Practical Safety 

Solutions for Local 

and Tribal Roads: 

A Human Factors Approach

August 20, 2020

http://safety.fhwa.dot.gov

FHWA-SA-20-071
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

i 

Notice 

This document is disseminated under the sponsorship of the U.S. 

Department of Transportation in the interest of information 

exchange. The U.S. Government assumes no liability for the use of 

the information contained in this document. 

The U.S. Government does not endorse products or manufacturers. 

Trademarks or manufacturers’ names appear in this report only 

because they are considered essential to the objective of the 

document.
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

ii

Quality Assurance Statement 

The Federal Highway Administration (FHWA) provides high-quality 

information to serve Government, industry, and the public in a 

manner that promotes public understanding. Standards and policies 

are used to ensure and maximize the quality, objectivity, utility, and 

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Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

iii

Technical Documentation Page

1. Report No.

HWA-SA-20-071

2. Government 

Accession No.

3. Recipient's 

Catalog No.

4. Title and Subtitle

Practical Safety Solutions for Local and 

Tribal Roads: A Human Factors Approach

5. Report Date

August 2020

6. Performing 

Organization Code

7.Author(s) 

Paula Raymond, Rosemarie Anderson, 

Kayla Sykes

8. Performing 

Organization Report 

No.

9. Performing Organization Name and 

Address

Vanasse Hangen Brustlin, Inc (VHB)

940 Main Campus Drive 

Raleigh, NC 27606

Toxcel, LLC

7140 Heritage Village Plaza 

Gainesville, Virginia 20155

10. Work Unit No.

11. Contract or 

Grant No.

DTFH61-16-D00052

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

Guide, July 23, 

2020 – October 29, 

2020

14. Sponsoring 

Agency Code

FHWA

15. Supplementary Notes

FHWA Technical Project Manager: Rosemarie Anderson, Office 

of Safety

Technical Oversight Working Group: Kelly Morton, FHWA; Greg 

Morris, FHWA, Adam Larsen, FHWA; Kathleen Davis, 

Washington DOT; David Orr, New York LTAP; Lawrence 

Hummel, Hubbel, Roth & Clark, Inc.; Mark Borst, Sedgwick 

County, KS

16. Abstract

Human factors principles explain how road users gather 

information, make sense of that information, make decisions, and 

execute actions when traveling on the roadways. Understanding 

these principles can assist in identifying safety issues and 
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

iv

selecting the most effective countermeasures to address those 

issues on local and tribal roads. Using plain language, this report 

provides the practitioner with information on the effects of road 

users actions on roadway safety and how, when, and where to 

use this information to improve safety on their roadways. The 

information provided is not a substitute but a complement to 

technical information found in other documents. Throughout the 

report references are provided.

17. Key Words: 

Human factors, safety, road 

users, local roads, tribal roads

18. Distribution Statement

No restrictions.

19. Security 

Classif. (of 

this report)

Unclassified

20. Security 

Classif. (of 

this page) 

Unclassified

21. No. of 

Pages

68

22. Price
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

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Glossary

The definitions in this glossary are written in plain language. 

Further technical information is available in the text, 

references, and at www.fhwa.dot.gov.

Advisory Speed: a speed below the speed limit that is 

recommended for a section of highway. The advisory speed is 

normally determined through an engineering study that considers 

highway design, operating characteristics, and conditions.

Alignment: The path or direction a roadway takes.

Center line: Pavement marking that marks the separation between 

opposing streams of traffic. 

Changeable Message Sign: An electronic traffic sign used to give 

road users information. 

Clear Zone: An unobstructed roadside area that allows road users 

to stop safely or regain control of a vehicle that has left the roadway. 

Clearing obstructions can assist road users in their view of the road 

ahead and can minimize the consequences of roadway departure. 

The width of the clear zone should be based on risk (also called 

exposure). Key factors in assessing risk include traffic volumes, 

speeds, and slopes.

Crown: The part of the roadway shape in which the center of the 

road is higher than the outer edges. 

Design Consistency: Conformance of a highway’s geometric and 

operational features with driver expectancy. 

Design Speed: The speed selected for the roadway during the 

design process. Designers consider the shape and use of the 

surrounding land, the expected operating speed and types of 

vehicles, and the type of roadway needed. They use this information 

to determine the characteristics of the roadway to be built.

Edge Line: The line that marks the edge of the road. 

Gateway: A combination of traffic control treatments that mark the 

entrance to a town or village. 

Guide Signs: Signs that direct road users along streets and 

highways and inform them of important destinations. 

GLOSSARY
Practical Safety Solutions for Local and Tribal Roads: 

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High Friction Surface Treatment (HFST): Pavement treatments 

that dramatically and immediately reduce crashes, injuries, and 

fatalities associated with friction demand issues, such as wet 

pavement, excessive vehicle speed, or roadway 

geometry/curvature. 

Horizontal Pavement Markings: Simple regulatory, advisory, or 

guidance information that is applied to the roadway as a pavement 

marking to supplement one or more signs. Sometimes called 

"horizontal signing."

Operating Speed: When vehicles are in freeflow (undisturbed by 

traffic control devices or heavy traffic) the operating speed is usually 

defined as the 85th percentile of the observed vehicles speeds. That 

is, 85% of vehicles are traveling at this speed or slower, and 15% 

are traveling faster than this speed. Operating speed is a measure 

of actual use, and it may not be the same as the design speed.

Perception-Reaction Time: The amount of time a road user needs

to perceive and understand information, make a decision, and 

execute the response.

Posted Speed: The highest lawful speed vehicles can travel. 

Regulatory Signs: Signs that inform road users of traffic laws or 

regulations. 

Retroreflective Materials: Sign and marking materials that reflect 

light straight back to the source. These materials look bright when 

headlights hit them. Retroreflective materials are conspicuous at 

night or under low-light conditions. 

Road Diet: Reducing the number or width of through travel lanes to 

provide space for bike lanes, sidewalks, and/or medians. 

Roadway Departure: When a single vehicle leaves the road or 

crosses the center line. 

Rumble Strips, Longitudinal: A series of milled or raised elements 

on or near the center or edge line of a paved roadway. These alert 

road users (through vibration and sound) that their vehicles have left 

the travel lane.

Rumble Strips, Transverse: A series of milled or raised strips 

across the roadway that act as a warning to road users when 

approaching a curve or intersection.

GLOSSARY
Practical Safety Solutions for Local and Tribal Roads: 

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SafetyEdgeSM: A pavement edge consolidated at approximately 30-

degrees while paving to prevent vertical pavement edge drop-off. 

This allows drivers who drift off the roadway to safely re-enter. 

Self-Enforcing Road: Road users make inferences about speed 

selection and expected maneuvers based on physical 

characteristics of the roadway. A self-enforcing road has 

characteristics that lead users to select appropriate speeds.

Shared Use Path: A path separated from a roadway that can be 

used by cyclists, pedestrians, and other non-motorized users. 

Sight Distance: The distance at which a driver can see objects in 

the roadway before their line of vision is blocked. 

Sign Complexity: The amount of information provided and how 

hard it may be to process it.

Skewed Intersection: Optimally, an intersection should be 

designed to have roadways cross at a 90-degree angle. In situations 

where the intersecting angles are 60 degrees or less, the 

intersections are considered skewed.

