barriers, concrete

barriers, crash cushions, and end terminals to understand better the association between barrier

type and injurious and fatal crashes.

POTENTIAL RESEARCH TOPICS

The prior research projects, current projects, and existing problem statements summarized in this

report support the notion that some tentative steps have been taken to address the potential

benefit that redesigned barriers could offer for improving motorcyclist safety; however, the lack

of an extensive list of projects and problem statements also suggests the need for additional

research. The following potential research topics were identified through a gap analysis based on

the results of the review of literature (summarized in Chapters 1 and 2 of this report) of

motorcyclist injuries and fatalities sustained in barrier related crashes and through discussions

with practitioners (e.g., state engineers). The gap analysis indicated there is an opportunity to

address several important research topics through future funding, each of which are summarized

below.

Development of a Motorcycle Testing Standard Addressing Motorcycle Testing and Impact

Configurations in the U.S.

Research conducted by Grzebieta et al. (2013) reviewed the European Standard EN 1317-8

(European Committee for Standardization, 2012) with regard to Australian motorcyclist

fatalities. The research identified the primary crash modes of sliding upright and ejection from a

motorcycle and concluded that both an upright and sliding position of a motorcyclists while

impacting a barrier were equally represented in the Australian-New Zealand crash data analysis.

However, EN 1317-8 does not provide any specifications or criteria for specify thorax injuries

(but it does contain a head injury criterion for sliding mechanisms). As indicated in Chapter 1,

thorax injuries represent a significant motorcyclist injury type.

It is clear that there are several potential research topics associated with this area. First, research

is needed to develop criteria for thorax injuries and an additional test using an ATD consisting of

colliding with a barrier in an upright position. Second, relative to testing standards, it is noted

that International standards (e.g., EN1317-8) do not contain test specifications and criteria for

upright position (they do however address a sliding motorcyclist test design) thus necessitating

research to examine this critical and common crash configuration. Lastly, there are no guidelines

addressing proper testing and use of motorcycle retrofit barriers in the U.S. Research is needed to

identify and validate appropriate standards for the U.S.

Research Examining In-Service Performance Evaluation

It is important to recognize that there may be differences in barrier performance between test and

actual site installation locations due to varying impact conditions at the barrier installation site,

differences in test and actual site conditions, and differences due to varying attention to

installation details. Due to these differences, it is important to monitor actual installation to

evaluate barrier performance and conduct evaluations of barriers that are currently in service.

These evaluations are typically referred to as in-service performance evaluations (ISPE).

As per AASHTO’S Manual for Assessing Safety Hardware (MASH), Second Edition

(AASHTO, 2016), the following are some of the objectives of an ISPE:

• To prove that the required design goals are obtained and to identify factors that could

improve system performance,

• To obtain a wide range of information on collision-performance characteristics of barriers

to determine failure/success ratios and associated damage repair costs,

• To determine factors that prevent a barrier from performing as anticipated,

• To determine the effect of climatic and associated environmental conditions on barrier

performance,

• To identify the features of barrier systems that impact highway conditions and operations,

and

• To obtain timely maintenance information about the system, damages, operations, etc.

Most importantly, ISPEs can help determine if installed barriers are serving the function for

which they were intended which, relative to the current work, would include reducing the rate of

motorcyclist serious injuries and fatalities due to motorcyclist-barrier collisions.

ISPEs can be performed by analyzing currently available crash data. Available data can be used

to analyze pre-installation crashes for motorized (including motorcycles) and non-motorized

vehicles (i.e., bicycles). The obtained data can then be employed to determine placement

guidance and MPS system design addressing vehicular issues. Data after installation can be

analyzed to indicate the degree of benefits or loss due to barrier installation. The conduct of such

studies can contribute significantly to an overall data analytic approach and would facilitate

system design and placement guidance.

A positive finding from the gap analysis is that some DOTs have started ISPEs of recently

installed MPS to enhance motorcyclist safety. In addition, MASH has included a section for

ISPE. However, given the overall lack of IPSEs conducted to date, there is a need to fund IPSE

studies to understand fully the potential benefits of barriers for motorcycles but also all

motorized vehicles.

