MAKING OUR 

ROADS SAFER

28 Proven Safety Countermeasures that offer signif icant 

and measurable impacts to improving safety

https://safety.fhwa.dot.gov/

One 

Countermeasure 

at a Time
Technical Report Documentation Page

1. REPORT NO.

FHWA-SA-21-071

2. GOVERNMENT ACCESSION

NO.

3. RECIPIENT'S CATALOG NO.

4. TITLE AND SUBTITLE

Making Our Roads Safer | One Countermeasure at a Time

5. REPORT DATE

October 2021

6. PERFORMING ORGANIZATION

CODE

7. AUTHOR(S)

Matt Albee, Phillip Bobitz

8. PERFORMING ORGANIZATION

REPORT NO.

9. PERFORMING ORGANIZATION NAME & ADDRESS 10. WORK UNIT NO.

11. CONTRACT OR GRANT NO.

DTFH6116D00040-

693JJ320F000262

VHB 

940 Main Campus Dr Ste 500 

Raleigh, NC 27606

12. SPONSORING AGENCY NAME AND ADDRESS

Federal Highway Administration Office of Safety

1200 New Jersey Ave., SE 

Washington, DC 20590

13. TYPE OF REPORT AND PERIOD

Final Report, July 2020 – August 

2021

14. SPONSORING AGENCY CODE

HSST

15. SUPPLEMENTARY NOTES

The Contract Manager for this report was Phillip Bobitz (FHWA Office of Safety). Matt Albee (VHB) was the 

Principal Investigator.

An FHWA Technical Oversight Working Group included: Dick Albin, Usman Ali, Roya Amjadi, RosemarieAnderson, 

Eduardo Arispe, Tori Brinkly, Joe Cheung, Becky Crowe, Mike Griffith, Ken Kochevar, MichaelMatzke, Tara 

McLoughlin, Laura Mero, Anyesha Mookherjee, Elliott Moore, Norah Ocel, Tamara Redmon,Jerry Roche, Cate 

Satterfield, Jeff Shaw, Keith Sinclair, Karen Timpone, Guan Xu, and Abdul Zineddin.

16. ABSTRACT

The Proven Safety Countermeasure Initiative (PSCi) is a collection of 28 countermeasures and strategieseffective 

in reducing roadway fatalities and serious injuries on our Nation’s highways. Transportationagencies are strongly 

encouraged to consider widespread implementation of PSCs to accelerate theachievement of local, State, and 

National safety goals. This booklet provides 1-page handouts for all 28PSCs, broken into the focus areas of speed 

management, roadway departure, intersections,pedestrians/bicyclists, and crosscutting for countermeasures that 

apply across categories.

17. KEY WORDS

safety, countermeasures, speed management, roadway departure, 

intersections, pedestrian, bicyclist

18. DISTRIBUTION STATEMENT

No restrictions.

19. SECURITY CLASSIF. (OF

THIS REPORT) Unclassified

20. SECURITY CLASSIF. (OF

THIS PAGE) Unclassified

21. NO. OF

PAGES 33

22. PRICE

Form DOT F 1700.7 (8-72) Reproduction of form and completed page is authorized.
SPEED MANAGEMENT

Speed Safety 

Cameras Variable Speed Limits Appropriate Speed Limits for All Road Users

ROADWAY DEPARTURE

Wider Edge Lines Enhanced Delineation 

for Horizontal Curves

Longitudinal Rumble 

Strips and Stripes on 

Two-Lane Roads

SafetyEdgeSM

Roadside Design 

Improvements at 

Curves

Median Barriers

INTERSECTIONS

Backplates with 

Retroreflective 

Borders

Corridor Access 

Management

Dedicated Left- and 

Right-Turn Lanes at 

Intersections

Reduced Left-Turn 

Conflict Intersections Roundabouts

Systemic Application 

of Multiple Low-Cost 

Countermeasures at 

Stop-Controlled 

Intersections

Yellow Change 

Intervals

PEDESTRIANS/BICYCLES

Crosswalk Visibility 

Enhancements Bicycle Lanes

Rectangular Rapid 

Flashing Beacons 

(RRFB)

Leading Pedestrian 

Interval

Medians and Pedestrian 

Refuge Islands in Urban 

and Suburban Areas

Pedestrian Hybrid 

Beacons

Road Diets (Roadway 

Reconfiguration) Walkways

Crosscutting

Pavement Friction 

Management Lighting Local Road Safety Plans

Road Safety Audit
Introduction

Widespread use of the 28 Proven Safety Countermeasures (PSCs) identified in this booklet can 

offer significant, measurable impacts as part of any agency’s approach to improving safety. 

These strategies are designed for all road users and all kinds of roads—from rural to urban, 

from high-volume freeways to less traveled two-lane State and county roads, from signalized 

crossings to horizontal curves, and everything in between. Each countermeasure addresses 

at least one safety focus area – speed management, intersections, roadway departures, or 

pedestrians/bicyclists – while others are crosscutting strategies that address multiple safety 

focus areas.

Between 2016 and 2020, 85 percent1 of all public highway fatalities occurred on Federal-aid 

highways, which represent 25 percent2 of the entire public highway network. FHWA’s partner 

agencies have invested in highway safety through the Highway Safety Improvement Program 

(HSIP), which provides targeted safety funding that is eligible for use on all public roads. 

However, this dedicated funding source represents only about 6 percent of the total Federalaid program.3 Every transportation project, whether or not the specific project purpose is 

safety related, is a new opportunity to save lives on our roadways. The FHWA’s Proven Safety 

Countermeasures are eligible under most Federal-aid highway funding programs, and 

can support state, local, and tribal agency efforts to effectively accomplish goals to reduce 

fatalities and serious injuries. These countermeasures should serve as the basis for what 

agencies consider and implement when designing any highway project to improve safety.

To assist practitioners with determining the most appropriate PSC for their location of interest, 

the PSC webpage includes a filter tool that allows users to obtain a tailored listing of potential 

PSCs. Users answer questions regarding area types, functional classification, traffic volumes, 

issue identified, targeted crash types, and other information to receive a list of PSCs meeting 

thecriteria. This search function is intended to better serve practitioners, including those with 

limited safety background, when identifying and considering treatments and strategies that 

can improve safety as part of their program or project.

The PSCs can support agencies with implementation of the Safe System Approach, which 

seeks to build and reinforce multiple layers of protection to both prevent crashes from 

happening and minimize the harm caused to those involved when crashes do occur. 

Implementing a Safe System Approach requires collaborative engagement among a 

diverse group of stakeholders to increase safety for all road users. Accordingly, agencies 

should consider how the PSCs and National Highway Traffic Safety Administration’s (NHTSA) 

Countermeasures That Work4 can create a system with redundancies in place to protect all 

road users. Reaching our goal of zero deaths and serious injuries requires all of us to take 

ownership in safety. Together, we can consider the safety needs at every stage of the project 

development process, the safety impact of every investment decision, and the appropriate 

safety countermeasures for every Federal-aid project.

1 NHTSA Fatality Analysis Reporting System (FARS) 2016-2020 Final

2 FHWA Highway Statistics 2022 (https://www.fhwa.dot.gov/policyinformation/statistics/2022/hm16.cfm)

3 Federal-aid apportioned programs under the Infrastructure Investment and Jobs Act (IIJA)

(https://www.fhwa.dot.gov/bipartisan-infrastructure-law/funding.cfm)

4 Countermeasures That Work (https://www.nhtsa.gov/book/countermeasures/countermeasures-that-work)
Speed 

Safety Cameras 

Safe Speeds is a core principle of the Safe System Approach since humans are less 

likely to survive high-speed crashes. Enforcing safe speeds has been challenging; 

however, with more information and tools communities can make progress in 

reducing speeds. Agencies can use speed safety cameras (SSCs) as an effective 

and reliable technology to supplement more traditional methods of enforcement, 

engineering measures, and education to alter the social norms of speeding. SSCs 

use speed measurement devices to detect speeding and capture photographic or 

video evidence of vehicles that are violating a set speed threshold. 

Applications

Agencies should conduct a network 

analysis of speeding-related crashes 

to identify locations to implement 

SSCs. The analysis can include scope 

(e.g., widespread, localized), location 

types (e.g., urban/suburban/rural, 

work zones, residential, school zones), 

roadway types (e.g., expressways, 

arterials, local streets), times of day, and 

road users most affected by speedrelated crashes (e.g., pedestrians, 

bicyclists).

SSCs can be deployed as: 

• Fixed units—a single, stationary

camera targeting one location.

• Point-to-Point (P2P) units—multiple

cameras to capture average speed

over a certain distance.

• Mobile units—a portable camera,

generally in a vehicle or trailer.

The table below describes suitable 

circumstances for SSC deployment.1

Considerations

• SSCs can produce a crash reduction

upstream and downstream, thus

generating a spillover effect.2

• Public trust is essential for any type of

enforcement. With proper controls in

place, SSCs can offer fair and

equitable enforcement of speeding,

regardless of driver age, race, gender,

or socio-economic status. SSCs should

be planned with community input and

equity impacts in mind.

• Using both overt (i.e., highly visible)

and covert (i.e., hidden) enforcement

may encourage drivers to comply with

limits everywhere, not only at sites they

are aware are enforced.

• Agencies should conduct

evaluations regularly to determine if

SSCs are accomplishing safety goals

and whether changes in strategy,

scheduling, communications, or public

engagement are necessary.

• Agencies should conduct a legal

and policy review to determine if SSCs

are authorized within a jurisdiction and

how the authorization and other traffic

laws will affect a SSC program.

• Agencies should develop an SSC

program plan with consideration of

the USDOT SSC guidelines for planning,

public involvement, stakeholder

coordination, implementation,

maintenance, evaluation, etc.3

FHWA-SA-21-070

Fixed units can reduce 

crashes on urban 

principal arterials up to:

for all 

crashes. 54% 4

for injury 

crashes. 48% 4

For more information on this 

and other FHWA Proven 

Safety Countermeasures, 

please reference the: 

Speed Safety Camera Program 

Planning and Operations Guide.

Safety Benefits:

Considerations for Selection Fixed P2P Mobile

Problems are long-term and site-specific. X X —

Problems are network-wide, and shift based on enforcement efforts. — — X

Speeds at enforcement site vary largely from downstream sites. — X X

Overt enforcement is legally required. X X X

Sight distance for the enforcement unit is limited. X X —

Enforcement sites are multilane facilities. X X —

1 Speed Safety Camera Program Planning and Operations Guide. FHWA, (2023). 

2 (CMF ID: 7718) Montella et al. “Effects on speed and safety of point-to-point speed enforcement systems”. 

Accident Analysis and Prevention, Vol. 75, (2015). Note that this is an international study.

3 Speed Enforcement Camera Systems Operational Guidelines. NHTSA, (2008).

4 (CMF ID: 2915,2921) Shin et al. “Evaluation of the Scottsdale Loop 101 automated speed enforcement 

demonstration program.” Accident Analysis and Prevention, Vol. 41, (2009).

5 (CMF ID: 7582) Li et al. “A Before-and-After Empirical Bayes Evaluation of Automated 

Mobile Speed Enforcement on Urban Arterial Roads.” Presented at the 94th Annual 

Meeting of the Transportation Research Board, Paper No. 15-1563, Washington, D.C., (2015). 

Note that this is an international study.