Transition Zone: The section of roadway before a motorist enters a 

community, where drivers need to identify an upcoming change in 

roadway character and reduce travel speed in preparation for 

entering the community. 

Warning Sign: Gives road users advance indication of a hazard 

ahead on the roadway. 

GLOSSARY
Practical Safety Solutions for Local and Tribal Roads: 

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viii

Table of Contents

Glossary........................................................................................... v

Introduction ..................................................................................... 1

The Guide...................................................................................... 1

Guide Elements............................................................................. 3

Human Factors Principles.............................................................. 6

Information Overload..................................................................... 7

Positive Guidance ......................................................................... 9

User Expectancy .........................................................................11

Priority of Information Needs.......................................................13

Distraction ...................................................................................15

Visual Perception at Night ...........................................................17

Safety Challenges .........................................................................19

Unsignalized Intersections ..........................................................20

Signs ...........................................................................................23

Pavement Markings.....................................................................26

Roadway Departure on Straight Sections........................................28

Roadway Departure on Curves.......................................................30

Speeding ......................................................................................33

School Zones and School Crossings...............................................36

Pedestrian Safety ..........................................................................39

Bicyclist Safety ..............................................................................42

Work Zone Safety..........................................................................45

Unpaved Roads ............................................................................47

Cross-Reference Table................................................................. 51

References.....................................................................................53

TABLE OF CONTENTS
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

1 

Introduction

An understanding of basic human factors principles can be useful 

when identifying and addressing local and tribal road safety 

challenges. Human factors principles explain how road users gather 

information, make sense of that information, make decisions, and 

execute actions. This understanding can assist in selecting the most 

effective countermeasures for safety challenges. 

This guide assists road practitioners in understanding road user 

capabilities and limitations. Practitioners can then use that 

understanding to improve safety. This guide is not a replacement for 

other design references and standards such as the Manual on 

Uniform Traffic Control Devices (MUTCD), the Highway Safety 

Manual, or any other guidance. It is a complement to them – another 

tool to use in the pursuit of enhanced safety. 

The Guide 

The purpose of this guide is to provide information on how road user 

actions affect road safety and how to apply this information. This 

document defines and describes some useful human factors 

principles and supplies information about using the principles to 

improve safety. 

This guide offers six basic human factors principles that can be 

useful to practitioners. 

• Information Overload: When road users are overwhelmed 

with information, they make errors. When there is too much 

information, road users may not have time to locate the 

most critical information, make sense of it, make decisions, 

and respond appropriately. 

• Positive Guidance: Road users need information about 

the road ahead so they can prepare the correct maneuvers. 

They need accurate information, placed in the correct 

location, in a form they can understand easily.

• User Expectancy: Road users make assumptions about 

the road ahead. When these expectancies are violated, 

users’ planned responses will be incorrect, and they may 

not have time to evaluate the roadway and change their 

responses quickly enough.

INTRODUCTION
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

2 

• Priority of Information Needs: Information that is 

necessary for basic vehicle control is more urgent than 

guidance (for example, choosing the correct lane); 

guidance is more urgent than wayfinding information. When 

offering information to road users, consider which level of 

information they need.

• Distraction: When road users’ attention is diverted from 

their primary task, they miss important information about 

the roadway and other road users. 

• Visual Perception at Night: Nighttime limits the timing, 

quality, and location of information road users can acquire 

and use for safe travel. 

These principles can help practitioners identify issues and select 

potential solutions. The guide then gives eleven common Safety 

Challenges, as follows:

• Unsignalized Intersections

• Signs

• Pavement Markings

• Roadway Departure on Straight Sections

• Roadway Departure on Curves

• Speeding

• School Zone and School Crossings

• Pedestrian Safety

• Bicyclist Safety

• Work Zone Safety

• Unpaved Roads 

Each safety challenge includes an explanation of how human 

factors principles relate to that challenge; how they help 

practitioners to anticipate and mitigate human error; and how to use 

the principles to select effective, practical solutions. Each topic 

offers other online and print resources and defines technical terms 

that are often used when discussing that topic. 

The Office of Safety maintains a web site with information that local 

and tribal practitioners will find useful. This web site covers a variety 

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

INTRODUCTION
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

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Guide Elements

Human factors principles help us understand and predict road user 

actions. The most basic principles that help with road safety are 

those that explain how road users get information, make decisions, 

and execute actions on the road. Each principle describes the way 

human capabilities and limitations affect road safety.

The tabs on the side of each page represent the guide element. 

Each element is examined in the following format:

• Guide Element Title 

• WHY is this important?

• WHEN and WHERE is this useful? 

• WHAT can we do to improve safety? 

• An illustration or photo

• Useful Terms for Further Reading

• Cross-references in this book 

• Useful Links

GUIDE ELEMENTS
Practical Safety Solutions for Local and Tribal Roads: 

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GUIDE ELEMENTS
Practical Safety Solutions for Local and Tribal Roads: 

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Practical Safety Solutions for Local and Tribal Roads: 

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Six basic Human Factors Principles 

are described in the following sections:

Information Overload

Positive Guidance

User Expectancy

Priority of Information Needs

Distraction

Visual Perception at Night

Human Factors Principles

HUMAN FACTORS PRINCIPLES
Practical Safety Solutions for Local and Tribal Roads: 

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Information Overload is a function of the quantity of information 

offered and the time available for its processing. When the quantity of 

information is too great for the time allowed, road users can experience 

Information Overload and make errors in comprehension, decisionmaking, and execution.

There is a limit to the amount of information that a person can process 

in a short time. When a road user tries to take in too much information 

in too little time, they may miss information, misunderstand it, or they 

may be confused. They may make incorrect decisions and unsafe 

maneuvers.

Road users must constantly make decisions as they navigate the 

roadway. Presenting too much information in the same location can lead 

to overload resulting in: 

• Confusion 

• Slowing or stopping in traffic 

• Leaving travel lane 

• Failure to notice other road users 

• Failure to read and understand road signs 

Recognize that road users must keep most of their attention on the task.

• Signs should be simple so that they are quickly read and understood. 

• Space signs apart to give road users time to read and respond while 

driving. When possible, avoid placing signs in areas with background 

clutter. 

• Minimize demands on attention in places where users must make 

decisions or where vehicle control is more demanding, like curves or 

merge points. Try to place wayfinding information on road sections 

where the driving task may need less attention.

WHAT can we do to improve safety?

WHEN and WHERE is this useful?

WHY is this important?

Information Overload | Human Factors Principle

HUMAN FACTORS PRINCIPLES: INFORMATION OVERLOAD
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

8 

When too much information is presented in too little time, road users 

may miss important cues in the environment. 

©2010 James Group Studio Inc. 

Information Overload is sometimes discussed as an issue of workload. 

When a person has to do several things under time pressure, their 

workload is high, and they may be unable to devote their attention to a 

single task. 

The amount of time a road user needs to perceive and understand 

information, make a decision, and execute the response is called 

perception-reaction time. Be sure to allow for perception-reaction time

when placing signs and other information upstream from decision points.