Identification of Critical Locations to Implement Barrier Systems

State and Federal DOT resources and the potential benefits of barrier systems can be maximized

by understanding and identifying appropriate locations deployment. For example, installing

guardrail protection or barrier systems can be costly if installed across large areas so it may be

important to focus on those areas that truly require a safety countermeasure. In addition, roadside

barrier systems installed on curves can have different requirements than installations on straight

roads and they may differ based on roadway characteristics, such as rural roads versus urban

roads.

An ongoing study conducted by Dobrovolny and Goel (2021) for TxDOT involved investigating

placement guidance based on crash severity models that included factors such as the roadway,

roadside, operational, and environmental associated with severe motorcycle crashes involving

fixed objects in Texas. Their research showed that roadside elements have a significant impact

on crash severity. Using random forest and decision trees after conducting a regression analysis,

a framework for identifying high-risk locations for motorcycle crashes was developed. The

results of data mining were then used to identify potential sites for installing the MPS systems

for enhancing motorcyclist safety. Critically, this work underscores the ability to focus

installations and mitigation efforts on those sites most in need.

However, while the work conducted for the TxDOT is a promising start, there is a need to

expand these efforts to a wider range of location characteristics, barrier types and treatments, and

to different States that experience different geographical characteristics. With the development of

new MPS for barriers, it is also important to develop placement guidance for installation at

locations which are critical to motorcyclist safety.

Enhance the HSIS Database with information on Motorcycle Protection System Barriers

and additional Motorcycle Crash Data

Installation of MPS in the U.S is a relatively recent practice performed by State DOTs. As a

result, the availability of before and after MPS installation motorcycle-barrier crash data is scarce

and challenges the ability to make sound decisions regarding barrier installation and retrofit.

Motorcycle-barrier specific data itself is also very limited in the U.S., with the MCCS data only

containing 351 crashes. The current MCCS data format also does not now clearly identify cable

type barrier systems. Data on specific types of barrier are currently very difficult to compile, as

evidenced by the number of research reports that noted they used Google-Earth to identify

barrier type for each crash.

A more robust database of motorcycle-barrier crash related information would be a significant

resource to address MPS placement guidance and ISPE. Moreover, a database would facilitate

maximizing barrier effectiveness by addressing issues specific to certain regions or class of

vehicles. It is anticipated that the results of the NCHRP 22-26 research project will provide some

additional motorcycle crash data information. The Highway Safety Information System (HSIS)

that currently houses the MCCS data is a potential home for this and other motorcycle specific

data. There is a need to review the HSIS for future compatibility and potentially add some

elements to the MCCS to specifically address cable barrier, which is seeing increased use in the

U.S. The specific objectives of this work would include:

• Review the HSIS crash database to identify if it could act as a resource for various

applications such as barrier design, crash data analysis, barrier placement guidance,

performance evaluation, etc.

• Identify the feasibility of acquiring barrier specific information from other datasets

(potentially from their asset management systems).

• Developing a guideline for implementation of motorcycle friendly barriers in the U.S by

identifying best practices followed in the U.S or other countries.

• Understanding the barrier system implementation guidelines followed by states or

countries who have experience with installing MPS on roads.

• Investigating if the practices followed by such countries or states address the needs of

motorcycle safety.

TESTING STANDARDS AND PROTOCOLS

As stated earlier in this chapter, there are no U.S. based standards or protocols available to test a

motorcycle or motorcyclist impact with a barrier system, regardless of whether they are designed

for motor vehicles or designed/adapted for motorcycles. It will be helpful to examine existing

standards and protocols for testing and evaluation of motorcyclists impacting barriers in Europe

and elsewhere that may be considered as the basis for U.S. standards and protocols. It is noted

that these standards primary exist in Europe (e.g., EN 1317-8) but they are not complete as

evidenced by the lack of standards or protocols to test an upright motorcycle impact

configuration (testing standards are available for evaluating barriers for sliding test

configurations).