6 Automated Speed Enforcement Program Report 2014-2017. New York City DOT, (2018).

In New York City, fixed units 

reduced speeding in school 

zones up to 63% during 

school hours.6

P2P units can reduce crashes on 

urban expressways, freeways, 

and principal arterials up to:

for fatal and injury crashes.2

37%

Mobile units can reduce 

crashes on urban principal 

arterials up to:

for fatal and injury crashes.5

20%

The contents of this Fact Sheet do not have the 

force and effect of law and are not meant to 

bind the public in any way. This Fact Sheet is 

intended only to provide clarity regarding existing 

requirements under the law or agency policies.

OFFICE OF SAFETY

Proven Safety 

Countermeasures
Variable Speed 

Limits

Selecting appropriate speed limits on roadways is important in maintaining 

a safe and efficient transportation network. Speed limits are established with 

an engineering study based on inputs like traffic volumes, operating speeds, 

roadway characteristics, and crash history. However, conditions on the roadway 

are susceptible to change in a short amount of time (e.g., congestion, crashes, 

weather). Drivers typically determine their operating speeds under normal 

weather conditions on a straight roadway section with good pavement quality 

and adequate sight distances. If ideal conditions do not exist and the roadway 

does not meet the driver’s expectations, there is a greater chance that a driver 

error could result in a crash. Providing variable speeds limits (VSLs) capable of 

adapting to changing circumstances could reduce crash frequency and severity.

Speed management strategies, including VSLs, are integral to the Safe Speeds 

element of the Safe System Approach. Because humans are unlikely to survive 

high-speed crashes, VSLs reduce speeds so that human injury tolerances are 

accommodated in three ways: improving visibility, providing additional time for 

drivers to stop, and reducing impact forces. 

Applications

VSLs use prevailing information on the 

roadway, like traffic speed, volumes, 

weather, and road surface conditions, 

to determine appropriate speeds 

and display them to drivers. This 

strategy improves safety performance 

and traffic flow by reducing speed 

variance (i.e., improving speed 

harmonization). VSLs may also improve 

driver expectation by providing 

information in advance of slowdowns 

and potential lane closures, which 

could reduce the probability for 

secondary crashes. VSLs can mitigate 

adverse weather conditions or to slow 

faster-moving traffic as it approaches 

a queue or bottleneck.

Agencies can implement VSLs for 

the following applications:

CONGESTION INCIDENTS

WORK ZONES INCLEMENT WEATHER

Considerations 

• Particularly effective on urban and

rural freeways and high-speed arterials

with posted speed limits greater than

40 mph.

• Often implemented as part of Active

Traffic Management (ATM) plans

or incorporated into existing Road

Weather Information Systems.

• When used with ATM, VSLs can

mitigate rear-end, sideswipe,

and other crashes on high-speed

roadways.

• May be implemented as a regulatory

and/or an advisory system.

• Can be applied to an entire

roadway segment or individual lanes.

Source: WSDOT

1 (CMF ID: 11002,11005,11003) Avelar et al. Developing Crash Modification Factors 

FHWA-SA-21-054 for Variable Speed Limit. FHWA, (2020).

OFFICE OF SAFETY

Proven Safety 

Countermeasures

Safety Benefits:

VSLs can reduce crashes 

on freeways up to:

34%

for total crashes.1

65%

for rear-end crashes.1

51%

for fatal and injury crashes.1

Benefit/Cost Ratios 

range between1

9:1- 40:1

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter 

measures and https://

highways.dot.gov/safety/

speed-management/reference-materials.
Appropriate Speed 

Limits for All Road Users

There is broad consensus among global roadway safety experts that speed control 

is one of the most important methods for reducing fatalities and serious injuries. 

Speed is an especially important factor on non-limited access roadways where 

vehicles and vulnerable road users mix. 

A driver may not see or be aware of the conditions within a corridor, and may 

drive at a speed that feels reasonable for themselves but may not be for all users 

of the system, especially vulnerable road users, including children and seniors. A 

driver traveling at 30 miles per hour who hits a pedestrian has a 45 percent chance 

of killing or seriously injuring them.1

 At 20 miles per hour, that percentage drops 

to 5 percent.1

 A number of cities across the United States, including New York, 

Washington, Seattle and Minneapolis, have reduced their local speed limits in 

recent years in an effort to reduce fatalities and serious injuries, with most having to 

secure State legislative authorization to do so.

States and local jurisdictions should set appropriate speed limits to reduce the 

significant risks drivers impose on others—especially vulnerable road users—and 

on themselves. Addressing speed is fundamental to the Safe System Approach 

to making streets safer, and a growing body of research shows that speed limit 

changes alone can lead to measurable declines in speeds and crashes.2

 

Applications

Posted speed limits are often the same 

as the legislative statutory speed limit. 

Agencies with designated authorities to 

set speed limits, which include States, 

and sometimes local jurisdictions, can 

establish non-statutory speed limits or 

designate reduced speed zones, and 

a growing number are doing so. While 

non-statutory speed limits must be based 

on an engineering study, conducted in 

accordance with the Manual on Uniform 

Traffic Control Devices (MUTCD) involving 

multiple factors and engineering 

judgment, FHWA is also encouraging 

agencies to use the following:3

• Expert Systems tools.

o USLIMITS2.

o NCHRP 966: Posted Speed Limit

Setting Procedure and Tool.

• Safe System approach.

Based on international experience

and implementation in the United

States, the use of 20 mph speed zones

or speed limits in urban core areas

where vulnerable users share the road

environment with motorists may result in

further safety benefits.4

Considerations

When setting a speed limit, agencies 

should consider a range of factors such 

as pedestrian and bicyclist activity, crash 

history, land use context, intersection 

spacing, driveway density, roadway 

geometry, roadside conditions, roadway 

functional classification, traffic volume, 

and observed speeds.

To achieve desired speeds, agencies 

often implement other speed 

management strategies concurrently 

with setting speed limits, such as selfenforcing roadways, traffic calming, 

and speed safety cameras. Additional 

information is in the following FHWA 

resources:

• FHWA Speed Management website.

• Self-Enforcing Roadways:

A Guidance Report.

• Noteworthy Speed

Management Practices.

• Jurisdiction Speed Management

Action Plan Development Package.

• Traffic Calming ePrimer.

FHWA-SA-21-034

1 Reducing the speed limit to 20 mph in urban areas: Child deaths and injuries would be decreased.

2 Lowering the speed limit from 30 to 25 mph in Boston: effects on vehicle speeds.

3 FHWA’s Methods and Practices for Setting Speed Limits: An Informational Report, (2012).

4 Recommendations of the Academic Expert Group for the 3rd Global Ministerial 

Conference on Road Safety.

5 https://safety.fhwa.dot.gov/speedmgt/ref_mats/fhwasa20047/sec8.cfm#foot813 

6 Safety and Operational Impacts of Setting Speed Limits below 

Engineering Recommendations.

OFFICE OF SAFETY

Proven Safety 

Countermeasures

Safety Benefits:

Traffic fatalities in the City 

of Seattle decreased 

26 percent after the 

city implemented 

comprehensive, city-wide 

speed management 

strategies and 

countermeasures inspired 

by Vision Zero. This included 

setting speed limits on 

all non-arterial streets at 

20 mph and 200 miles of 

arterial streets at 25 mph.5

One study found that 

on rural roads, when 

considering other relevant 

factors in the engineering 

study along with the speed 

distribution, setting a speed 

limit no more than 5 mph 

below the 85th-percentile 

speed may result in fewer 

total and fatal plus injury 

crashes, and lead to drivers 

complying closely with the 

posted speed limit.6 

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter 

measures and https://

highways.dot.gov/safety/

speed-management/ 

reference-materials.
37%

for non-intersection, fatal 

and injury crashes on rural, 

two-lane roads.2

FHWA-SA-21-055

Wider Edge Lines 

Roadway departures account for over half of all traffic fatalities in the United 

States. If drivers cannot clearly identify the edge of the travel lanes and see 

the road alignment ahead, the risk of roadway departure may be greater. 

Wider edge lines enhance the visibility of travel lane boundaries compared 

to traditional edge lines. Edge lines are considered “wider” when the marking 

width is increased from the minimum normal line width of 4 inches to the 

maximum normal line width of 6 inches.1

Applications

Wider edge lines increase drivers’ 

perception of the edge of the 

travel lane and can provide a 

safety benefit to all facility types 

(e.g., freeways, multilane divided 

and undivided highways, two-lane 

highways) in both urban and rural 

areas.2

 Wider edge lines are most 

effective in reducing crashes on 

rural two-lane highways, especially 

for single-vehicle crashes.3 Agencies 

should also consider implementing 

a systemic approach to wider edge 

line installation based roadway 

departure crash risk factors. Potential 

risk factors for two-lane rural roads 

include:

• Pavement and shoulder widths.

• Presence of curves.

• Traffic volumes.

• History of nighttime crashes.

Considerations

• Wider edge lines are relatively

low cost.

• Wider edge lines can be

implemented using existing

equipment during maintenance

procedures like re-striping and

resurfacing, with the only cost

increase being the additional

material.

• Paint may have a lower initial cost,

but more durable materials (e.g.,

thermoplastic) may result in a

lower life cycle cost based on their

longer service life.

• As the number of automated

vehicles increases on roadways,

wider edge lines may provide

better guidance for these

vehicles’ sensors.

Source: Texas Transportation Institute

22%

for fatal and injury crashes 

on rural freeways.3

 1 Manual on Uniform Traffic Control Devices (MUTCD), Section 3A.04. FHWA, (2023).

2 (CMF ID: 4737) Park et al. “Safety effects of wider edge lines on rural, two-lane highways. 

” Accident Analysis and Prevention Vol. 48, pp.317-325, (2012). 

3 Potts et al. Benefit/Cost Evaluation of MoDOT’s Total Striping and Delineation 

Program: Phase II. Missouri Department of Transportation, (2011).

4 Abdel-Rahim et al. Safety Impacts of Using Wider Pavement Markings 

on Two-Lane Rural Highways in Idaho. Idaho Transportation Department, (2018).

25:1

Benefit Cost Ratio

for fatal and serious injury 

crashes on two-lane rural 

roads.4

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter

measures and https://high 

ways.dot.gov/safety/other/

visibility/pavement-markings.

Wider edge lines can 

reduce crashes up to:

Safety Benefits:

OFFICE OF SAFETY

Proven Safety 

Countermeasures
Enhanced Delineation 

for Horizontal Curves

Enhanced delineation at horizontal curves includes a variety of potential 

strategies that can be implemented in advance of or within curves, in 

combination, or individually.

Potential Strategies In Advance of Curve Within Curve

Pavement markings (standard width 

or wider) 

In-lane curve warning pavement markings 

Retroreflective strips on sign posts

Delineators

Chevron signs

Enhanced Conspicuity (larger, fluorescent, 

and/or retroreflective signs)

Dynamic curve warning signs 

(including speed radar feedback signs)

Sequential dynamic chevrons

Enhanced delineation treatments 

can alert drivers to upcoming curves, 

the direction and sharpness of the 

curve, and appropriate operating 

speed. 

Agencies can take the following 

steps to implement enhanced 

delineation strategies:

1. Review signing practices and

policies to ensure they comply

with the Manual on Uniform

Traffic Control Devices (MUTCD)

principles of traffic control devices.

Consistent practice for similar

curves sets the appropriate driver

expectancy.