Distraction, Positive Guidance, Signs, Priority of Information Needs, 

Roadway Departure, Work Zones

NCHRP Report 600, “Human Factors Guidelines for Road Systems” has 

more information in Chapter 3, “Finding Information Like a Road User:” 

http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_600second.pdf 

The Manual on Uniform Traffic Control Devices (MUTCD) gives specific 

guidance on Signs, their placement, and needed perception-reaction 

time in: https://mutcd.fhwa.dot.gov/htm/2009/part2/part2_toc.htm

Useful Links

Cross-References in this Book

Useful Terms for Further Reading

HUMAN FACTORS PRINCIPLES: INFORMATION OVERLOAD
Practical Safety Solutions for Local and Tribal Roads: 

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Signs, markings, and advisory speeds provide a good view of the road 

ahead to give users the information they need to safely negotiate the 

road. 

Tell road users what to expect. Whenever possible, give road users 

appropriate information so they can prepare for the correct maneuvers.

• Remove visual obstructions as much as you can. 

• Use signs, pavement markings, advisory speed signs, and warning 

signs to give road users information about the road ahead. 

• Provide delineations on guardrails and chevrons at curves when

warranted.

• Use countermeasures consistently.

WHAT can we do to improve safety?

Positive Guidance offers information about roadway characteristics 

to help road users make safe maneuvers.

The principle of Positive Guidance can help in choosing the right 

information for road users at the right time. Giving road users accurate 

information is critical for safety.

When a roadway feature takes drivers by surprise, safety can suffer. 

Unexpected curves or crests, intersections, lane drops, or other features 

are often associated with crashes. Offering road users the appropriate 

roadway information and indicating the safe maneuver speed can help 

prevent these crashes.

WHEN and WHERE is this useful?

WHY is this important?

Positive Guidance | Human Factors Principle

HUMAN FACTORS PRINCIPLES: POSITIVE GUIDANCE
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

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When road users can look at the road and know what to expect regarding 

speed, traffic volume, and the way that vehicles get on and off the road, 

that is a self-enforcing road. A self-enforcing road uses the road itself to 

encourage road users to naturally adopt proper behavior consistent with 

road design and function. Positive Guidance can target a specific area 

and give users the information they need to safely negotiate the roadway.

The clear zone is an unobstructed roadside area that allows road users 

to stop safely or regain control of a vehicle that has left the roadway. 

Clearing obstructions can assist road users in their view of the road 

ahead and can minimize the consequences of roadway departure. The 

width of the clear zone should be based on risk (also called exposure). 

Key factors in assessing risk include traffic volumes, speeds, and slopes.

Priority of Information Needs, Work Zones, Roadway Departure on 

Curves, Speeding

A simple method to evaluate low-volume roads incorporating the 

principles of driver expectancy and Positive Guidance: 

https://rosap.ntl.bts.gov/view/dot/40402

Useful Links

Cross-References in this Book

Useful Terms for Further Reading

A curve warning sign gives road users accurate information about the 

roadway ahead. ©2018 ODOT.

HUMAN FACTORS PRINCIPLES: POSITIVE GUIDANCE
Practical Safety Solutions for Local and Tribal Roads: 

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• Use warning signs and pavement markings to accurately convey 

upcoming road features. It is important to give users information about 

the road ahead. 

• Provide backplate for signal heads at strategic locations.

• Use signs and pavement markings consistently. Users should be able 

to rely on information (such as the presence of a warning sign) to 

mean the same thing in different places.

User Expectancies are assumptions that road users make about 

the road ahead based on experience or habit. When expectancies are not 

met, users are more likely to make errors.

User Expectancies affect the way that road users take in information, 

interpret it, and make decisions. Accurate expectancies are helpful to 

road users. However, violated expectancies lead to longer reaction times, 

confusion, and errors.

A road user has expectations about the road ahead based on their 

experience and what they currently see. Expectancies affect the accuracy 

and speed of user responses (perception-reaction time).

When the user’s expectancy is not met, their performance suffers, and 

they may make unsafe maneuvers that can result in a crash. This tends to 

be a problem for drivers more than for bicyclists or pedestrians because 

of the speed of travel but can be an issue for any road user.

Expectancies can be unmet in a number of ways including the following:

• When the road type or features suddenly change (for example, a series 

of moderate curves that is followed by a very sharp curve).

• Unusual or uncommon features like a left exit, skewed intersection, or 

change in road surface (such as paved road to Unpaved Road).

• Unusual environmental features, such as fog or sun glare.

• Features or practices that are new – a change in speed limit, lane shift, 

new signal, work zone, or recent change can be especially jarring for 

familiar users who have long-standing expectancies.

WHEN and WHERE is this useful?

WHY is this important?

User Expectancy | Human Factors Principle

WHAT can we do to improve safety?

HUMAN FACTORS PRINCIPLES: USER EXPECTANCY
Practical Safety Solutions for Local and Tribal Roads: 

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User expectancies can be leveraged to improve safety when those 

expectancies give people the correct preparation for the road ahead. A 

self-explaining road conveys proper expectations to road users in terms 

of the correct speed, amount of traffic, and the ways that vehicles enter 

and exit the road. Self-explaining roads and User Expectancy are

strongly related because self-explaining roads use those expectancies to 

influence behavior. 

The amount of time a road user needs to perceive and understand 

information, make a decision, and execute the response. is called 

perception-reaction time.

Priority of Information Needs, Positive Guidance, Work Zones, 

Roadway Departure on Curves, Speeding

A step-by-step guide to analyzing a site for expectancy violations can 

be found here: https://rosap.ntl.bts.gov/view/dot/890

User expectancies and the self-explaining road concept have been 

investigated the most thoroughly for the potential to decrease 

Speeding. Guidance on self-explaining roads and speed management 

can be found here: 

https://www.fhwa.dot.gov/publications/research/safety/17098/17098.pdf

Useful Links

Cross-References in this Book

Useful Terms for Further Reading

In this work zone, the warning sign shows a lane shift to the left. 

Road users' expectancies may be violated when the road shifts to the 

right instead. Source: FHWA

HUMAN FACTORS PRINCIPLES: USER EXPECTANCY
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

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Road users constantly seek out information. They require different kinds 

of information for driving and navigation at different times. Considering 

these needs can help determine which kind of information should be 

offered and, as a result, where it should be placed. Information that is 

necessary for basic vehicle control must be prioritized over guidance such 

as lane choice, and guidance information must take priority over 

wayfinding.

It is important to give road users the type of information they need at the 

right time for them to safely negotiate the roadway. Road users must 

control the vehicle with steering, acceleration, and deceleration; they must 

choose the travel speed and lane; and they must navigate the route to 

their destination. These fall into three levels of vehicle operation: low-level 

basic vehicle control (steering), medium-level guidance (curve or 

intersection ahead), and high-level navigation (wayfinding). These tasks 

all require different information at different places and times.

Operators of any vehicle need information for three levels of vehicle 

operation. 

For low-level basic vehicle control, road users need information about 

road characteristics that will tell them how to steer and accelerate or 

brake.

For medium-level driving decisions, drivers need information about traffic 

and road conditions that will help them choose a lane, maintain following 

distance, and make other responses that keep them on the correct path. 

For high-level navigation, drivers need information that will help them get 

to their correct destination. 