Existing Standards and Protocols

The existing standards and protocols include:

• L.I.E.R Protocol: Motorcyclist Safety Evaluation Regarding Barriers

• UNE 135900 Spanish Standard Protocol

• EN 1317-8 Road Restraint Systems

• ISO 13232 Test and Analysis Procedures for Research Evaluation of Rider Crash

Protection Devices Fitted to Motorcycles

• FEMA Motorcyclists and Crash Barriers Project

• AS/NZS 3845 Australian/New Zealand Standard

L.I.E.R. Protocol (1998): Motorcyclist Safety Evaluation Regarding Safety Barriers.

The crash test agency was the Laboratoire d’essais INRETS Equipment de la Route Laboratory

(L.I.E.R.), France. The L.I.E.R protocol consists of two tests with an ATD impacting a system in

two configurations that include an ATD aligned with the path of travel and aimed offset from a

post and an ATD aligned with the path of travel but parallel to the posts (see L.I.E.R., 1998).

These tests are conducted with the ATD sliding across the ground surface. The test conditions

are summarized below:

• Impact Speed: 60 km/h - 37.3 mi/h

• Impact Angle: 30°

• ATD: Standard ATD Model, with standard helmet and standard motorcyclist clothing

• Approval Criteria:

o The occupant risk should be investigated through instruments included in the

ATD. The resultant value for forces and moments should be within approved

biomechanical limits. (L.I.E.R., 1998)

o During the impact event, the impacting ATD shall not penetrate the impacted

system, nor should remained trapped in the system. (L.I.E.R., 1998)

UNE – 135900 Spanish Standard Protocol

The crash test agency was the Spanish Ministry of Public Works. This test protocol is similar to

the L.I.E.R protocol with some additional elements. In fact, the UNE protocol includes an

additional test speed of 70 km/h that was added in revised UNE – 135900 (2008) as compared to

60 km/h in the L.I.E.R specification (AENOR, 2008). In this protocol, the discrete element

protection systems (discontinuous systems) are also considered and a post-centered test and a

head-first test with an impact offset with regard to a post. A second impact is conducted between

two posts as compared to the L.I.E.R. protocol where it was conducted opposite to a post (rigid

element). This protocol also provides an additional biomechanical acceptance criteria along with

two different performance classes. The test conditions are summarized below:

• Impact Speed: 60 km/h - 37.3 mi/h; and 70 km/h (43.5 mi/h)

• Impact Angle: 30°

• ATD: Hybrid III 50

percentile male, with standard helmet and standard motorcyclist

clothing

• Approval Criteria:

o The evaluated barrier system should not yield to debris with a weight of more

than 2 Kgs. (AENOR, 2008)

o Degree of dynamic deflection and width of the system should not be more than

the limits for impact of 4- wheel vehicles specified by UNE EN 1317-2.

(AENOR, 2008)

o ATD should have no noticeable intrusions with no breakage of bones (with an

exception to clavicle). (AENOR, 2008)

o ATD should not reveal any damage or tearing of the clothing used for ATD.

(AENOR, 2008)

EN1317-8 Road Restraint Systems - Part 8: Motorcycle Road Restraint Systems which Reduce

the Impact Severity of Motorcyclist Collisions with Safety Barriers, Technical Specification

The crash test agency is the Comité Européen de Normalisation (CEN) Technical Committee on

Road Equipment (TC226). This specification (European Committee for Standardization, 2012)

was an addition to the EN 1317 standard for testing MPS. It specifically considered the sliding

motorcyclist position during impact for testing of the protection system. This standard is not

mandatory throughout Europe due to lack of experience of some countries with this test

specification. Hence, it was decided to accept the standard as a technical specification, thus each

country is free to install a barrier which is considered to provide safety with/without compliance

with this specification. The test conditions are summarized below:

• Impact Speed: 60 km/h - 37.3 mi/h; and 70 km/h (43.5 mi/h)

• Impact Angle: 30°

• ATD: Modified Hybrid III 50

percentile male, Motorcycle Helmet (polycarbonate shell)

satisfying Regulation 22 of ECE/TRANS/505 requirements, and Complying EN 1621 – 1

requirements Motorcyclist Clothing

• Approval Criteria:

o MPS: The test article shall not reveal any complete rupture for any of its

longitudinal elements. (European Committee for Standardization, 2012)

o ATD: It should not remain trapped in the system. There should be no complete

detachment of the ATD. ATD parts such as head, neck, limb, etc. shall not

become detached after the impact. However, the breaking of the ATD upper

extremity and shoulder assembly due to failure of the frangible screws after

impact is an exception. (European Committee for Standardization, 2012)

The full-scale crash tests are performed with an ATD sliding on its back with a helmet. The

specification requires the ATD to be the hybrid III 50

percentile male. The specification

evaluates the MPS performance based on two classes:

• Speed class – based on impact speed of tests.