2. Use the systemic approach to

identify and treat problem curves.

For example, Minnesota uses risk

factors that include curve radii

between 500 and 1,200 ft, traffic

volumes between 500 and 1,000

vehicles per day, intersection in

the curve, and presence of a

visual trap.1

3. Match the appropriate strategy

to the identified problem(s),

considering the full range of

enhanced delineation treatments.

Once the MUTCD requirements and

recommendations have been met,

an incremental approach is often

beneficial to avoid excessive cost.

FHWA-SA-21-035

Chevron signs with retroreflective strips on sign 

posts installed along a curve. Source: FHWA

Safety Benefits:

Chevron Signs

25% reduction in nighttime

crashes.1

16% reduction in

non-intersection fatal and 

injury crashes.2

Oversized Chevron Signs

15% reduction in fatal and

injury crashes.3

Sequential Dynamic Chevrons

60% reduction in fatal and

injury crashes.4

In-Lane Curve Warning 

Pavement Markings

35 - 38% reduction in

all crashes.5

New Fluorescent Curve Signs 

or Upgrade Existing Curve 

Signs to Fluorescent Sheeting

18% reduction in nonintersection, head-on, 

run-off-road, and sideswipe 

in rural areas.1

1 (CMF ID: 2439,2431,2432) Albin et al. Low-Cost Treatments for Horizontal Curve Safety 2016. FHWA-SA-15-084, (2016).

2 (CMF ID: 2438) Srinivasan et al. Safety Evaluation of Improved Curve Delineation. FHWA-HRT-09-045, (2009).

3 (CMF ID: 8978) Lyon et al. Safety Evaluation of Two Curve Warning Treatments: In-Lane Curve Warning 

Pavement Markings and Oversized Chevron Signs. Presented at the 96th TRB Annual 

Meeting, Paper No. 17-00432, (2017). 

4 (CMF ID: 10362) Hallmark, S. Evaluation of Sequential Dynamic Chevrons on Rural Two-lane 

Highways. FHWA, (2017).

5 (CMF ID: 10312,9167) Donnell et al. Reducing Roadway Departure Crashes at Horizontal 

Curve Sections on Two-lane Rural Highways. FHWA-SA-19-005, (2019).

OFFICE OF SAFETY

Proven Safety 

Countermeasures

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter 

measures and https://high 

ways.dot.gov/safety/rwd/

keep-vehicles-road/horizon 

tal-curve-safety.
FHWA-SA-21-036

Longitudinal Rumble 

Strips and Stripes 

Longitudinal rumble strips are milled or raised elements on the pavement 

intended to alert drivers through vibration and sound that their vehicle has 

left the travel lane. They can be installed on the shoulder, edge line, or at or 

near the center line of an undivided roadway.

Rumble stripes are edge line or center line rumble strips where the 

pavement marking is placed over the rumble strip. This can increase the 

visibility and durability of the pavement marking during wet, nighttime 

conditions, and can improve the durability of the marking on roads with 

snowplowing operations.

1 Himes, S., and McGee, H. Decision Support Guide for the Installation of Shoulder and Center Line Rumble Strips 

on Non-Freeways. Federal Highway Administration Report No. FHWA-SA-16-115. (August 2016).

2 Bedsole et al. Did You Hear That? Public Roads Magazine, Volume 80, No. 4. FHWA Publication 

No. FHWA-HRT-17-002, (2017). 

3 NCHRP Synthesis 339: Centerline Rumble Strips – A Synthesis of Highway Practices, (2005

4 (CMF ID: 3358, 3356, 3425, 3648) NCHRP Report 641: Guidance for the Design 

and Application of Shoulder and Centerline Rumble Strips, (2009).

With roadway departure crashes 

accounting for more than half of 

the fatal roadway crashes annually 

in the United States, rumble strips 

and stripes are designed to address 

these crashes by alerting distracted, 

drowsy, or otherwise inattentive 

drivers who drift from their lane. They 

are most effective when deployed 

systemically.

Transportation agencies should 

consider milled center line rumble 

strips (including in passing zone 

areas) and milled edge line 

or shoulder rumble strips with 

bicycle gaps for systemic safety 

projects, location-specific corridor 

safety improvements, as well as 

reconstruction or resurfacing 

projects.

Considerations

• Rumble strips are relatively lowcost, and economic analyses have

indicated benefit/cost ratios that

exceed 100.1

• Where rumble strips cannot be

placed due to noise concerns,

agencies may consider a design

using an oscillating sine wave

pattern (also known as “mumble

strips”) that reduces noise outside

of the vehicle. However, the safety

benefits of this design need more

study.2

• Maintenance concerns:

• Where rumble strips are placed

along a pavement joint, there

are typically no issues with

joint stability if the pavement

structure and joint was already

in good condition.

• Studies have shown no

evidence of issues related to

snow, ice, or rain build-up in the

rumble strip.3

Shoulder rumble strips and center line rumble 

stripes are installed on this roadway. 

Source: FHWA 

Safety Benefits:

Center Line Rumble Strips

reduction in head-on fatal 

and injury crashes on 

two-lane rural roads.4

44-64%

Shoulder Rumble Strips

reduction in single vehicle, 

run-off-road fatal and 

injury crashes on two-lane 

rural roads.4

13-51%

Example of an edge line rumble stripe. 

Source: Missouri DOT

OFFICE OF SAFETY

Proven Safety 

Countermeasures

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter 

measures and https:// 

highways.dot.gov/safety/

rwd/keep-vehicles-road/ 

rumble-strips.
SafetyEdgeSM

The SafetyEdgeSM technology shapes the edge of the pavement at 

approximately 30 degrees from the pavement cross slope during the paving 

process. This safety practice eliminates the potential for vertical drop-off at 

the pavement edge, has minimal effect on project cost, and can improve 

pavement durability by reducing edge raveling of asphalt.

Rural road crashes involving edge 

drop-offs are 2-4 times more likely to 

include a fatality than other crashes 

on similar roads.1 Vehicles may leave 

the roadway for various reasons 

ranging from distracted driver errors 

to low visibility, or to the presence 

of an animal on the road. Exposed 

vertical pavement edges can cause 

vehicles to become unstable and 

prevent their safe return to the 

roadway. The SafetyEdgeSM gives 

drivers the opportunity to return to 

their travel lane while maintaining 

control of their vehicle. 

The SafetyEdgeSM technology only 

requires adding one of several 

commercially available devices to 

the screed or endgate when placing 

hot-mix asphalt. Forms for shaping 

the edge of concrete pavement are 

simpler and can be made on site 

by the contractor. Some agencies 

allow the SafetyEdgeSM to remain 

exposed while a segment is under 

construction, unlike conventional 

pavement edges. However, before 

construction ends, agencies should 

bring the adjacent roadside flush 

with the top of the pavement 

for both the SafetyEdgeSM and 

traditional pavement edge. Over 

time, regardless of the edge type, 

the edge may become exposed 

due to settling, erosion, and tire 

wear. When this occurs, the gentle 

slope provided by the SafetyEdgeSM

is preferred versus the traditional 

vertical pavement edge.

Transportation agencies should 

develop standards for implementing 

the SafetyEdgeSM systemwide on all 

new asphalt paving and resurfacing 

projects where curbs and/or 

guardrail are not present, while also 

encouraging standard application 

for concrete pavements.

FHWA-SA-21-038

Example of the SafetyEdgeSM after backfill 

material settles or erodes. Source: FHWA

Cross-section view of an overlay with the SafetyEdgeSM. Source: FHWA-SA-17-044 

11%

reduction in fatal and 

injury crashes.2

21%

reduction in 

run-off-road crashes.2

Safety Benefits:

19%

reduction in head-on 

crashes.2

Benefit-Cost Ratio Range3

700:1 to 1,500:1 $

1 Hallmark et al. Safety Impacts of Pavement Edge Drop-offs, (Washington, DC: 

AAA Foundation for Traffic Safety: 2006), p 93.

2 (CMF ID: 9205, 9211, 9217) Donnell et al. Development of Crash Modification Factors for 

the Application of the SafetyEdgeSM on Two-Lane Rural Roads. FHWA-HRT-17-081, (2017).

3 Safety Effects of the SafetyEdgeSM, FHWA-SA-17-044, (2017).

OFFICE OF SAFETY

Proven Safety 

Countermeasures

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter 

measures and https://high 

ways.dot.gov/safety/rwd/ 

provide-safe-recovery/ 

safetyedge.
FHWA-SA-21-029

Roadside Design 

Improvements at Curves

Horizontal curves account for 27 percent of all fatal crashes and 80 percent of 

all fatal crashes at curves are roadway departure crashes.1

 Roadside design 

improvements at curves is a strategy encompassing several treatments that 

target the high-risk roadside environment along the outside of horizontal curves. 

These treatments can reduce roadway departure fatalities and serious injuries 

by giving vehicles the opportunity to recover safely and by reducing crash 

severity.

Roadside design improvements can be implemented alone or in combination, 

and are particularly recommended at horizontal curves—where data indicates 

a higher risk for roadway departure fatalities and serious injuries.

Roadside Design Improvements to 

Provide for a Safe Recovery

In cases where a vehicle leaves 

the roadway, having strategic 

roadside design elements, including 

an added or widened shoulder, 

flattened sideslopes, or a widened 

clear zone can provide drivers with 

an opportunity to regain control and 

re-enter the roadway in their lane or 

come to a safe stop before rolling 

over or encountering a fixed object.

• A clear zone is an unobstructed,

traversable roadside area that

allows a driver to stop safely or

regain control of a vehicle that has

left the roadway. Agencies should

avoid adding new fixed objects

such as trees and utility cabinets or

poles in the clear zone. AASHTO’s

Roadside Design Guide details the

clear zone width adjustment factors

to be applied at horizontal curves.

• Slope flattening reduces the

steepness of the sideslope to

increase drivers’ ability to keep the

vehicle stable, regain control of the

vehicle, and avoid obstacles. Slopes

of 1V:4H or flatter are considered

recoverable (i.e., drivers can retain

control of a vehicle by slowing or

stopping). Slopes between 1V:3H

and 1V:4H are generally considered

traversable, but non-recoverable

(i.e., errant vehicle will continue to

the bottom of the slope).

• Adding or widening shoulders

gives drivers more recovery area

to regain control in the event of a

roadway departure.

Roadside Design Improvements to 

Reduce Crash Severity

Since not all roadside hazards can be 

removed, relocated, or redesigned 

at curves, installing roadside barriers 

to shield unmovable objects or steep 

embankments may be an appropriate 

treatment. Three common types of 

roadside barriers are:

• Cable barrier is a flexible barrier

made from steel cables mounted

on weak steel posts. Flexible barriers

are more forgiving and have the

most deflection.

• Metal-beam guardrail is a semirigid barrier where a W-beam or

box-beam is mounted on steel

or timber posts. These deflect less

than cable barriers, so they can

be located closer to objects where

space is limited.

• Concrete barrier is a rigid barrier

that has little to no deflection.

Clear zone provided on the outside of 

the curve. Source: FHWA.

8%

reduction for 

single-vehicle crashes.2

Flatten sideslope from 

1V:3H to 1V:4H: 

12%

reduction for 

single-vehicle crashes.2

Flatten sideslope from 

1V:4H to 1V:6H: 

Safety Benefits:

1 Fatality Analysis Reporting System.

2 (CMF ID: 4627,4632) NCHRP Report 617: Accident Modification Factors for 

Traffic Engineering and ITS Improvements, (2008).