Road users watch for all kinds of information, but when lower-level vehicle 

control needs are intense, they cannot take in higher-level information. 

For example, users need information about the road characteristics that is 

necessary for vehicle control when navigating a sharp curve. At that 

moment, information about the curve is more important than knowing a 

lane change might be necessary in the next two miles (a medium-level 

need); or knowing the name of the next cross street (a high-level 

navigation need.)

WHEN and WHERE is this useful?

WHY is this important?

Priority of Information Needs | Human Factors Principle

HUMAN FACTORS PRINCIPLES: PRIORITY OF INFORMATION NEEDS
Practical Safety Solutions for Local and Tribal Roads: 

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14

• Recognize that information for low-level vehicle control must take 

priority over higher-level information. 

• Recognize that road users have limitations on the amount of 

information they can take in at one time.

• Give advance warning of hazards with warning signs and advisory 

speeds.

• Offer higher-level information (like wayfinding information) at times 

when lower level tasks are simple. This allows users to take in the 

wayfinding information before executing a more demanding maneuver.

WHAT can we do to improve safety?

The Priority of Information Needs is also called the hierarchy of 

information needs. 

When we talk about how mentally busy a person is, we call it workload. 

When a road user must do several things in a short time (for example, 

take in information, make a decision, and execute a maneuver quickly,) 

their workload is high. 

When drivers make decisions about their route they are navigating or 

wayfinding.

Information Overload, Positive Guidance, Visual Perception at Night, 

Signs, Pavement Markings, Maintenance and Work Zones, Roadway 

Departure on Curves

NCHRP Report 600, “Human Factors Guidelines for Road Systems” has 

more information in Chapter 3, “Finding Information Like a Road User”: 

http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_600second.pdf

The Manual of Uniform Traffic Control Devices (MUTCD) gives specific 

guidance on Signs in Part 2. The information on placement may be 

especially useful: https://mutcd.fhwa.dot.gov/pdfs/2009r1r2/part2a.pdf

Useful Links

Cross-References in this Book

Useful Terms for Further Reading

Road users should not be 

expected to read detailed text 

on a wayfinding sign while 

entering a curve. The blue 

sign should be relocated 

upstream. 

©2017 FormulaNone. 

HUMAN FACTORS PRINCIPLES: PRIORITY OF INFORMATION NEEDS
Practical Safety Solutions for Local and Tribal Roads: 

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Distraction can be addressed through engineering, enforcement and 

education. Practitioners can apply engineering solutions to minimize the 

impact of distracted driving. 

Install rumble strips at edge lines and center lines to alert road users 

when they begin to leave the travel lane. The sound and vibration can 

redirect attention to the driving task. 

Help keep vehicles on the road, provide for safe recovery, and minimize 

the severity of crashes by designing safer slopes/ditches and removing 

hazardous roadside obstacles. 

• Regrade next to the pavement edge to temporarily eliminate edge 

drop-offs and include the SafetyEdge next time pavement is placed to 

permanently eliminate edge drop-off.

• Widen and pave shoulders.

• Widen two-lane roads and include a narrow “buffer” median between 

opposing lanes.

• Install median barriers for narrow medians on multi-lane roads.

Distraction is any activity that takes road users’ attention away from 

their primary driving, cycling, or walking task. Distraction sources can be 

inside or outside the vehicle.

Road use requires attention. The roadway situation can change rapidly, 

and failure to pay attention can cause crashes.

Distraction can cause crashes anywhere in the system. Driving, cycling, 

or walking requires the road user’s full attention, whether it takes place at 

complex curves, intersections, or on straight flat roads.

WHEN and WHERE is this useful?

WHY is this important?

Distraction | Human Factors Principle

WHAT can we do to improve safety?

HUMAN FACTORS PRINCIPLES: DISTRACTION
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

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Longitudinal rumble strips are a series of milled or raised elements 

on or near the center or edge line of a paved roadway. These alert road 

users (through vibration and sound) that their vehicles have left the 

travel lane. 

Transverse rumble strips are a series of milled or raised strips across 

the roadway that act as a warning to road users when approaching a 

curve or intersection. 

A roadway departure (RwD) crash is a crash which occurs after a 

vehicle crosses an edge line or a center line, or otherwise leaves the 

travel way.

Positive Guidance, Information Overload, Pavement Markings, 

Signs, Roadway Departure on Straight Sections, Roadway Departure 

on Curves

Manual on Uniform Traffic Control Devices (MUTCD) gives specific 

guidance on rumble strips: 

https://mutcd.fhwa.dot.gov/pdfs/2009r1r2/mutcd09r1r2editionhl.pdf

Find information about advantages and disadvantages of rumble strips

here: https://safety.fhwa.dot.gov/local_rural/training/fhwasa1109/

The Local Rural Road Owner’s Manual on Roadway Departure gives a 

step-by-step guide for non-engineers: https://safety.fhwa.dot.gov

/local_rural/training/fhwasa1109/fhwasa1109.pdf

Countermeasures for Roadway Departure Crashes: 

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

Useful Links

Cross-References in this Book

Useful Terms for Further Reading

Center line rumble strips

can alert road users when 

they begin to leave the travel 

lane. ©MnDOT. 

HUMAN FACTORS PRINCIPLES: DISTRACTION
Practical Safety Solutions for Local and Tribal Roads: 

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Retroreflective signs and pavement markings are conspicuous at 

night. When well-maintained, these signs and pavement markings can 

communicate essential information about the road ahead. 

• Place signs where headlights will illuminate them. This is especially 

important on curves. 

• Use delineators to highlight the edge of the roadway.

• On unlighted roads, visual information is less easily received by road 

users. They may need more time and distance to acquire information 

before maneuvering. 

• Consider adding lighting where possible. 

• Take older road users into account. Make sure people have enough 

time to see a sign, understand it, and respond. Accommodating older 

people can help all road users. Install median barriers for narrow 

medians on multi-lane roads.

Road users get their information differently at night. Visual information is 

more difficult to acquire while traveling in the dark.

Road users depend on vision to acquire information about the road 

ahead. When traveling in the dark, road users can see only the aspects of 

the road ahead that are illuminated by headlights, street lights, or other 

light sources. Information left in darkness is not detected, and road users 

need more time to detect and understand the illuminated information.

Information conveyed by color may be reduced or lost. Signs and 

markings that are in poor condition are difficult to see and understand.

Nighttime affects road users’ ability to acquire the visual information that 

they need. Advance warning of hazards and upcoming changes in road 

characteristics become even more important at night.

WHEN and WHERE is this useful?

WHY is this important?

WHAT can we do to improve safety?

Visual Perception at Night | Human Factors Principle

HUMAN FACTORS PRINCIPLES: VISUAL PERCEPTION AT NIGHT
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

18

Sign and marking materials that reflect light straight back to the source 

are retroreflective. These materials look bright when headlights shine on 

them.