• Severity level – based on biomechanical values obtained from ATD test measurements.

International Organization for Standardization 13232 Motorcycles-Test and Analysis

Procedures for Research Evaluation of Rider Crash Protection Devices Fitted to Motorcycles

The crash test agency is the International Organization for Standardization (ISO). The test

protocol standard consists of eight parts which are identified below from ISO 13232 (2005).

• Part 1: Definitions, symbols, and general considerations.

• Part 2: Definition of impact conditions in relation to accident data.

• Part 3: Motorcyclist anthropometric impact dummy.

• Part 4: Variables to be measured, instrumentation, and measurement procedures.

• Part 5: Injury indices and risk/benefit analysis.

• Part 6: Full-scale impact test procedures.

• Part 7: Standardized procedure for performing computer simulations of motorcycle

impact tests.

• Part 8: Documentation and reporting.

ISO 13232 Part 2 greatly expands the number of impact configurations and test conditions (e.g.,

impact speed) to determine the severity of a motorcycle impact against an opposing vehicle

(International Organization for Standardization, 2005). There are seven impact configurations

and test conditions specified by ISO 13232 Part 2, which differ for 1) Occupant Vehicle Contact

Location; 2) Relative Heading Angle, and 3) Occupant Vehicle/Motorcycle Speeds. In addition,

ISO 13232 Part 2 recommends a Hybrid III 50th percentile male ATD with specific

characteristics (e.g., sit/stand construction, standard non-sliding knees) and some additional

modifications (e.g., ATD head skins, frangible knee assembly, and leg retaining cables). See

Zellner et al. (1996) for a full list of additional ATD modifications.

FEMA Final report of the Motorcyclists and Crash Barriers Project, Federation of European

Motorcyclist's Associations

The testing agency was BASt, the German Federal Highway Research Institute, who conducted

work for FEMA (see FEMA, 2010). Their agency defined a test procedure for impact protectors

which evaluated the deceleration value during the impact against a protector. The evaluation

criteria was unique in that it specified a maximum of 60 g and, over 3 milliseconds, a measured

g of 40. The authors defined two different classes of devices. Class 1 devices are those with a

test impact speed of 12.4 mi/h (20 km/h) while Class 2 devices are those with an impact speed of

21.7 mi/h (35 km/h).

Australian/New Zealand Standard

The Australian/New Zealand standard (Standards Australia Limited/Standards New Zealand,

2015) consists of two portions that define requirements for road safety barrier systems. The first

portion focuses on both permanent and temporary safety barrier systems. These systems include

crash cushions, longitudinal barrier gates, longitudinal barriers, and terminals as examples. The

second portion focuses on permanent and temporary roadside devices specifically for safety.

These devices include examples such as bollards, pedestrian fences, attenuators affixed to truck

and trailers, and support structures and poles for roadside signs.

Australian data revealed that out of half of the motorcyclists who crashed into a barrier in an

upright position on a motorcycle, half of them slid on top (Grzebieta et al., 2013). Also, data

shows that majority of motorcyclists suffered from serious thorax injuries (Bambach et al.,

2012a). To address this situation, the Australian/New Zealand standard suggests that, apart from

the HIC as considered by other standards, additional thorax compression criterion testing should

be conducted. The Australian/New Zealand standard states that previous standards, such as the

Spanish standard, L.I.E.R. testing protocol, and the EN1317-8 involved an ATD sliding into a

barrier and did not consider motorcyclists impacting roadside barriers in an upright position.