3 (CMF ID: 35,36) Elvik, R., and Vaa, T. Handbook of Road Safety Measures, (2004). 

22%

reduction for all crashes.3

Increase the distance to 

roadside features from 

3.3 ft to 16.7 ft:

44%

reduction for all crashes.3

Increase the distance to 

roadside features from 

16.7 ft to 30 ft:

OFFICE OF SAFETY

Proven Safety 

Countermeasures

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter 

measures and https:// 

highways.dot.gov/safety/

rwd/provide-safe-recovery/

clear-zones/clear-zones.
Median Barriers

Median barriers are longitudinal barriers that separate opposing traffic on a 

divided highway and are designed to redirect vehicles striking either side of 

the barrier. Median barriers significantly reduce the number of cross-median 

crashes, which are attributed to the relatively high speeds that are typical 

on divided highways. AASHTO’s Roadside Design Guide (RDG) recommends 

guidelines for the use of median barriers on high-speed, fully controlledaccess roadways for locations where the median is 30 ft in width or less and 

the average daily traffic (ADT) is greater than 20,000 vehicles per day (vpd). 

For locations with median widths greater than 50 ft and where the ADT is less 

than 20,000 vpd, a median barrier is optional. For locations where the median 

is between 30 and 50 feet, the RDG suggests an analysis to determine the 

cost effectiveness of median barrier installation. Median barriers can be 

cable, metal-beam, or concrete.

• Cable barriers are flexible barriers,

made from steel cables mounted

on weak steel posts, resulting in

less occupant impact force as it

absorbs energy from the crash,

capturing or redirecting the

vehicle. Due to larger deflection,

median width is an important

consideration. These barriers are

more adaptable to slopes typically

found in medians. Cable barriers

tend to require more frequent

maintenance and repair than

other barrier types.

• Metal-beam guardrails are

considered semi-rigid barriers,

where the W-beam or box-beam

is mounted to steel or timber

posts. When impacted, they are

designed to deform and deflect,

absorbing some of the crash

energy and redirecting the vehicle.

Metal-beam guardrails often do

not require maintenance after

minor impacts. They deflect less

than cable barriers, so they can

be located closer to objects where

space is limited.

• Concrete barriers are usually rigid

and result in little to no deflection.

They redirect rather than absorb

energy from the impact. Rigid

concrete barriers seldom require

repair or maintenance. Some

agencies have used portable

concrete barriers as median

barriers. These barriers require

repositioning after an impact but 

are typically less maintenance than 

a post mounted barrier.

To reduce cross-median crashes, 

transportation agencies should 

review their head-on crash history 

on divided highways to identify hot 

spots. Agencies should also consider 

implementing a systemic approach 

to median barrier placement based 

on cross-median crash risk factors. 

Potential risk factors include:

• Traffic volumes.

• Vehicle classifications.

• Median crossover history.

• Crash incidents.

• Vertical and horizontal alignment.

• Median terrain configurations.

FHWA-SA-21-037

Median cable barrier prevents a 

potential head-on crash. 

Source: Washington State DOT

1 Fatality Analysis Reporting System.

2 (CMF ID: 7040) NCHRP Report 794: Median Cross-Section Design for 

Rural Divided Highways, (2011).

OFFICE OF SAFETY

Proven Safety 

Countermeasures

8%

of all fatalities on divided 

highways are due to 

head-on crashes.1

Safety Benefits:

Median Barriers Installed

on Rural Four-Lane

Freeways

97%

 reduction in 

cross-median crashes.

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter 

measures and https:// 

highways.dot.gov/safety/

rwd/reduce-crash-severity.

2
FHWA-SA-21-039

Backplates with 

Retroreflective Borders

Backplates added to a traffic signal head improve the visibility of the 

illuminated face of the signal by introducing a controlled-contrast 

background. The improved visibility of a signal head with a backplate 

is made even more conspicuous by framing it with a 1- to 3-inch yellow 

retroreflective border. Signal heads that have backplates equipped with 

retroreflective borders are more visible and conspicuous in both daytime 

and nighttime conditions.

This treatment is recognized as a 

human factors enhancement of 

traffic signal visibility, conspicuity, 

and orientation for both older 

and color vision deficient drivers. 

This countermeasure is also 

advantageous during periods of 

power outages when the signals 

would otherwise be dark, providing a 

visible cue for motorists to stop at the 

intersection ahead.

Considerations

Transportation agencies should 

consider backplates with 

retroreflective borders as part 

of their efforts to systematically 

improve safety performance at 

signalized intersections. Adding a 

retroreflective border to an existing 

signal backplate is a very low-cost 

safety treatment. This can be done 

by either adding retroreflective 

tape to an existing backplate or 

purchasing a new backplate with 

a retroreflective border already 

incorporated. The most efficient 

means of implementing this proven 

safety countermeasure is to adopt 

it as a standard treatment for 

signalized intersections across a 

jurisdiction or State.

Implementation challenges 

include minimizing installation time, 

accessing existing signal heads, and 

structural limitations due to added 

wind load in instances where an 

entire backplate is added. Agencies 

should consider the design of the 

existing signal support structure to 

determine if the design is sufficient to 

support the added wind load.

15%

reduction in total crashes.1

Safety Benefits:

Retroreflective Border

Signal Backplate

Signal backplate framed with a 

retroreflective border. Source: FHWA

Retroreflective borders are highly 

visible during the night. Source: South 

Carolina DOT

1 (CMF ID: 1410) Sayed, T., Leur, P., and Pump, J., “Safety Impact of Increased Traffic Signal 

Backboards Conspicuity.” 2005 TRB 84th Annual Meeting: Compendium of 

Papers CD-ROM, Vol. TRB#05-16, Washington, D.C., (2005).

OFFICE OF SAFETY

Proven Safety 

Countermeasures

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter 

measures and https://rosap.

ntl.bts.gov/view/dot/42807.
Corridor Access 

Management

Access management refers to the design, application, and control of 

entry and exit points along a roadway. This includes intersections with other 

roads and driveways that serve adjacent properties. Thoughtful access 

management along a corridor can simultaneously enhance safety for all 

modes, facilitate walking and biking, and reduce trip delay and congestion. 

Every intersection, from a signalized 

intersection to an unpaved driveway, 

has the potential for conflicts 

between vehicles, pedestrians, and 

bicyclists. The number and types of 

conflict points—locations where the 

travel paths of two users intersect—

influence the safety performance of 

the intersection or driveway. FHWA 

developed corridor-level crash 

prediction models to estimate and 

analyze the safety effects of selected 

access management techniques 

for different area types, land uses, 

roadway variables, and traffic 

volumes.1

The following access management 

strategies can be used individually or 

in combination with one another:

• Reduce density through driveway

closure, consolidation, or

relocation.

• Manage spacing of intersection

and access points.

• Limit allowable movements at

driveways (such as right-in/

right-out only).

• Place driveways on an intersection

approach corner rather than a

receiving corner, which is expected

to have fewer total crashes.2

• Implement raised medians

that preclude across-roadway

movements.

• Utilize designs such as roundabouts

or reduced left-turn conflicts

(such as restricted crossing U-turn,

median U-turns, etc.).

• Provide turn lanes (i.e., left-only,

right-only, or interior two-way left).

• Use lower speed one-way or twoway off-arterial circulation roads.

Successful corridor access 

management involves balancing 

overall safety and mobility for 

all users along with the needs of 

adjacent land uses.

FHWA-SA-21-040

5-23%

reduction in total crashes 

along 2-lane rural roads.3

25-31%

reduction in fatal and 

injury crashes along urban/

suburban arterials.4

Schematic of an intersection and adjacent access points. Source: FHWA

Tandem roundabouts with a continuous raised 

median eliminates left-turn and across-roadway 

conflicts. Source: FHWA

Safety Benefits:

Reducing driveway density

1 Gross et al. Safety Evaluation of Access Management 

Policies and Techniques. FHWA-HRT-14-057, (2018).

2 Le et al. Safety Evaluation of Corner Clearance at 

Signalized Intersections. FHWA-HRT-17-084, (2018). 

3 Harwood et al. Prediction of the Expected Safety Performance of 

Rural Two-Lane Highways. FHWA-RD-99-207, (2000).

4 (CMF ID: 179,178) Elvik, R. and Vaa, T., Handbook of Road Safety Measures. 

Oxford, United Kingdom, Elsevier, (2004).

OFFICE OF SAFETY

Proven Safety 

Countermeasures

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter 

measures and https://high 

ways.dot.gov/safety/ 

intersection-safety/cam.
Dedicated Left- and 

Right-Turn Lanes at Intersections

Auxiliary turn lanes—either for left turns or right turns—provide physical 

separation between turning traffic that is slowing or stopped and adjacent 

through traffic at approaches to intersections. Turn lanes can be designed to 

provide for deceleration prior to a turn, as well as for storage of vehicles that 

are stopped and waiting for the opportunity to complete a turn.

While turn lanes provide measurable 

safety and operational benefits at 

many types of intersections, they 

are particularly helpful at two-way 

stop-controlled intersections. Crashes 

occurring at these intersections are 

often related to turning maneuvers. 

Since the major route traffic is free 

flowing and typically travels at higher 

speeds, crashes that do occur are 

often severe. The main crash types 

include collisions of vehicles turning 

left across opposing through traffic 

and rear-end collisions of vehicles 

turning left or right with other vehicles 

following closely behind. Turn lanes 

reduce the potential for these types 

of crashes.

Installing left-turn lanes and/or rightturn lanes should be considered 

for the major road approaches 

for improving safety at both threeand four-leg intersections with stop 

control on the minor road, where 

significant turning volumes exist, 

or where there is a history of turnrelated crashes. Pedestrian and 

bicyclist safety and convenience 

should also be considered when 

adding turn lanes at an intersection. 

Specifically, offset left- and right-turn 

lanes will lengthen crossing distances 

for pedestrians.

Offset Turn Lanes

Providing offset of left- and rightturn lanes to increase visibility can 

provide added safety benefits, and 

is preferable in many situations, 

particularly at locations with higher 

speeds, or where free-flow or 

permissive movements are possible. 

At turn lanes with zero or negative 

offset, turning vehicles can block 

sightlines. For left-turn lanes, this 

usually involves opposing left-turning 

vehicles occupying the turn lanes 

at the same time. For right-turn 

lanes, this typically involves rightturning vehicles from the major 

road and vehicles entering the 

intersection from the minor road. 

In both scenarios, adding positive 

offset to turn lanes enhances the 

sight distance to approaching 

vehicles that conflict with the turning 

movement. Offset turn lanes should 

be considered when there is a high 

frequency of these types of conflicts 

in order to reduce the likelihood of a 

severe crash.

FHWA-SA-21-041

Illustration comparing zero offset to positive offset of left- and right-turn lanes. Source: FHWA

Left-Turn Lanes

reduction in total crashes.1

28-48%

Right-Turn Lanes

reduction in total crashes.1

14-26%

Safety Benefits:

Positive Offset 

Left-Turn Lanes

reduction in fatal 

and injury crashes.2

36% 

Zero Offset Positive Offset

1 (CMF ID: 260, 268, 285, 289) Harwood et al. Safety Effectiveness of Intersection 

Left- and Right-Turn Lanes. FHWA-HRD-02-089, (2002).