Positive Guidance, Information Overload, Priority of Information 

Needs, Signs, Pavement Markings, Roadway Departure on Curves

Learn about maintaining Signs here: 

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

dept/night_visib/sign_retro_4page.pdf

Learn about maintaining Pavement Markings here: 

https://safety.fhwa.dot.gov/roadway_dept/night_visib/fhwasa14017/fhwas

a14017.pdf

Find broader resources about older road users here, including the 

Handbook for Designing Roadways for the Aging Population: 

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

Useful Links

Cross-References in this Book

Useful Terms for Further Reading

Retroreflective materials are conspicuous at night. ©MDOT

HUMAN FACTORS PRINCIPLES: VISUAL PERCEPTION AT NIGHT
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

19

Eleven common Safety Challenges are 

covered in the following sections:

Unsignalized Intersections

Signs

Pavement Markings

Roadway Departure on Straight Sections

Roadway Departure on Curves

Speeding

School Zone and School Crossings

Pedestrian Safety

Bicyclist Safety

Work Zone Safety

Unpaved Roads

Safety Challenges

SAFETY CHALLENGES
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

20

An Unsignalized Intersection is a location where two or more 

roads cross that is not controlled by a traffic signal and is not a 

roundabout. Unsignalized Intersections are most commonly controlled 

with stop signs on the minor approaches. A high proportion of crashes 

between two or more road users occur at Unsignalized Intersections. 

Addressing User Expectancies at Unsignalized Intersections will 

enable road users to act appropriately on the approach. 

Limitations on Visual Perception at Night can keep road users from 

acquiring the right information in advance of an intersection. 

An intersection is a conflict point and requires substantial attention from 

the road user. If road users are faced with too many information sources, 

Information Overload may prevent them from finding the most 

necessary information and responding correctly in a timely manner. 

Distraction can affect all aspects of performance including lane-keeping, 

speed selection, hazard detection, decision-making, and safe maneuver 

execution.

WHY are human factors principles important for safety in this topic?

Unsignalized Intersections | Safety Challenge

Road users approaching a skewed intersection may have a User 

Expectancy that the angle of the crossing roads will be 90 degrees. As a 

result, road users may not turn their heads far enough to view cross

traffic. The intersection shown had a crash history of side-impact 

collisions. Installation of stop bars that were parallel to the crossing road 

communicated to road users the skewed angle of the crossing road and 

reduced crashes. ©2019 David Orr

SAFETY CHALLENGES: UNSIGNALIZED INTERSECTIONS
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

21

Strategies to help with user expectancies, Positive Guidance, Visual 

Perception at Night, and Distraction include the following: 

• Maintain clear zones.

• Remove objects that may block the view of the intersection (for 

example, trees, shrubs, parking). 

• Add or maintain appropriate regulatory (stop or yield) signs, 

warning signs, and pavement markings.

• Install signs such as “stop ahead” or “intersection ahead” warning 

signs to notify road users of upcoming intersections. 

• Install flashing beacons at intersections that are controlled by stop 

signs. 

• Provide lighting. 

• Realign skewed intersections to improve road users’ ability to see 

other traffic or retrofit as a roundabout. 

Rumble strips can be used to reduce intersection approach speeds by 

installing them across the travel lanes approaching the intersection. When 

installed across the lane rather than along the edge or center lines, they 

are called transverse rumble strips. 

WHAT can we do to improve safety?

Intersections can be reviewed for safety issues, either proactively or in 

response to crashes. Review existing crash data to find the cause of 

unsignalized intersection crashes and to select the most effective 

solutions. Depending on the nature of the crashes, some solutions may 

attack the problem in a single spot or throughout the network.

WHEN and WHERE is this useful?

SAFETY CHALLENGES: UNSIGNALIZED INTERSECTIONS
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

22

Positive Guidance, Signs, Pavement Markings, User Expectancy, 

Visual Perception at Night, Information Overload, Distraction, Speed

For information on identifying intersection safety issues and selecting the 

proper solution, see Intersection Safety: A Manual for Local Rural Road 

Owners:https://safety.fhwa.dot.gov/local_rural/training

/fhwasa1108/fhwasa1108.pdf.

Unsignalized Intersection Improvement Guide (UIIG) provides a list of 

strategies that could improve safety at Unsignalized Intersections: 

https://toolkits.ite.org/uiig/

The Manual on Uniform Traffic Control Devices (MUTCD) contains 

information on many solutions that could be implemented at 

Unsignalized Intersections: https://mutcd.fhwa.dot.gov/

For additional information on warning signs, see 

https://safety.fhwa.dot.gov/hsip/hrrr/manual/ch4.cfm

Useful Links

Cross-References in this Book

Rumble strips are a series of milled or raised strips across a road or 

along its edge. These rough sections of pavement alert road users 

(through vibration and sound) that their vehicles have left the travel lane. 

The clear zone is an unobstructed roadside area that allows road users 

to stop safely or regain control of a vehicle that has left the roadway. 

Clearing obstructions can assist road users in their view of the road 

ahead and can minimize the consequences of Roadway Departure. 

At most intersections, the roads cross at a right angle (90 degrees). At 

skewed intersections, the intersecting angles are 60 degrees or less.

Useful Terms for Further Reading

SAFETY CHALLENGES: UNSIGNALIZED INTERSECTIONS
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

23

Signs are placed in key locations to guide and regulate traffic. They 

provide information about regulations, warnings, and guidance on the 

roadway using words, symbols, arrows, and color to convey their 

messages.

Signs must be deployed correctly in the following ways:

• Avoid Information Overload by presenting information at a pace and 

complexity that road users can understand and apply. 

• Correct inaccurate User Expectancies by giving road users advance 

information clearly and consistently. 

• Accommodate Visual Perception at Night by maintaining visibility and 

legibility of signs during nighttime conditions.

WHY are human factors principles important for safety in this topic?

Signs | Safety Challenge

SAFETY CHALLENGES: SIGNS

Maintain signs so they can be seen. ©2020 Toxcel
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

24

The following strategies will help avoid Information Overload: 

• Use the fewest signs possible. Too many signs at a single location may 

confuse or overwhelm road users. 

• Keep signs clear and simple. Signs with too many words require longer 

reading times and may cause confusion. 

• Install signs in places where they can easily be seen. 

Address User Expectancies in the following ways:

• Install signs ahead of key locations so that drivers know what to 

expect. Reference the MUTCD when choosing and installing a sign. 

• Use colors, symbols, and abbreviations that are consistent and 

conform to the MUTCD. Keeping signs consistent allows road users to 

recognize them faster. 

• Remove signs that no longer apply. If a hazard has been fixed or 

removed, be sure to remove the warning sign as well. This will help 

maintain sign credibility. 

Accommodate concerns about Visual Perception at Night with the 

following:

• Use retroreflective sign material that is visible during nighttime 

conditions. 

• Consider installing lighting as needed. 

 

WHAT can we do to improve safety?

Place signs where road users need information or guidance. Signs should 

be placed in locations that give users enough time to read and 

understand the information and safely react. Place signs where they will 

be clearly visible.

WHEN and WHERE is this useful?

SAFETY CHALLENGES: SIGNS
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

25

Positive Guidance, Information Overload, Unsignalized 

Intersections, Roadway Departure on Curves, Visual Perception at 

Night, User Expectancy, Speed

For information on signing, see Chapter 2 of the Manual on Uniform 

Traffic Control Devices (MUTCD): https://mutcd.fhwa.dot.gov/

Best practices associated with Signs are included in Chapter 18 of 

NCHRP Report 600: 

http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_600second.pdf

Additional information on the use of signing as a safety treatment: see 

Section 4.8 of the Manual for Selecting Safety Improvements on High 

Risk Rural Roads: https://safety.fhwa.dot.gov/hsip/hrrr/manual/

Useful Links

Cross-References in this Book

When road users can rely on signs to be accurate and useful, signs have 

credibility. 