Thus, the barriers suggested by other standards may be less effective in preventing rider injuries

while impacting barriers in the upright position. Newly retrofitted devices need to be crash tested

with motor vehicles since the design of these devices are centered around critical posts and

beams which can be less effective during barrier-motor vehicle collisions. Further research and

development is needed to understand the risks of riders impacting barriers in an upright position

and contacting the barrier on the top. It is noted that the Austroad research regarding road design

and safety barrier assessment process is similar to the Australian/New Zealand standard with the

exception that the Austroad guidelines provide specifications the variety of roadway and

roadside configurations where roadside barrier systems may be installed.

Development of New U.S. Standards and Protocols

As evidenced to this point, the U.S does not have any standards or protocols which address the

motorcycle safety issues for roadside barriers and, as a result, roadside safety barriers in the U.S.

are not tested and evaluated to determine the extent to which they would provide a benefit to

motorcyclists. It is recognized that the development of U.S.-based standards and protocols will

require extensive planning, research, and evaluation which is beyond the scope of the current

project and report. To facilitate future discussions that will lead to standards and protocols

development for roadside barriers that consider motorcyclist safety, the following configuration

considerations are identified. Specifically, it is recommended that both sliding and upright

impact configurations be developed to evaluate motorcycle friendly roadside barriers. The

following sections summarize the general considerations that should be examined relative these

two impact configurations.

Considerations for an Upright Impact Configuration

It is important to consider an upright impact configuration when developing a new standard for

mitigating injuries for motorcyclists while impacting barriers so that the incidence of head and

thorax injuries can be addressed (Grzebieta et al., 2013). Table 1 summarizes the testing

parameters, rational, and additional considerations that should be considered in the planning,

development, and research of roadside safety barriers testing standards and protocols in the U.S.

It is important to note that the Critical Impact Point (CIP) for a crash test should be decided

based on the type of the barrier used for testing. Since the barrier might be uniquely retrofitted

with MPS, it is important consider the critical location for each barrier. The critical location is

the location where the barrier provides highest probability for the test to fail The CIP can be

determined by either parametric evaluation through simulations or by determining the point of

maximum damage to the MPS and ATD. Further, it shall be determined so that the ATD has

maximum interaction with the MPS to evaluate crashworthiness of the system. This can support

a veridical test of the MPS ability to limit interaction of the ATD with discrete barrier elements

(e.g., posts).

Table 1. Upright Impact Configuration Evaluation Parameters, Selection Rational, and

Additional Considerations for Upright Motorcycle Testing and Evaluation Standard and

Protocols.

Testing

Parameters

Selection Rational

Additional Considerations

Impact Angle

The impact angle plays an

important role in defining the

trajectory of the rider and the

interaction with the impacted

barrier. In addition, it can play an

important role in determining

impact severity.

Potential sources would be real-world

crash databases of motorcycle impacts

against roadside hardware. A challenge

is to have complete accident

reconstruction of the vehicle kinematics

for these crashes, which would likely be

the best way to obtain the actual impact

angle. It might be possible that police

accident reconstruction is applied to

fatal crashes, but there is a need for non-

fatal crashes to also be examined.

Impact Speed

Impact speed is important to

consider since it will determine the

severity of the impact. Impact

speed will also determine the rider

behavior and interaction with the

system.

Potential sources would be real-world

crash databases of motorcycle impacts

against roadside hardware. Impact speed

can be determined by posted speed limit

on crash road sections. However, the

optimal method to determine exact

speed would be through complete crash

reconstruction.

Impact mode

The type of impact mode

(sliding/upright) of the rider

constitutes an essential input to

properly replicate the real world

rider’s impact trajectories. In

addition, the impact mode will

serve to identify the critical retrofit

aspects of the system investigated.

Potential sources include studies that

determine through crash data analysis

the upright impact mode.

Motorcycle Type

The type of motorcycle can play a

considerable role in determining

rider position while impacting a

barrier. Sports, traditional, touring,

and cruisers are examples of

motorcycle types.

Potential sources would include real-

world crash databases of motorcycle

impacts against roadside barriers that

specify motorcycle type.

Testing

Parameters

Selection Rational

Additional Considerations

ATD

An ATD is recommended to be

used for all tests due to its ability

to record and provide data on its

interaction with a crash barrier and

barrier performance.