2 (CMF ID: 6096) Persaud et al. Safety Evaluation of Offset Improvements 

for Left-Turn Lanes. FHWA-HRT-09-035, (2009).

OFFICE OF SAFETY

Proven Safety 

Countermeasures

 Left- and right-turn lanes at a two-way 

stop-controlled intersection. Source: City 

of Greeley, CO 

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/safety/

proven-safety-countermeasures 

and https://www.fhwa.dot.gov/ 

publications/research/safety 

/02103/02103techbrief.pdf.
FHWA-SA-21-030

Reduced Left-Turn 

Conflict Intersections

Reduced left-turn conflict intersections are geometric designs that alter how 

left-turn movements occur. These intersections simplify decision-making for 

drivers and minimize the potential for higher severity crash types, such as 

head-on and angle. Two highly effective designs that rely on U-turns to 

complete certain left-turn movements are known as the Restricted Crossing 

U-turn (RCUT) and the Median U-turn (MUT).

Restricted Crossing U-turn 

The RCUT intersection, also known 

as a J-Turn, Superstreet, or Reduced 

Conflict Intersection, modifies 

the direct left-turn and through 

movements from cross-street 

approaches. Minor road traffic makes 

a right turn followed by a U-turn at a 

designated location—either signalized 

or unsignalized—to continue in 

the desired direction. The RCUT is 

suitable for and adaptable to a wide 

variety of circumstances, ranging 

from isolated rural, high-speed 

locations to urban and suburban 

high-volume, multimodal corridors. 

It is a competitive and less costly 

alternative to constructing an 

interchange. RCUTs work well 

when consistently used along 

a corridor, but also can be 

used effectively at individual 

intersections. Studies have 

shown that installing an RCUT 

can result in a 30-percent 

increase in throughput and a 

40-percent reduction in network

intersection travel time.1 

Median U-turn 

The MUT intersection modifies 

direct left turns from the major 

approaches. Vehicles proceed 

through the main intersection, 

make a U-turn a short distance 

downstream, followed by a right 

turn at the main intersection. 

The U-turns can also be used for 

modifying the cross-street left turns, 

similar to the RCUT.

The MUT is an excellent choice for 

intersections with heavy through 

traffic and moderate left-turn 

volumes. Studies have shown a 

20- to 50-percent improvement in

intersection throughput for various

lane configurations as a result of

implementing the MUT design. When

implemented at multiple intersections

along a corridor, the efficient twophase signal operation of the MUT

can reduce delay, improve travel

times, and create more crossing

opportunities for pedestrians and

bicyclists.

Example of a MUT intersection. Source: FHWA 

Safety Benefits:

RCUT

Two-Way 

Stop-Controlled to RCUT: 

54%

reduction in fatal 

and injury crashes.2 

Signalized Intersection 

to Signalized RCUT: 

22%

reduction in fatal 

and injury crashes.3 

Unsignalized Intersection 

to Unsignalized RCUT: 

63%

reduction in fatal and 

injury crashes. 4

MUT

30%

reduction in intersectionrelated injury crash rate.5

Example of a unsignalized RCUT intersection. 

Source: FHWA 

3

1 2

1 Hugher and Jagannathan. Restricted Crossing U-Turn Intersection. FHWA-HRT-09-059, (2009). 

2 (CMF ID: 5556) Edara et al. Evaluation of J-turn Intersection Design Performance in Missouri. MoDOT, (2013).

3 (CMF ID: 9985) Hummer and Rao. Safety Evaluation of a Signalized Restricted Crossing U-Turn. 

FHWA-HRT-17-082, (2017).

4 (CMF ID: 4884) Hummer et al. Superstreet Benefits and Capacities. FHWA/NC/2009-06, 

NC State University, (2010).

5 (CMF ID: 10867) Synthesis of the Median U-Turn Treatment, Safety, and Operational Benefits, 

FHWA-HRT-07-033, (2007).

OFFICE OF SAFETY

Proven Safety 

Countermeasures

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/safety/

proven-safety-countermeasures 

and https://highways.dot. 

gov/safety/intersectionsafety/intersection-types/ 

reduced-left-turn-conflictintersections.
FHWA-SA-21-042

Roundabouts

The modern roundabout is an intersection with a circular configuration that 

safely and efficiently moves traffic. Roundabouts feature channelized, curved 

approaches that reduce vehicle speed, entry yield control that gives right-ofway to circulating traffic, and counterclockwise flow around a central island 

that minimizes conflict points. The net result of lower speeds and reduced 

conflicts at roundabouts is an environment where crashes that cause injury or 

fatality are substantially reduced. 

Roundabouts are not only a safer 

type of intersection; they are also 

efficient in terms of keeping people 

moving. Even while calming traffic, 

they can reduce delay and queuing 

when compared to other intersection 

alternatives. Furthermore, the lower 

vehicular speeds and reduced 

conflict environment can create 

a more suitable environment for 

walking and bicycling.

Roundabouts can be implemented 

in both urban and rural areas under 

a wide range of traffic conditions. 

They can replace signals, twoway stop controls, and all-way 

stop controls. Roundabouts are an 

effective option for managing speed 

and transitioning traffic from highspeed to low-speed environments, 

such as freeway interchange ramp 

terminals, and rural intersections 

along high-speed roads. 

Example of a single-lane roundabout. Source: FHWA

Illustration of a multilane roundabout. 

Source: FHWA 

Two-Way Stop-Controlled 

Intersection to a Roundabout

82%

reduction in fatal 

and injury crashes.1

Signalized Intersection to a 

Roundabout

78%

reduction in fatal 

and injury crashes.1

Safety Benefits:

1 (CMF ID: 211,226) AASHTO. The Highway Safety Manual, American Association 

of State Highway Transportation Professionals, Washington, D.C., (2010).

OFFICE OF SAFETY

Proven Safety 

Countermeasures

78%

reduction in fatal 

and injury crashes.1

For more information on this 

and other FHWA Proven 

Safety Countermeasures, 

please visit https://highways.

dot.gov/safety/provensafety-countermeasures and 

https://highways.dot.gov/ 

safety/intersection-safety/ 

intersection-types/roundabouts.
Systemic Application 

of Multiple Low-Cost Countermeasures 

at Stop-Controlled Intersections

This systemic approach to intersection safety involves deploying a package 

of multiple low-cost countermeasures, including enhanced signing and 

pavement markings, at a large number of stop-controlled intersections 

within a jurisdiction. These countermeasures increase driver awareness and 

recognition of the intersections and potential conflicts. 

There are several benefits to 

systemically applying multiple 

low-cost countermeasures at stopcontrolled intersections, including,

• Resources are maximized because

the treatments are low cost.

• A high number of intersections can

receive treatment.

• Improvements are highly costeffective, with an average benefitcost ratio of 12:1, even assuming a

conservative 3-year service life.

The low-cost countermeasures 

for stop-controlled intersections 

generally consist of the following 

treatments:

On the Through Approach

• Doubled-up (left and right),

oversized advance intersection

warning signs, with supplemental

street name plaques (can also

include flashing beacon).

• Retroreflective sheeting on sign

posts.

• Enhanced pavement markings that

delineate through lane edge lines.

On the Stop Approach

• Doubled-up (left and right),

oversized advance “Stop Ahead”

intersection warning signs (can also

include flashing beacon).

• Doubled-up (left and right),

oversized Stop signs.

• Retroreflective sheeting on sign

posts.

• Properly placed stop bar.

• Removal of vegetation, parking,

or obstructions that limit sight

distance.

• Double arrow warning sign at stem

of T-intersections.

FHWA-SA-21-031

Example of countermeasures 

on the stop approach. 

Source: South Carolina DOT

10%

15%

reduction of nighttime 

crashes at all locations/

types/areas.

reduction of fatal and 

injury crashes at all 

locations/types/areas.

Average 

Benefit-Cost Ratio

12:1 $

27%

19%

reduction of fatal and injury 

crashes at 2-lane by 2-lane 

intersections.

reduction of fatal and 

injury crashes at rural 

intersections.

Safety Benefits:

Example of countermeasures on the 

through approach. 

Source: South Carolina DOT

Source: (CMF ID: 8867, 8870, 8874, 8893) T. Le et al. “Safety Effects of Low-Cost Systemic 

Safety Improvements at Signalized and Stop-Controlled Intersections,” 96th Annual 

Meeting of the Transportation Research Board, Paper Number 17-05379, January 2017.

OFFICE OF SAFETY

Proven Safety 

Countermeasures

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/ 

safety/proven-safety-counter 

measures and https://highways.

dot.gov/sites/fhwa.dot.gov/

files/2022-06/fhwasa18047.pdf.
FHWA-SA-21-043

Yellow Change 

Intervals

At a signalized intersection, the yellow change interval is the length of 

time that the yellow signal indication is displayed following a green signal 

indication. The yellow signal confirms to motorists that the green has ended 

and that a red will soon follow.

Since red-light running is a leading 

cause of severe crashes at signalized 

intersections, it is imperative that 

the yellow change interval be 

appropriately timed. Too brief an 

interval may result in drivers being 

unable to stop safely and cause 

unintentional red-light running. 

Too long of an interval may result 

in drivers treating the yellow as 

an extension of the green phase 

and invite intentional red-light 

running. Factors such as the speed 

of approaching and turning 

vehicles, driver perception-reaction 

time, vehicle deceleration, and 

intersection geometry should all be 

considered in the timing calculation.

Transportation agencies can improve 

signalized intersection safety and 

reduce red-light running by reviewing 

and updating their traffic signal 

timing policies and procedures 

concerning the yellow change 

interval. Agencies should institute 

regular evaluation and adjustment 

protocols for existing traffic signal 

timing. Refer to the Manual on 

Uniform Traffic Control Devices for 

basic requirements and further 

recommendations about yellow 

change interval timing.1

 As part of 

strategic signal system modernization 

and updates, incorporating 

automated traffic signal 

performance measures (ATSPMs) is 

a proven approach to improve on 

traditional retiming processes. ATSPMs 

provide continuous performance 

monitoring capability and the ability 

to modify timing based on actual 

performance, without requiring 

expensive modeling or data 

collection.2

8-14%

reduction in 

total crashes.3

12%

reduction in 

injury crashes.3

Appropriately timed yellow change intervals 

can reduce red-light running and improve 

overall intersection safety. Source: FHWA 

Safety Benefits:

36-50%

reduction in 

red light running.3

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter

measures and https://high 

ways.dot.gov/sites/fhwa.dot.

gov/files/2022-06/ 

fhwasa13027.pdf.

1 Manual on Uniform Traffic Control Devices (MUTCD), Section 4F.17. FHWA, (2023).

2 Federal Highway Administration. “Automated Traffic Signal Performance,” (2020). 

3 (CMF ID: 380,384) NCHRP Report 731: Guidelines for Timing Yellow and All-Red Intervals 

at Signalized Intersections, (2011).

OFFICE OF SAFETY

Proven Safety 

Countermeasures
FHWA-SA-21-049

Crosswalk Visibility 

Enhancements

Poor lighting conditions, obstructions such as parked cars, and horizontal or 

vertical roadway curvature can reduce visibility at crosswalks, contributing 

to safety issues. For multilane roadway crossings where vehicle volumes are 

in excess of 10,000 Average Annual Daily Traffic (AADT), a marked crosswalk 

alone is typically not sufficient. Under such conditions, more substantial 

crossing improvements could prevent an increase in pedestrian crash 

potential. 