The amount of information being provided and how hard it may be to 

process is known as sign complexity. 

The amount of time a road user needs to take in information, 

understand it, make a decision, and execute a maneuver is called 

perception-reaction time.

Useful Terms for Further Reading

SAFETY CHALLENGES: SIGNS
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

26

Pavement Markings provide road users with important information 

allowing minimal diversion of attention from their travel task. They outline 

travel lanes, guide road users, and promote safe travel.

Applied correctly, pavement markings can assist safe travel in the 

following ways:

• Avoid Information Overload by using simple markings that road users 

can understand and apply. 

• Use Positive Guidance by giving road users advance information 

clearly and consistently. 

• Accommodate Visual Perception at Night by ensuring visibility and 

legibility of Pavement Markings.

WHY are human factors principles important for safety in this topic?

Pavement Markings | Safety Challenge

Refer to the MUTCD when applying Pavement 

Markings. Some common markings are shown 

to the left. Source: FHWA.

©2019 MnDOT.

System-wide application of appropriate Pavement Markings can reduce 

overall crashes in a jurisdiction more effectively than choosing a small 

number of spot locations. Pavement Markings are considered to be a 

low-cost method to improve safety.

WHEN and WHERE is this useful?

SAFETY CHALLENGES: PAVEMENT MARKINGS
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

27

Avoid Information Overload with the following strategies: 

• Keep text and symbol markings simple. Complex markings require 

more time to understand and may confuse drivers. 

Conform to the principle of Positive Guidance in the following ways:

• Use colors, symbols, and markings that are consistent and conform to 

the MUTCD. Keeping markings consistent allows road users to 

recognize them quickly. 

• Provide enough time for road users to read and safely react to 

Pavement Markings. 

Accommodate concerns about Visual Perception at Night with the 

following:

• Retroreflective pavement markings are easily seen at night, 

especially when well maintained. Use raised pavement markers (RPM) 

to improve visibility during nighttime conditions and inclement weather.

• Maintain Pavement Markings to ensure visibility and legibility.

WHAT can we do to improve safety?

Positive Guidance, Information Overload, Unsignalized 

Intersections, Roadway Departure on Curves, Visual Perception at 

Night, User Expectancy, Speed

For information on markings, see Chapter 3 of the Manual on Uniform 

Traffic Control Devices (MUTCD): https://mutcd.fhwa.dot.gov/

Best practices associated with pavement markings are included in 

Chapter 20 of NCHRP Report 600: 

http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_600second.pdf

Useful Links

Cross-References in this Book

The line that divides traffic traveling in opposite directions is called the 

center line. 

The line that delineates the edge of the travel way is called the edge line. 

Sign text that is painted on the road is called horizontal pavement 

markings.

Pavement Marking materials that reflect light back to the source are 

retroreflective and often use glass beads to reflect light.

Useful Terms for Further Reading

SAFETY CHALLENGES: PAVEMENT MARKINGS
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

28

A Roadway Departure (RwD) crash is a crash which occurs after 

a vehicle crosses an edge line or a center line, or otherwise leaves the 

travel way. 

To effectively prevent RwD crashes and fatalities, FHWA’s efforts to 

reduce RwDs are guided by the Strategic Approach & Plan (see Useful 

Links) that involves countermeasures that: 1) Keep Vehicles on Roadway, 

2) Provide for Safe Recovery, and 3) Reduce Crash Severity.

Vehicle use requires attention. Distraction takes the user’s attention 

away from the driving task and can cause crashes. When a single car or 

truck crashes on a straight section of road (also called a tangent,) it is 

often because the road user is not paying attention to the driving task. 

The road user may be distracted, fatigued or impaired.

WHY are human factors principles important for safety in this topic?

SafetyEdgeSM Source: FHWA

To prevent single vehicle crashes on straight roads, it is likely that you will 

need to review and address a section of road rather than a single point. 

Review crash reports to determine whether Roadway Departure crashes 

are localized (for example, at a bicycle crossing that violates user 

expectancies) or scattered through the system (evidence of distracted 

road users).

WHEN and WHERE is this useful?

Roadway Departure on Straight Sections | Safety Challenge

SAFETY CHALLENGES: ROADWAY DEPARTURE ON STRAIGHT SECTIONS
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

29

Provide for safe recovery and reduce crash severity with the following: 

• Install center line and shoulder rumble strips to alert the road user 

when they begin to leave the lane.

• Eliminate shoulder drop-offs by installing a SafetyEdge. Shoulder 

drop-offs can cause drivers to lose control when they try to re-enter 

the roadway. 

• Widen and/or pave shoulders as appropriate. 

• On two-lane roads, include a narrow “buffer” median between 

opposing lanes. 

• Install median barriers for narrow medians on multi-lane roads. 

• Install high friction surface treatments on problematic curves. The 

need for pavement friction is higher at curves, and friction degrades 

with each vehicle that takes the curve.

WHAT can we do to improve safety?

Distraction, User Expectancy, Pavement Markings, Signs

The Local Rural Road Owner’s Manual on Roadway Departure gives a 

step-by-step guide for non-engineers: 

https://safety.fhwa.dot.gov/local_rural/training/fhwasa1109/

Countermeasures for Roadway Departure Crashes is more technical: 

https://safety.fhwa.dot.gov/roadway_dept/ and gives information about 

SafetyEdge that may help you fix shoulder drop-offs: 

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

The MUTCD gives specific guidance on rumble strips: 

https://mutcd.fhwa.dot.gov/htm/2009/part3/part3j.htm#figure3J01 

More information about SafetyEdges and shoulder drop-off can be found 

in NCHRP Report 600: 

http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_600second.pdf

Useful Links

Cross-References in this Book

The clear zone is an unobstructed roadside area that allows road users 

to stop safely or regain control of a vehicle that has left the roadway. 

Clearing obstructions can assist road users in their view of the road 

ahead and can minimize the consequences of Roadway Departure. 

Useful Terms for Further Reading

SAFETY CHALLENGES: ROADWAY DEPARTURE ON STRAIGHT SECTIONS 
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

30

A Roadway Departure (RwD) crash occurs after a vehicle crosses 

an edge line or a center line, or otherwise leaves the travel way. 

Vehicles are more likely to leave the travel lane of a roadway where the 

roadway curves to the right or left.

When a single car or truck leaves the roadway on a curved section, it is 

often because the road user has lost control of the vehicle. Appropriate 

speed selection is needed to safely navigate roadway curves. Road users 

are more likely to lose control when User Expectancy is violated, when 

there is Distraction, or when accurate advance information has not been

provided at the right location through proper Positive Guidance. 

To effectively prevent RwD crashes and fatalities, FHWA’s efforts to 

reduce RwDs are guided by the Strategic Approach & Plan (See Useful 

Links) that involves countermeasures that: 1) Keep Vehicles on Roadway, 

2) Provide for Safe Recovery, and 3) Reduce Crash Severity.