Studies and standards which

recommend ATD to be used in crash

tests should be reviewed. The ATD type

which conforms to the U.S crash data

and represents an average U.S

motorcyclist should be used.

ATD Helmet

The helmet worn by an ATD used

in a crash test should represent an

average U.S motorcyclist. A

certified DOT helmet commonly

used by motorcyclists can be

employed.

Examine available data to identify the

particular type of certified helmet

primarily used in the U.S. and by riders.

ATD Clothing

Standard motorcyclist clothing

should be provided to represent an

average U.S motorcyclist.

Commonly used motorcyclist clothing

like leather jackets and pants have to be

used during testing.

Roadside

Hardware/Barrier

Type

The roadside barrier to be tested

should be should be identified and

selected carefully to understand

better the potential differences

between rider impacts for different

barrier type categories (e.g.,

concrete barriers, guardrails).

Available roadside crash data can be

used to determine the barrier types most

commonly used and resulting in

fatal/serious injuries with motorcycle

impacts.

MPS Evaluation

Criteria

It will be informative to have an

evaluation criteria which:

1) Tests barrier strength, which

could be longitudinal rail strength

in the case of a guardrails.

2) Judges interaction between an

ATD and the barrier impacted

(e.g., snagging or tearing of ATD

while impacting barriers).

3) Evaluates the ATD behavior by

maintaining biomechanical limits

for the safety of rider (e.g., limits

on HIC, neck forces and moments,

chest deflection, and thorax

injuries).

Potential resources can be current

standards or practices used to evaluate

ATD crash tests. Available standards

and criteria can be referred to determine

the ATD biomechanical limits.

Considerations for a Sliding Impact Configuration

The sliding impact configuration has been primarily addressed by European standards and

protocols for testing and evaluation of roadside barriers to improve crash outcomes for

motorcyclists. Standards (e.g., EN1317-8) are used by many of the roadside barrier

manufacturers to evaluate their systems for installation on a roadside. It will be important to

develop sliding impact configuration standards in the U.S. to evaluate those roadside barrier

systems deployed in the U.S. A sliding impact can occur in an actual crash after the rider is

ejected from the motorcycle some distance before impacting a barrier and slides across the

surface into a barrier element. Since a sliding configuration has been addressed by existing

motorcycle standards in Europe and elsewhere, data and suggestions from those efforts can

facilitate the development of U.S. standard and protocols.

FINITE ELEMENT ANALYSIS AND SIMULATION

The development and testing of roadside safety barriers as countermeasures to improve

motorcyclist safety has expanded beyond crash testing and ISPEs. Finite Element (FE) analysis

and simulation consists of computer modeling (e.g., simulation) of physical objects using finite

element method. This approach can be used to determine how physical objects, such as a

collision between a motorcycle and a roadside safety barrier, and is now an important resource

for researchers. FE is a relatively inexpensive and minimally time consuming compared to

traditional crash testing or ISPE approaches. FE also has the benefit of being able to examine a

wide variety of barriers and employ accepted crash testing standards and protocols. Another

advantage is that FE can be used to design MPS that address both sliding and upright impacting

motorcyclists. Further, FE can be helpful to determine risk associated with occupants from an

impact such as the risk for a rider (or ATD) due to barrier impact. The trajectory of the rider

(ATD) in the simulations can be judged which can facilitate an understanding of the behavior of

motorcyclist in actual crashes.

Although FE and simulation are relatively new areas of study, several studies have been

conducted using computer simulations as a tool to perform FE motorcycle barrier crash tests with

variety of impact configurations. A few of these studies are discussed below to illustrate the

efforts and usefulness of FE simulations in crash testing industry.

Schulz et al. (2016) (see also Schulz, 2017) developed an FE model of a motorcycle (Kawasaki

Ninja 500 R) (see Figure 20) through a reverse engineering technique in which each part of the

motorcycle was disassembled, scanned into a three dimensional computer model, and was then

validated using FE for initial robustness. The model was then used in a project by Dobrovolny et

al. (2019) to conduct motorcycle barrier crash simulations. The model was used to conduct an

upright impact crash test simulation with a retrofitted guardrail system which was then followed

by a full scale crash test. Similarly De Franco (2016) conducted a study to design a motorcycle-

friendly roadside safety barrier. One of the phases of that study addressed the performance of the

FE motorcycle model and also performed numerical validation crash tests using LS DYNA.