Three main crosswalk visibility enhancements help make crosswalks and the 

pedestrians, bicyclists, wheelchair and other mobility device users, and transit 

users using them more visible to drivers. These include high-visibility crosswalks, 

lighting, and signing and pavement markings. These enhancements can also 

assist users in deciding where to cross. Agencies can implement these features 

as standalone or combination enhancements to indicate the preferred 

location for users to cross. 

High-visibility crosswalks

High-visibility crosswalks use patterns 

(i.e., bar pairs, continental, ladder) 

that are visible to both the driver 

and pedestrian from farther 

away compared to traditional 

transverse line crosswalks. They 

should be considered at all 

midblock pedestrian crossings and 

uncontrolled intersections. Agencies 

should use materials such as inlay or 

thermoplastic tape, instead of paint 

or brick, for highly reflective crosswalk 

markings.

Improved Lighting

The goal of crosswalk lighting 

should be to illuminate with positive 

contrast to make it easier for a driver 

to visually identify the pedestrian. 

This involves carefully placing the 

luminaires in forward locations to 

avoid a silhouette effect of the 

pedestrian. 

Enhanced Signing and 

Pavement Markings

On multilane roadways, agencies 

can use “YIELD Here to Pedestrians” 

or “STOP Here for Pedestrians” 

signs 20 to 50 feet in advance of 

a marked crosswalk to indicate 

where a driver should stop or yield to 

pedestrians, depending on State law. 

To supplement the signing, agencies 

can also install a STOP or YIELD bar 

(commonly referred to as “shark’s 

teeth“) pavement markings. 

In-street signing, such as “STOP Here 

for Pedestrians” or “YIELD Here to 

Pedestrians” may be appropriate on 

roads with two- or three-lane roads 

where speed limits are 30 miles per 

hour or less. 

40%1

High-visibility crosswalks 

can reduce pedestrian injury 

crashes up to:

25%3

Advance yield or stop 

markings and signs can 

reduce pedestrian 

crashes up to:

42%2

Intersection lighting can 

reduce pedestrian crashes 

up to:

1 (CMF ID: 4123) Chen, L., C. Chen, and R. Ewing. The Relative Effectiveness of Pedestrian 

Safety Countermeasures at Urban Intersections - Lessons from a New York City Experience. (2012). 

2 (CMF ID: 436) Elvik, R. and Vaa, T. Handbook of Road Safety Measures. Oxford, United 

Kingdom, Elsevier, (2004).

3 (CMF ID: 9017) Zeeger et al. Development of Crash Modification Factors for Uncontrolled 

Pedestrian Crossing Treatments, FHWA, (2017). 

Source: FHWA

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter

measures and https://high 

ways.dot.gov/sites/fhwa.dot.

gov/files/2022-06/techSheet_

VizEnhancemt2018.pdf.

Safety Benefits:

Transportation agencies should refer to the Manual on Uniform Traffic Control Devices 

(MUTCD) for information on crosswalk markings (Chapter 3C) and in-street signing 

(Sections 2B.19 and 2B.20).

OFFICE OF SAFETY

Proven Safety 

Countermeasures
Bicycle lane in Washington, DC. 

Source: Alex Baca, Washington Area 

Bicyclist Association.

FHWA-SA-21-051

Bicycle Lanes

Most fatal and serious injury bicyclist crashes occur at non-intersection locations. 

Nearly one-third of these crashes occur when motorists are overtaking bicyclists1

because the speed and size differential between vehicles and bicycles can lead 

to severe injury. Many people are not comfortable riding a bicycle because of 

their fear that this type of crash may occur. To make bicycling safer and more 

comfortable for most types of bicyclists, State and local agencies should consider 

installing bicycle lanes. Providing bicycle facilities can mitigate or prevent 

interactions, conflicts, and crashes between bicyclists and motor vehicles, and 

create a network of safer roadways for bicycling. Bicycle Lanes align with the 

Safe System Approach principle of recognizing human vulnerability—where 

separating users in space can enhance safety for all road users.

Applications

The FHWA’s Bikeway Selection Guide

and Incorporating On-Road Bicycle 

Networks into Resurfacing Projects

assist agencies in determining which 

facilities provide the most benefit in 

various contexts. Bicycle lanes can be 

included on new roadways or created 

on existing roads by reallocating 

space in the right-of-way through 

Road Diets. Separated bicycle lanes, 

which use vertical elements—such 

as flexible delineator posts, curbs, or 

vegetation—between the bicycle 

lane and motorized traffic lanes 

provide additional safety benefits.2,3

For a marked bike lane without vertical 

elements, a lateral offset with marked 

buffer can help to further separate 

bicyclists from vehicle traffic. 

Considerations 

• In order to maximize a roadway’s

suitability for riders of all ages

and abilities, bicycle lane design

should vary according to roadway

characteristics (number of lanes,

motor vehicle and truck volumes,

speed, presence of transit), user needs

(current and forecasted ridership,

types of bicycles and micromobility

devices in use within the community,

role within the bicycling network), and

land-use context (adjacent land uses,

types and intensity of conflicting uses,

demands from other users for curbside

access). Separated bicycle lanes are

recommended on roadways with

higher vehicle volumes and speeds,

such as arterials.

• City and State policies may require

minimum bicycle lane widths,

although desirable bicycle lane widths

can differ by agency and functional 

classification of the road, current 

and forecasted bicycle volumes, 

and contextual attributes such as 

topography.

• Studies have found that roadways did

not experience an increase in crashes

or congestion when travel lane widths

were decreased to add a bicycle

lane.4

• Studies and experience in U.S. cities

show that bicycle lanes increase

ridership and may help jurisdictions

better manage roadway capacity.

• In rural areas, rumble strips can

negatively impact bicyclists’ ability to

ride if not properly installed. Agencies

should consider the dimensions,

placement, and offset of rumble strips

when adding a bicycle lane.5

• Bicycle lanes should be considered on

roadways where adjacent land use

suggests that trips could be served by

varied modes, particularly to meet the

safety and travel needs of low-income

populations likely to use bicycles to

reach essential destinations.6

49%

for total crashes on urban 

4-lane undivided collectors

and local roads.7

Bicycle Lane Additions can 

reduce crashes up to:

30%

for total crashes on urban 

2-lane undivided collectors

and local roads.7

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/ 

safety/proven-safety-counter 

measures and https://high 

ways.dot.gov/sites/fhwa.dot.

gov/files/2022-07/ 

fhwasa18077.pdf.

Safety Benefits:

1 Thomas et al. Bicyclist Crash Types on National, 

State, and Local Levels: A New Look. Transportation 

Research Record 673(6), 664-676, (2019). 

2 Separated Bike Lane Planning and Design Guide. 

FHWA-HEP-15-025, (2015).

3 (CMF ID: 11296) Developing CMFs for Separated 

Bicycle Lanes. FHWA-HRT-23-025, (2023).

4 Park and Abdel-Aty. Evaluation of safety 

effectiveness of multiple cross sectional features on 

urban arterials. Accident Analysis and Prevention, 

Vol. 92, pp. 245-255, (2016).

5 FHWA Tech Advisory Shoulder and Edge Line Rumble 

Strips, (2011).

6 Sandt et al. Pursuing Equity in Pedestrian and Bicycle 

Planning. FHWA, (2016).

7 (CMF ID: 10738, 10742) Development of Crash 

Modification Factors for Bicycle Lane Additions While 

Reducing Lane and Shoulder Widths. 

FHWA-HRT-21-012, (2021).

53%

for bicycle/vehicle crashes.3

Converting traditional or flush 

buffered bicycle lanes to a 

separated bicycle lane with 

flexible delineator posts can 

reduce crashes up to:

OFFICE OF SAFETY

Proven Safety 

Countermeasures
47%

 for pedestrian crashes.4

98%

(varies by speed limit, number 

of lanes, crossing distance, 

and time of day).3

FHWA-SA-21-053

Rectangular Rapid 

Flashing Beacons (RRFB) 

A marked crosswalk or pedestrian warning sign can improve safety for 

pedestrians crossing the road, but at times may not be sufficient for drivers 

to visibly locate crossing locations and yield to pedestrians. To enhance 

pedestrian conspicuity and increase driver awareness at uncontrolled, 

marked crosswalks, transportation agencies can install a pedestrian 

actuated Rectangular Rapid Flashing Beacon (RRFB) to accompany a 

pedestrian warning sign. RRFBs consist of two, rectangular- shaped yellow 

indications, each with a light-emitting diode (LED)-array-based light source.1

RRFBs flash with an alternating high frequency when activated to enhance 

conspicuity of pedestrians at the crossing to drivers. 

Transportation agencies should refer to the Manual on Uniform Traffic Control 

Devices (MUTCD) for information on the application of RRFBs.1

 

1 Manual on Uniform Traffic Control Devices (MUTCD), Chapter 4L. FHWA, (2023).

2 “Rectangular Rapid Flash Beacon” in PEDSAFE: Pedestrian Safety Guide 

and Countermeasure Selection System. FHWA, (2013). 

3 Fitzpatrick et al. “Will You Stop for Me? Roadway Design and Traffic Control 

Device Influences on Drivers Yielding to Pedestrians in a Crosswalk with a 

Rectangular Rapid-Flashing Beacon.” Report No. TTI-CTS-0010. Texas A&M 

Transportation Institute, (2016).

4 (CMF ID: 9024) NCHRP Research Report 841 Development of Crash Modification 

Factors for Uncontrolled Pedestrian Crossing Treatments, (2017). 

Applications

The RRFB is applicable to many 

types of pedestrian crossings but is 

particularly effective at multilane 

crossings with speed limits less 

than 40 miles per hour.2

 Research 

suggests RRFBs can result in motorist 

yielding rates as high at 98 percent 

at marked crosswalks, but varies 

depending on the location, posted 

speed limit, pedestrian crossing 

distance, one- versus two-way road, 

and the number of travel lanes.3

RRFBs can also accompany school or 

trail crossing warning signs. 

RRFBs are placed on both sides of 

a crosswalk below the pedestrian 

crossing sign and above the 

diagonal downward arrow plaque 

pointing at the crossing.1

 The flashing 

pattern can be activated with 

pushbuttons or passive (e.g., video or 

infrared) pedestrian detection, and 

should be unlit when not activated.

Considerations

Agencies should:2

• Install RRFBs in the median rather

than the far-side of the roadway

if there is a pedestrian refuge or

other type of median.

• Use solar-power panels to eliminate

the need for a power source.

• Reserve the use of RRFBs for

locations with significant pedestrian

safety issues, as over-use of RRFB

treatments may diminish their

effectiveness.

Agencies shall not:2

• Use RRFBs without the presence of

a pedestrian, school or trail crossing

warning sign.

• Use RRFBs for crosswalks across

approaches controlled by YIELD

signs, STOP signs, traffic control

signals, or pedestrian hybrid

beacons, except for the approach

or egress from a roundabout.

RRFBs used at a trail crossing. 

Source: LJB

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/ 

safety/proven-safety-counter

measures and https://high 

ways.dot.gov/sites/fhwa.dot.

gov/files/2022-06/techSheet_

RRFB_2018.pdf. 

