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 

22312

19. Security Classif.(of this report)

Unclassified

20. Security Classif.(of this page)

Unclassified

21. No. of Pages

64

22. Price

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

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

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

References.................................................................................................................................... 49
v

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
vi

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)
1

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 motorcyclerelated 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 
2

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 preimpact 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 motorcyclebarrier 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.
3

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 motorcyclebarrier 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. 
4

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 
5

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.
6

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.
7

©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 costeffectiveness 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 
8

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 motorcyclebarrier 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. 
9

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 
10

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 
11

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.
12

©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
13

©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.
14

©Texas A&M Transportation 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 
15

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).
16

©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, 
17

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
18

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
19

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 
20

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. 
21

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 
22

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.
23

©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 
24

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
25

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.
26

©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.
27

©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 
28

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 
29

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 motorcyclefriendly 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 
30

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 costeffective 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. 
31

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.
32

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 
33

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 
34

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,
35

• 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 
36

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 
37

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:
38

• Impact Speed: 60 km/h - 37.3 mi/h; and 70 km/h (43.5 mi/h)

• Impact Angle: 30°

• ATD: Hybrid III 50th 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 50th 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 50th percentile male. The specification 

evaluates the MPS performance based on two classes:

• Speed class – based on impact speed of tests.
39

• 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 
40

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 
41

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 nonfatal 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 realworld crash databases of motorcycle 

impacts against roadside barriers that

specify motorcycle type.
42

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.
43

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 motorcyclefriendly 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. 
44

©Texas A&M Transportation 

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 50th 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. 
45

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.
46

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.
47

• 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.
48

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
49

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