Institute

Figure 20. Finite Element Computer Model Developed by

Schulz et al. (2016).

Similarly Mongiardini et al. (2017) conducted a study to develop a Finite Element (FE) computer

model of a motorcycle with the purpose being to develop a model to investigate upright

motorcycle impact characteristics when impacting different types of roadside safety barriers. The

FE model of Suzuki GSX-650F sport-touring was developed and simulations were performed

using an ATD. Their model showed good correlation when validated by comparing the

simulation results with experimental test results.

A study by Dobrovolny et al. (2019) focused on the development of a concrete containment

barrier to address the upright motorcycle containment problem associated with concrete barriers.

For this study, FE simulations were conducted using LS DYNA to perform several upright

motorcycle-barrier crash tests. FE simulation results exhibited acceptable performance which

suggested the containment barrier option among multiple other options for full scale crash testing

would be beneficial. The containment and redirection abilities of the barrier were judged based

on the upright motorcycle-barrier simulations. Similarly, Berg et al. (2005) conducted full scale

crash tests and upright FE simulations using simulation software (i.e., MADYMO by Siemens

Digital Industry). A full scale crash test was employed to validate a motorcycle barrier model

which was then used to understand impact characteristics with a concrete barrier and wire rope

barrier at different impact speeds. Their results indicated that the injury risk was high for

motorcyclists when impacting a concrete barrier or wire rope barriers. Ptak et al. (2019) used LS

DYNA for FE simulations with a MADYMO ATD model to determine motorcycle injury risks

due to barrier impact. Motorcycle, helmet, and barrier models were represented by LS DYNA

while the 50

percentile Hybrid III dummy was modeled through MADYMO. Upright impact

simulations were conducted with an energy absorbing motorcycle barrier. Although the results

indicated less effective energy absorption with a barrier, their work indicated the utility of

simulation for saving costs and resources compared to an actual crash test.

A paper by Atahan et al. (2018) discusses results obtained after performing motorcycle

simulations and full scale crash tests with a continuous MPS. The MPS was evaluated with LS

DYNA simulation first and then full scale crash tests were performed to determine

crashworthiness of the MPS. The test was performed per EN 1317-8 specifications. A sliding

ATD configuration was used to conduct the simulations and results showed acceptable results.

Following the simulations, the full scale crash test results indicate that the MPS was able to

satisfy crashworthiness criteria with minimal injury risk to motorcyclist.

At the field of FE continues to develop, it is anticipated that most initial roadside barrier testing

will be conducted in simulation first to determine the optimal design and then only conduct a real

world crash test to validate the results. This approach will allow for a relatively quick and

iterative design approach.

CONCLUSION

The purpose of roadside barrier systems is to reduce the rate injurious and fatal crashes by

controlling and mitigating crash forces. While barrier systems have been designed and proven to

be beneficial for motor vehicles they do not currently address the problems associated with

motorcycle crashes. For example, while a guardrail can mitigate the effects of a motor vehicle

crash quite successfully, the same barrier system is associated with motorcyclists sliding along

the top of the barrier and also with hitting their head on the discrete posts behind the beam that

support the barrier. These crash characteristics can lead to serious upper body and head injuries.

In essence, existing barrier designs may be beneficial for errant vehicles but not for

motorcyclists.

The synthesis of research presented in this report concludes that motorcyclists are more

vulnerable than errant vehicles of motor vehicles and that motorcyclists are more likely to be

severely injured when they crash into a barrier system. This research indicates that the body

position of a motorcyclists and the type of barrier can significantly influence crash

characteristics. In particular, concrete barrier systems were more likely to be associated with

motorcyclists vaulting over the system in contrast to a guardrail which was more likely to be

associated with motorcyclists sliding into the barrier system. The synthesis also found that

helmet use does not guarantee a risk free impact between motorcyclists and barriers largely due

to the fact that a motorcyclists’ helmeted head may still strike a discrete post. Discrete posts (and

other elements such as beams) pose challenges in other ways including motorcyclists striking

them as they slide under a guardrail or in some instances causing a rider to vault over the barrier

and strike a post.