Safety Benefits:

RRFBs can reduce 

crashes up to:

RRFBs can increase motorist 

yielding rates up to:

OFFICE OF SAFETY

Proven Safety 

Countermeasures
FHWA-SA-21-032

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/ 

safety/proven-safety-counter

measures and https://highways.

dot.gov/sites/fhwa.dot.gov/

files/2022-06/fhwasa19040.pdf.

Leading Pedestrian 

Interval

A leading pedestrian interval (LPI) gives pedestrians the opportunity to 

enter the crosswalk at an intersection 3-7 seconds before vehicles are given 

a green indication. Pedestrians can better establish their presence in the 

crosswalk before vehicles have priority to turn right or left. 

LPIs provide the following benefits:

• Increased visibility of crossing

pedestrians.

• Reduced conflicts between

pedestrians and vehicles.

• Increased likelihood of motorists

yielding to pedestrians.

• Enhanced safety for pedestrians

who may be slower to start into the

intersection.

FHWA’s Handbook for Designing 

Roadways for the Aging Population

recommends the use of the LPI at 

intersections with high turning vehicle 

volumes. Transportation agencies 

should refer to the Manual on Uniform 

Traffic Control Devices for guidance on 

LPI timing and ensure that pedestrian 

signals are accessible for all users.1

Costs for implementing LPIs are very 

low when only signal timing alteration 

is required.

13%

reduction in pedestrianvehicle crashes at 

intersections.2

LPIs reduce potential conflicts between 

pedestrians and turning vehicles. 

Source: FHWA

Safety Benefits:

An LPI allows a pedestrian to establish a 

presence in the crosswalk before vehicles are 

given a green indication. Source: FHWA

1 Manual on Uniform Traffic Control Devices (MUTCD), Section 4I.06. FHWA, (2023).

2 (CMF ID: 9918) Goughnour, E., D. Carter, C. Lyon, B. Persaud, B. Lan, P. Chun, I. Hamilton, 

and K. Signor. “Safety Evaluation of Protected Left-Turn Phasing and Leading Pedestrian 

Intervals on Pedestrian Safety.” Report No. FHWA-HRT-18-044. Federal Highway 

Administration. (October 2018)

OFFICE OF SAFETY

Proven Safety 

Countermeasures
Pedestrian Refuge 

Island

reduction in 

pedestrian crashes.2

Median with 

Marked Crosswalk

reduction in 

pedestrian crashes.2

FHWA-SA-21-044

Medians and 

Pedestrian Refuge Islands in Urban 

and Suburban Areas 

A median is the area between opposing lanes of traffic, excluding turn 

lanes. Medians in urban and suburban areas can be defined by pavement 

markings, raised medians, or islands to separate motorized and nonmotorized road users.

A pedestrian refuge island (or crossing area) is a median with a refuge area 

that is intended to help protect pedestrians who are crossing a road.

1 National Center for Statistics and Analysis. (2020, March). Pedestrians: 

2018 data (Traffic Safety Facts. Report No. DOT HS 812 850). National Highway 

Traffic Safety Administration

2 (CMF ID: 175) Desktop Reference for Crash Reduction Factors, FHWA-SA-08-011, 

September 2008, Table 11. 

Pedestrian crashes account for 

approximately 17 percent of all traffic 

fatalities annually, and 74 percent 

of these occur at non-intersection 

locations.1

 For pedestrians to 

safely cross a roadway, they must 

estimate vehicle speeds, determine 

acceptable gaps in traffic based 

on their walking speed, and predict 

vehicle paths. Installing a median 

or pedestrian refuge island can 

help improve safety by allowing 

pedestrians to cross one direction of 

traffic at a time.

Transportation agencies should 

consider medians or pedestrian 

refuge islands in curbed sections of 

urban and suburban multilane 

roadways, particularly in areas with 

a significant mix of pedestrian and 

vehicle traffic, traffic volumes over 

9,000 vehicles per day, and travel 

speeds 35 mph or greater. Medians/

refuge islands should be at least 

4-ft wide, but preferably 8 ft for

pedestrian comfort. Some example

locations that may benefit from

medians or pedestrian refuge islands

include:

• Mid-block crossings.

• Approaches to multilane

intersections.

• Areas near transit stops or other

pedestrian-focused sites.

Example of a road with a median and 

pedestrian refuge islands. 

Source: City of Charlotte, NC

Median and pedestrian refuge island 

near a roundabout. Source: 

www.pedbikeimages.org / Dan Burden 

46%

56% 

Safety Benefits:

OFFICE OF SAFETY

Proven Safety 

Countermeasures

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter 

measures and https://high 

ways.dot.gov/sites/fhwa.dot.

gov/files/2022-08/techSheet_

PedRefugeIsland2018.pdf.
FHWA-SA-21-045

Pedestrian Hybrid 

Beacons

The pedestrian hybrid beacon (PHB) is a traffic control device designed to 

help pedestrians safely cross higher-speed roadways at midblock crossings 

and uncontrolled intersections. The beacon head consists of two red lenses 

above a single yellow lens. The lenses remain “dark” until a pedestrian desiring 

to cross the street pushes the call button to activate the beacon, which then 

initiates a yellow to red lighting sequence consisting of flashing and steady 

lights that directs motorists to slow and come to a stop, and provides the rightof-way to the pedestrian to safely cross the roadway before going dark again.

1 National Center for Statistics and Analysis. (2020, March). Pedestrians: 

2018 data (Traffic Safety Facts. Report No. DOT HS 812 850). National 

Highway Traffic Safety Administration

2 Manual on Uniform Traffic Control Devices, Chapter 4J. FHWA, (2023).

3 (CMF ID: 9020) Zegeer et al. NCHRP Report 841: Development of Crash Modification 

Factors for Uncontrolled Pedestrian Crossing Treatments. TRB, (2017).

4 (CMF ID: 2911,2917) Fitzpatrick, K. and Park, E.S. Safety Effectiveness of the 

HAWK Pedestrian Crossing Treatment, FHWA-HRT-10-042, (2010).

Nearly 74 percent of pedestrian 

fatalities occur at non-intersection 

locations, and vehicle speeds are 

often a major contributing factor.1

As a safety strategy to address this 

pedestrian crash risk, the PHB is an 

intermediate option between a 

flashing beacon and a full pedestrian 

signal because it assigns right of way 

and provides positive stop control. It 

also allows motorists to proceed once 

the pedestrian has cleared their side 

of the travel lane(s), reducing vehicle 

delay.

Transportation agencies should refer 

to the Manual on Uniform Traffic Control 

Devices (MUTCD) for information 

on the application of PHBs.2

Transportation agencies should locate 

pedestrian signals to be accessible for 

all users.

In general, PHBs are used where it 

is difficult for pedestrians to cross 

a roadway, such as when gaps in 

traffic are not sufficient or speed 

limits exceed 35 miles per hour. 

They are very effective at locations 

where three or more lanes will 

be crossed or traffic volumes are 

above 9,000 annual average daily 

traffic. Installation of a PHB must 

also include a marked crosswalk 

and pedestrian countdown signal. 

If PHBs are not already familiar to a 

community, agencies should conduct 

appropriate education and outreach 

as part of implementation. Example of PHBs mounted 

on a mast arm. Source: FHWA

Sequence for a PHB. Source: MUTCD 2023 Edition, Chapter 4J, FHWA

29%

reduction in total crashes.4

15% 

reduction in fatal and 

serious injury crashes.4

55%

reduction in 

pedestrian crashes.3

Safety Benefits:

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/ 

safety/proven-safety-counter

measures and https://high 

ways.dot.gov/sites/fhwa.dot.

gov/files/2022-06/ 

fhwasa18064.pdf.

OFFICE OF SAFETY

Proven Safety 

Countermeasures
FHWA-SA-21-046

Road Diets 

(Roadway Reconfiguration)

A Road Diet, or roadway reconfiguration, can improve safety, calm traffic, 

provide better mobility and access for all road users, and enhance overall 

quality of life. A Road Diet typically involves converting an existing four-lane 

undivided roadway to a three-lane roadway consisting of two through lanes 

and a center two-way left-turn lane (TWLTL).

Benefits of Road Diet installations 

may include:

• Reduction of rear-end and left-turn

crashes due to the dedicated

left-turn lane.

• Reduced right-angle crashes as

side street motorists cross three

versus four travel lanes.

• Fewer lanes for pedestrians to

cross.

• Opportunity to install pedestrian

refuge islands, bicycle lanes,

on-street parking, or transit stops.

• Traffic calming and more consistent

speeds.

• A more community-focused,

Complete Streets environment that

better accommodates the needs

of all road users.

A Road Diet can be a low-cost 

safety solution when planned in 

conjunction with a simple pavement 

overlay, and the reconfiguration can 

be accomplished at no additional 

cost. Typically, a Road Diet is 

implemented on a roadway with 

a current and future average daily 

traffic of 25,000 or less.

19-47%

reduction in total crashes.1

Road Diet project in Honolulu, Hawaii. 

Source: Leidos

Road Diet Conversions

Safety Benefits:

4-Lane to 3-Lane

BEFORE AFTER

Before and after example of a Road Diet. Source: FHWA

1 (CMF ID: 5554,2841) Evaluation of Lane Reduction “Road Diet” Measures on Crashes, 

FHWA-HRT-10-053, (2010).

OFFICE OF SAFETY

Proven Safety 

Countermeasures

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter 

measures and https:// 

highways.dot.gov/safety/ 

other/road-diets.
FHWA-SA-21-047

Walkways

A walkway is any type of defined space or pathway for use by a person 

traveling by foot or using a wheelchair. These may be pedestrian walkways, 

shared use paths, sidewalks, or roadway shoulders. 

With more than 6,200 pedestrian 

fatalities and 75,000 pedestrian 

injuries occurring in roadway 

crashes annually,1 it is important for 

transportation agencies to improve 

conditions and safety for pedestrians 

and to integrate walkways more 

fully into the transportation system. 

Research shows people living in lowincome communities are less likely 

to encounter walkways and other 

pedestrian-friendly features.2

Well-designed pedestrian walkways, 

shared use paths, and sidewalks 

improve the safety and mobility of 

pedestrians. Pedestrians should have 

direct and connected network of 

walking routes to desired destinations 

without gaps or abrupt changes. In 

some rural or suburban areas, where 

these types of walkways are not 

feasible, roadway shoulders provide 

an area for pedestrians to walk next 

to the roadway, although these are 

not preferable.

Transportation agencies should work 

towards incorporating pedestrian 

facilities into all roadway projects 

unless exceptional circumstances 

exist. It is important to provide and 

maintain accessible walkways along 

both sides of the road in urban areas, 

particularly near school zones and 

transit locations, and where there is a 

large amount of pedestrian activity. 

Walkable shoulders should also be 

considered along both sides of rural 

highways when routinely used by 

pedestrians.

Example of a sidewalk in a residential area. 

Source: pedbikeimages.org / Burden 

 Paved shoulder used as a walkway. Source: pedbikeimages.org / Burden 

Safety Benefits:

Sidewalks

reduction in crashes involving 

pedestrians walking along 

roadways.3

65-89%

Paved Shoulders

reduction in crashes involving 

pedestrians walking along 

roadways.3

71%

1 National Center for Statistics and Analysis. (2020, March). Pedestrians: 

2018 data (Traffic Safety Facts. Report No. DOT HS 812 850). National 

Highway Traffic Safety Administration.

2 Gibbs, et all. Income Disparities in Street Features that Encourage Walking. 

Bridging the Gap, (2012, March).