WHY are human factors principles important for safety in this topic?

Roadway Departure on Curves | Safety Challenge

Before- and After- photos show countermeasures designed to help road 

users detect the upcoming curve. Used with permission. ©Iowa Department 

of Transportation and ©The Ohio Department of Transportation.

Curves are common locations for RwD crashes. Violations of road users’ 

expectations or a lack of advance information may lead them to select an 

inappropriate speed on approach and conduct inappropriate maneuvers 

without adequate time to adjust accordingly. This is more likely at the 

following locations:

• A curve following a long straight section of roadway,

• A sharp curve after a series of gentle curves,

• Locations where road users cannot see the curve ahead, which may 

occur at night on unlighted roads or where sight distance is limited.

WHEN and WHERE is this useful?

SAFETY CHALLENGES: ROADWAY DEPARTURE ON CURVES
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

31

Review crash reports to identify contributing factors. Collect additional 

information through site visits and discussions with law enforcement and 

the public. When selecting countermeasures, consider the following: 

Visual Perception at Night for nighttime crashes; user expectancies for 

hot spot curves, and Positive Guidance for advance warning needs. 

Keep vehicles on the roadway with the following countermeasures: 

• Install shoulder and/or center line rumble strips to alert the road 

users to lane departure. 

• Guide road users at night by adding and placing signs and delineators 

where headlights will illuminate them. 

Help road users prepare for the correct maneuvers and select the 

appropriate speed to safely navigate the curve with the following 

strategies: 

• Install chevrons to guide drivers through curves. 

• Install reflectors (such as post-mounted delineators or raised pavement 

markers) before and through curves. 

• Install curve warning signs and advisory speed limit signs before 

sharp curves, maintaining consistency across the system. 

• Install high friction surface treatments on problematic curves. 

Provide for safe recovery and reduce crash severity with the following: 

• Eliminate shoulder drop-offs or install a SafetyEdge. 

• Widen and/or pave shoulders as appropriate. 

• On two-lane roads, include a narrow “buffer” median between opposing 

lanes. 

• Install median barriers for narrow medians on multi-lane roads. 

• Minimize overturning by designing safer slopes/ditches and removing 

hazardous roadside obstacles in the clear zone. 

WHAT can we do to improve safety?

The path or direction a roadway takes – curves or straight sections - is 

known as the alignment. 

When the road bends to the right or to the left, that’s a horizontal curve. 

Chevrons are simple arrow signs that indicate the alignment of a curve. 

Chevrons can be seen in the photo on page 30.

Useful Terms for Further Reading

SAFETY CHALLENGES: ROADWAY DEPARTURE ON CURVES
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

32

Pavement Markings, Signs, User Expectancy, Visual Perception at 

Night, Speed, Distraction

For information on identifying roadway departure safety issues and 

selecting the solutions to address those issues, see Roadway Departure 

Safety: A Manual for Local Rural Road Owners: https://safety.fhwa.dot.

gov/local_rural/training/fhwasa1109/fhwasa1109.pdf

Horizontal Curve Safety (FHWA) lists potential strategies that can be 

implemented to improve curve safety: 

https://safety.fhwa.dot.gov/roadway_dept/horicurves/cmhoricurves/horiz_

curve.pdf

Additional information on potential solutions for safety problems on curves 

can be found in Low-Cost Treatments for Horizontal Curve Safety: 

https://safety.fhwa.dot.gov/roadway_dept/horicurves/fhwasa15084/fhwasa

15084rev011720_508_FINAL.pdf. Information on advance warning 

signs can be found on Chapter 4, Table 4 

For information on warning signs that could be placed ahead of curves, 

see Chapter 2C in the Manual on Uniform Traffic Control Devices 

(MUTCD): https://mutcd.fhwa.dot.gov/pdfs/2003/Ch2C.pdf

For additional information on safety treatments for horizontal curves, see 

Section 4.1 of the Manual for Selecting Safety Improvements on High 

Risk Rural Roads: https://safety.fhwa.dot.gov/hsip/hrrr/manual/

For additional information on advisory speeds on curves, see 

https://safety.fhwa.dot.gov/speedmgt/ref_mats/fhwasa1122

/fhwasa1122.pdf

For additional information on high friction surface treatments, see 

https://safety.fhwa.dot.gov/roadway_dept/pavement_friction/high_friction/

Useful Links

Cross-References in this Book

SAFETY CHALLENGES: ROADWAY DEPARTURE ON CURVES

A speed below the speed limit that is recommended for a section of 

highway is the advisory speed and is normally determined through an 

engineering study.

High friction surface treatments can dramatically and immediately 

reduce crashes, injuries, and fatalities associated with friction demand 

issues.

Useful Terms for Further Reading (Cont.)
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

33

Speeding is driving above the posted speed limit or driving too fast for 

conditions.

Human factors principles can offer strategies to help road users choose a 

safe speed. 

Strategies include giving road users information for appropriate speed 

selection and by increasing their awareness of speed.

WHY are human factors principles important for safety in this topic?

Speeding | Safety Challenge

Road users tend to speed in areas that lack traffic signals and stop signs, 

that have lower traffic volumes, and that show only sporadic speed 

enforcement activity. Some roadways may encourage higher speeds; flat, 

wide roads can be associated with a User Expectancy that speeds 

should be high. Speeding can also be a result of Distraction, as road 

users may not realize that they are traveling too fast. 

Crash reports and police citations can help determine if there is a 

Speeding issue. Physical evidence such as skid marks, sign 

knockdowns, and guardrail strikes may indicate a Speeding problem. 

Coordinate with local law enforcement whenever possible.

WHEN and WHERE is this useful?

Use strategies for self-enforcing roadways with signs and pavement 

markings that communicate safe speed selection to road users.

• Install advisory speed signs before curves. 

• Install a speed activated sign that alerts road users when they are 

driving too fast. 

• Install optical speed bars at spot locations. 

• Increase road users’ awareness of speed by installing transverse 

rumble strips across the travel lane at decreasing intervals. 

• Install speed tables or speed humps. 

• Install mini-roundabouts.

WHAT can we do to improve safety?

SAFETY CHALLENGES: SPEEDING
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

34

Optical speed bars can increase perceived speed and reduce travel speed.

©Virginia Center for Transportation Innovation and Research.

The speed selected for the roadway during the design process is called 

the design speed.

The speed that vehicles travel when they are undisturbed by traffic or 

traffic control devices is called the operating speed.

The highest lawful speed vehicles can travel at is the posted speed. 

The numerical speed established by state law is called the statutory 

speed. 

The use of design features to reduce travel speeds is called traffic 

calming. 

Road users make inferences about speed selection and expected 

maneuvers based on physical characteristics of the roadway. A selfenforcing road has characteristics that lead users to select appropriate 

speeds.

A speed below the speed limit that is recommended for a section of 

highway is the advisory speed. The advisory speed is normally 

determined through an engineering study that considers highway design, 

operating characteristics and conditions. 

The section of roadway before a motorist enters a community, where 

drivers need to identify an upcoming change in roadway character and 

reduce travel speed in preparation for entering the community is a 

transition zone. 