Addressing the challenges associated with barrier systems is critical for reducing the rate of

injurious and fatal motorcyclist crashes. This synthesis summarized several new barriers and

retrofit systems currently used or under development that are specifically intended to improve

motorcyclist safety in addition to retaining the existing benefit for motor vehicles. These systems

included a top rail that allows a motorcyclist to slide along the top of a barrier without the risk of

striking a discrete post, a lower rub rail that prevents a motorcyclist from impacting a discrete

post under the main guardrail, and a chain fence system with offset support posts that redirects a

motorcyclist and prevents that from striking a support post. While no barrier system is 100

percent effective at eliminating motorcyclists’ injuries and fatalities and these new designs may

prompt an array of secondary issues, they are widely seen as offering a significant benefit to

motorcyclists in the event of a crash involving a barrier. Research and installation efforts by the

California, North Carolina, and Texas DOTs offer a glimpse into the efficacy of MPS barrier

systems; however, it is noted that their research results are a first step in the longer journey of

improving outcomes for motorcyclists when involved in barrier crashes.

The synthesis summarized research gaps that should be addressed to improve motorcycle-barrier

crash safety. These gaps and research needs include:

• Developing standards or protocols to test an upright motorcycle impact configuration.

• Develop standards for evaluating barriers for sliding test configurations.

• Develop guidelines for addressing proper testing for retrofit barriers (use, adopt, modify

European standards).

• Develop IPSE testing guidance and protocols to support DOTs efforts to evaluate the

efficacy of barrier systems.

• Develop placement guidance for installation at locations which are critical to

motorcyclist safety.

• Develop a largescale motorcycle crash database.

Finally, it is critical to understand the crash characteristics and injury outcomes when a

motorcyclist impacts a roadside barrier so that barrier designs can be improved and so that

practitioners are able to make sound judgements regarding their installation. Currently, there are

no U.S. standards in place to guide testing efforts. The final portion of this report summarized

testing parameters to be considered for both upright and sliding impacts into barriers that should

be investigated during the planning, development, and research of testing standards in the U.S.

ACKNOWLEDGMENTS

This report is a result of FHWA's leadership in the area of motorcycle safety countermeasures

toward creating information and resources for practitioners. The Project Team gratefully

acknowledges the guidance and feedback provided by Guan Xu and Abdul Zineddin, both of

FHWA.

The Project Team also acknowledges the project FHWA Technical Panel which includes the

following individuals:

• Dick Albin

• Eduardo Arispe

• Yusuf Mohamedshah

• Aimee Zhang

Project Stakeholder Engagement Working Group members provided excellent guidance and

feedback throughout this phase of the project. The members include the following individuals:

• Clayton Chen | Federal Highway Administration

• John Corbin | Federal Highway Administration

• Jack Cunningham | Kansas State University

• Eric Fitzsimmons | Kansas State University

• Michael Fox | National Transportation Safety Board

• Dillon Funkhouser | University of Michigan Transportation Research Institute

• James Harris | JT Harris and Associates

• Elizabeth Hilton | Federal Highway Administration

• LaCheryl Jones | National Highway Traffic Safety Administration

• Jane Lundquist | Texas Department of Transportation

• Maurice Manness | Texas Department of Transportation

• Stergios Mavromatis | National Technical University of Athens

• Adriane McRae | Louisiana Department of Transportation

• Andrew Mergenmeier | Federal Highway Administration

• Joel Provenzano | Florida Department of Transportation

• Jerry Roche | Federal Highway Administration

• Matt Romero | Oklahoma Department of Transportation

• Kenny Seward | Oklahoma Department of Transportation

• Craig Shankwitz | Montana State University

• Jeffrey Shaw | Federal Highway Administration

• Terry Smith | Dynamic Research

• Eric Teoh | Insurance Institute for Highway Safety

• Kathryn Weisner | Federal Highway Administration

• Kathryn Wochinger | National Highway Traffic Safety Administration

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