3 Gan et al. Update of Florida Crash Reduction Factors and Countermeasures 

to Improve the Development of District Safety Improvement Projects. Florida DOT, (2005).

OFFICE OF SAFETY

Proven Safety 

Countermeasures

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter 

measures and http://www.

pedbikesafe.org/PEDSAFE/

countermeasures_detail.

cfm?CM_NUM=1.
Pavement Friction 

Management

Friction is a critical characteristic of a pavement that affects how vehicles 

interact with the roadway, including the frequency of crashes. Measuring, 

monitoring, and maintaining pavement friction—especially at locations 

where vehicles are frequently turning, slowing, and stopping—can prevent 

many roadway departure, intersection, and pedestrian-related crashes.

Pavement friction treatments, such as High Friction Surface Treatment (HFST), 

can be better targeted and result in more efficient and effective installations 

when using continuous pavement friction data along with crash and roadway 

data. 

Continuous Pavement Friction 

Measurement

Friction data for safety performance 

is best measured with Continuous 

Pavement Friction Measurement 

(CPFM) equipment. Spot friction 

measurement devices, like lockedwheel skid trailers, cannot safely and 

accurately collect friction data in 

curves or intersections, where the 

pavement polishes more quickly and 

adequate friction is so much more 

critical. Without CPFM equipment, 

agencies will assume the same 

friction over a mile or more. 

CPFM technology measures friction 

continuously at highway speeds and 

provides both network and segment 

level data. Practitioners can analyze 

the friction, crash, and roadway data 

to better understand and predict 

where friction-related crashes will 

occur to better target locations and 

more effectively install treatments.1

High Friction Surface Treatment

HFST consists of a layer of durable, 

anti-abrasion, and polish-resistant 

aggregate over a thermosetting 

polymer resin binder that locks the 

aggregate in place to restore or 

enhance friction and skid resistance. 

Calcined bauxite is the aggregate 

shown to yield the best results 

and should be used with HFST 

applications. 

Applications

HFST should be applied in locations 

with increased friction demand, 

including: 

• Horizontal curves.

• Interchange ramps.

• Intersection approaches.

o Higher-speed signalized and

stop-controlled intersections.

o Steep downward grades.

• Locations with a history of rear-end,

failure to yield, wet-weather, or redlight-running crashes.

• Crosswalk approaches.

Considerations

• HFST is applied on existing pavement,

so no new pavement is added.

• If the underlying pavement

structure is unstable, then the

HFST life cycle may be shortened,

resulting in pre-mature failure.

• The automated installation method

is preferred as it minimizes issues

often associated with manual

installation: human error due to

fatigue, inadequate binder mixing,

improper and uneven binder

thickness, delayed aggregate

placement, and inadequate

aggregate coverage.

• The cost can be reduced when

bundling installations at multiple

locations.

FHWA-SA-21-052

Automated application of HFST. 

Source: FHWA

HFST can reduce 

crashes up to:

for injury crashes at ramps.2

63%

for injury crashes at 

horizontal curves.2

48%

for total crashes at 

intersections.3

20%

Safety Benefits:

1 Izeppi et al. Continuous Friction Measurement Equipment as a Tool for Improving Crash 

Rate Prediction: A Pilot Study. Virginia Department of Transportation, (2016).

2 (CMF ID: 10342,10333) Merritt et al. Development of Crash Modification Factors 

for High Friction Surface Treatments. FHWA, (2020). 

3 (CMF ID: 2259) NCHRP Report 617: Accident Modification Factors for Traffic 

Engineering and ITS Improvements, (2008).

OFFICE OF SAFETY

Proven Safety 

Countermeasures

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/ 

safety/proven-safety-counter 

measures and https:// 

highways.dot.gov/safety/

rwd/keep-vehicles-road/

pavement-friction/hfst.
 1 (CMF ID: 436,433,192) Elvik, R. and Vaa, T., “Handbook of 

Road Safety Measures.” Oxford, United Kingdom, Elsevier, (2004).

2 (CMF ID: 2376) Ye et al. A Simultaneous Equations Model of Crash Frequency 

By Collision Type for Rural Intersections, 87th Annual Meeting of the Transportation 

Research Board, (2008). FHWA-SA-21-050

Lighting

The number of fatal crashes occurring in daylight is about the same as those 

that occur in darkness. However, the nighttime fatality rate is three times the 

daytime rate because only 25 percent of vehicle miles traveled (VMT) occur at 

night. At nighttime, vehicles traveling at higher speeds may not have the ability 

to stop once a hazard or change in the road ahead becomes visible by the 

headlights. Therefore, lighting can be applied continuously along segments 

and at spot locations such as intersections and pedestrian crossings in order to 

reduce the chances of a crash. 

Adequate lighting (i.e., at or above minimum acceptable standards) is based 

on research recommending horizontal and vertical illuminance levels to 

provide safety benefits to all users of the roadway environment. Adequate 

lighting can also provide benefits in terms of personal security for pedestrians, 

wheelchair and other mobility device users, bicyclists, and transit users as they 

travel along and across roadways. 

Applications

Roadway Segments 

Research indicates that continuous 

lighting on both rural and urban 

highways (including freeways) has 

an established safety benefit for 

motorized vehicles.1

 Agencies can 

provide adequate visibility of the 

roadway and its users through the 

uniform application of lighting that 

provides full coverage along the 

roadway and the strategic placement 

of lighting where it is needed the most. 

Intersections and Pedestrian 

Crossings 

Increased visibility at intersections at 

nighttime is important since various 

modes of travel cross paths at these 

locations. Agencies should consider 

providing lighting to intersections 

based on factors such as a history of 

crashes at nighttime, traffic volume, 

the volume of non-motorized users, 

the presence of crosswalks and raised 

medians, and the presence of transit 

stops and boarding volumes.

Considerations

Most new lighting installations are 

made with breakaway features, 

shielded, or placed far enough 

from the roadway to reduce 

the probability and/or severity 

of fixed-object crashes. Modern 

lighting technology gives precise 

control with minimal excessive 

light affecting the nighttime sky or 

spilling over to adjacent properties. 

Agencies can equitably engage 

with underserved communities to 

determine where and how new and 

improved lighting can most benefit 

the community by considering their 

priorities, including eliminating crash 

disparities, connecting to essential 

neighborhood services, improving 

active transportation routes, and 

promoting personal safety. 

Source: FHWA

28%

for nighttime injury crashes 

on rural and urban 

highways.1

42%

for nighttime injury pedestrian 

crashes at intersections.1

33-38%

for nighttime crashes at rural 

and urban intersections.2,1

Source: FHWA

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/ 

safety/proven-safety-counter

measures and https:// 

highways.dot.gov/safety/

other/visibility/roadwaylighting-resources.

Safety Benefits:

Lighting can reduce 

crashes up to:

OFFICE OF SAFETY

Proven Safety 

Countermeasures
FHWA-SA-21-033

Local Road 

Safety Plans

A local road safety plan (LRSP) provides a framework for identifying, 

analyzing, and prioritizing roadway safety improvements on local roads. 

The LRSP development process and content are tailored to local issues 

and needs. The process results in a prioritized list of issues, risks, actions, and 

improvements that can be used to reduce fatalities and serious injuries on 

local roads. FHWA has developed several resources including an LRSP DoIt-Yourself website which further explains the process and includes resources 

local agencies and their partners need to create and implement an LRSP.1

1 https://highways.dot.gov/safety/local-rural/local-road-safety-plans

2 Anderson et al. Noteworthy Practices: Addressing Safety on Locally-Owned 

and Maintained Roads A Domestic Scan, FHWA-SA-09-019, (2010). 

3 Developing Safety Plans: A Manual for Local Rural Road Owners, FHWA-SA-12-017, 

provides guidance on developing an LRSP. 

Approximately 75 percent of rural 

roads are owned by local agencies.2 

While local roads are less traveled 

than State highways, they have a 

much higher rate of fatal and serious 

injury crashes.2 Developing an LRSP is 

an effective strategy to improve 

local road safety for all road users 

and support the goals of a State’s 

overall Strategic Highway Safety Plan 

(SHSP).

Although the development process 

and resulting plan can vary 

depending on the local agency’s 

needs, available resources, and 

targeted crash types, aspects 

common to LRSPs include:

• Stakeholder engagement

representing the 4E’s:

engineering,

enforcement,

education, and

emergency

medical services.

• Collaboration

among

municipal,

county, Tribal,

State, and/or

Federal entities

to leverage

expertise and

resources.

• Identification of target crash types

and crash risk with corresponding

recommended proven safety

countermeasures.

• Timeline and goals for

implementation and evaluation.

Local road agencies should consider 

developing an LRSP to be used as a 

tool for reducing roadway fatalities, 

injuries, and crashes.3

 LRSPs can 

help agencies create a prioritized 

list of improvements. LRSPs are 

also a proactive risk management 

technique to demonstrate an 

agency’s responsiveness. The 

plan should be viewed as a living 

document that can be updated to 

reflect changing local needs and 

priorities.

Infographic showing the LRSP process. Source: FHWA

Safety Benefits:

OFFICE OF SAFETY

Proven Safety 

Countermeasures

Agencies have experienced 

the following benefits after 

LRSP implementation:

25%

reduction in county road 

fatalities in Minnesota.

17%

reduction in fatal and 

serious injury crashes on 

county-owned roads in 

Washington State. 

35%

reduction in severe 

curve crashes in Thurston 

County, WA.

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/ 

safety/proven-safety-counter 

measures and https:// 

highways.dot.gov/safety/ 

local-rural/local-roadsafety-plans.
FHWA-SA-21-048

Road Safety Audit

While most transportation agencies have established traditional safety 

review procedures, a road safety audit (RSA) or assessment is unique. RSAs 

are performed by a multidisciplinary team independent of the project. RSAs 

consider all road users, account for human factors and road user capabilities, 

are documented in a formal report, and require a formal response from the 

road owner. (See the eight steps for conducting an RSA below.)

RSAs provide the following 

benefits:

• Reduced number and severity of

crashes due to safer designs.

• Reduced costs resulting from early

identification and mitigation of

safety issues before projects are

built.

• Increased opportunities to

integrate multimodal safety

strategies and proven safety

countermeasures.

• Expanded ability to consider

human factors in all facets of

design.

• Increased communication and

collaboration among safety

stakeholders.

• Objective review by independent

multidisciplinary team.

RSAs can be performed in any 

phase of project development, 

from planning through construction. 

Agencies may focus RSAs 

specifically on motorized vehicles, 

pedestrians, bicyclists, motorcyclists, 

or a combination of these roadway 

users. Agencies are encouraged 

to conduct an RSA at the earliest 

stage possible, as all roadway design 

options and alternatives are being 

explored.

Multidisciplinary team performs field review 

during an RSA. Source: FHWA

10-60%

reduction in total crashes.1

Source: FHWA 

Safety Benefits:

1 Road Safety Audits: An Evaluation of RSA Programs and Projects, 

FHWA-SA-12-037; and FHWA Road Safety Audit Guidelines, FHWA-SA-06-06.

OFFICE OF SAFETY

Proven Safety 

Countermeasures

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter 

measures and https:// 

highways.dot.gov/safety/

data-analysis-tools/systemic/

road-safety-audits-rsa.
FHWA-SA-21-071

https://highways.dot.gov/safety/proven-safety-countermeasures