Useful Terms for Further Reading

SAFETY CHALLENGES: SPEEDING
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

35

Distraction, Signs, Pavement Markings, User Expectancy

For information on how to address speed-related crashes, see Speed 

Management: A Manual for Local Rural Road Owners:

https://safety.fhwa.dot.gov/local_rural/training/fhwasa010413spmgmt/spe

edmanagementguide.pdf

For information on setting speed limits, see Methods and Practices for 

Setting Speed Limits: An Informational Report: 

https://safety.fhwa.dot.gov/speedmgt/ref_mats/fhwasa12004/

See Chapter 17 of NCHRP Report 600 for information on Speeding: 

http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_600second.pdf

Manual on Uniform Traffic Control Devices (MUTCD) contains information 

on many solutions that could be implemented to reduce Speeding: 

https://mutcd.fhwa.dot.gov/htm/2009/html_index.htm

For a list of traffic calming strategies, see the FHWA Traffic Calming 

ePrimer – Toolbox of Individual Traffic Calming Measures: 

https://safety.fhwa.dot.gov/speedmgt/ePrimer_modules/module3

.cfm#mod31

USLIMITS2 is a tool to aid practitioners in determining appropriate speed 

limit recommendations: https://safety.fhwa.dot.gov/uslimits/index.cfm

Self-enforcing roadways report: 

https://www.fhwa.dot.gov/publications/research/safety/17098/17098.pdf

For additional information on transition zones, see 

https://safety.fhwa.dot.gov/speedmgt/ref_mats/rural_transition_

speed_zones.cfm

Useful Links 

Cross-References in this Book

SAFETY CHALLENGES: SPEEDING
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

36

A School Zone is an area on a street near a school or near a 

crosswalk that leads to a school. A School Crossing is a crosswalk 

that leads to a school.

Children have difficulty judging speeds and safe gaps in traffic. When 

crashes occur in a School Zone, they are often due to inexperience, 

Distraction, or Speeding.

Strategies center on alerting road users and offering them accurate 

information for safe travel.

WHY are human factors principles important for safety in this topic?

School Zones and School Crossings | Safety Challenge

User Expectancies can determine whether road users select appropriate 

speeds and prepare the correct responses in a School Zone or at a 

School Crossing. When road users are informed of the presence of 

children, other pedestrians and bicyclists, they are more likely to respond 

appropriately. 

Road users in motorized vehicles are less likely to expect vulnerable road 

users on roads that are heavily traveled; have more than two lanes; or are 

in rural, commercial, or industrial areas. When sight distance is limited, 

the hazard increases.

WHEN and WHERE is this useful?

Consult the MUTCD Chapter 7 for guidance on the placement of 

School Zone and School Crossing signs. ©2013/2019 VHB

SAFETY CHALLENGE: SCHOOL ZONES AND SCHOOL CROSSINGS
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

37

Alert road users and offer them information so they can prepare 

appropriate responses. Road users can be prepared for children with use 

of the following methods: 

• Install signs to warn road users that they are approaching a School 

Zone or Crossing. 

• Install signs in places where they are easily seen. 

• Install crosswalks to guide pedestrians. Use high-visibility markings to 

ensure that they are seen by other road users. 

• Use in-street pedestrian crossing signs to highlight crosswalks near 

schools. 

• Install lighting to improve pedestrian visibility.

• Install flashing LED beacons to warn road users of crossing 

pedestrians. 

• Reduce speeds at School Zones to give road users more time to 

react. Slower speeds also create safer gaps for children to cross the 

roadway. 

• Install flashing School Zone signs that clearly display the speed limit to 

capture the attention of distracted road users. 

• Use countermeasures that apply to pedestrians and bicyclists in 

general. 

• Coordinate with law enforcement to enforce safe travel around schools.

WHAT can we do to improve safety?

The amount of time a road user needs to perceive and understand 

information, make a decision, and execute the response is called 

perception-reaction time. 

Useful Terms for Further Reading

SAFETY CHALLENGE: SCHOOL ZONES AND SCHOOL CROSSINGS
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

38

User Expectancy, Distraction, Speed, Signs, Pavement Markings,

Pedestrians, Bicycles

Information on how to manage speed near School Zones and 

Crossings is found in Speed Management: A Manual for Local Rural 

Road Owners 

https://safety.fhwa.dot.gov/local_rural/training/fhwasa010413spmgmt/spe

edmanagementguide.pdf

NCHRP Report 600 (Chapter 17) 

http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_600second.pdfSecti

on 15-6 lists methods to reduce driver speeds in School Zones

Manual on Uniform Traffic Control Devices (MUTCD) 

https://mutcd.fhwa.dot.gov/htm/2009/html_index.htm

Useful Links

Cross-References in this Book

SAFETY CHALLENGE: SCHOOL ZONES AND SCHOOL CROSSINGS
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

39

Pedestrians face daily challenges and safety concerns when using 

the same roadway as motorized vehicles.

Pedestrians behave differently from motor vehicles. They move more 

slowly than motor vehicles, and their speed and behavior is greatly 

affected by factors like age, physical limitations, and cognitive abilities. 

Pedestrians react to features that drivers cannot see, such as puddles, 

and may perform actions that drivers do not expect. Pedestrians are 

physically vulnerable.

Proper facilities such as crosswalks, pedestrian facilities, sidewalks, or 

paved shoulders can enhance the safety of pedestrians. Pedestrians may 

use the roadway with motorized vehicles, resulting in unsafe conditions 

and drivers do not expect to see pedestrians. Lighting, weather, and 

clothing choices can affect visibility, especially during bad weather or at 

night. In many places, motor vehicle drivers do not expect the presence of 

pedestrians. Distraction on the part of any road user can be an 

underlying cause in crashes.

WHY are human factors principles important for safety in this topic?

Pedestrian Safety | Safety Challenge

Pedestrian Safety issues can appear anywhere that motor vehicles and 

pedestrians must interact. An understanding of User Expectancies, 

Visual Perception at Night, and Speeding can help to identify 

underlying human factors issues. Review crash reports and citations to 

identify safety issues involving pedestrians. Depending on the nature of 

the crashes, the problem may be addressed in a single spot or may 

involve a larger area such as a corridor.

WHEN and WHERE is this useful?

Shared use path

crossing with signs 

and horizontal 

pavement markings

to alert road 

users.©2018 

Montgomery County 

Planning Commission.

SAFETY CHALLENGE: PEDESTRIAN SAFETY
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

40

Know the population and context. Pedestrian crashes next to a school 

may require different solutions than pedestrian crashes outside a popular 

bar. Choose solutions accordingly. 

Alert road users and give them information with the following strategies: 

• Install signs that alert road users to potential pedestrians crossing the 

roadway. 

• Install Pavement Markings that highlight pedestrian crossings. 

• Install crosswalks and pedestrian crossing signage to notify road users 

that they must yield or stop for pedestrians. 

• Install transverse rumble strips across the travel lane to alert road 

users that they must slow down ahead. 

• Accommodate Visual Perception at Night by adding lighting when 

possible.

• Install flashing LED beacons to warn road users about a crossing 

pedestrian. 

• Separate pedestrians from vehicle traffic whenever possible (for 

example, by installing sidewalks or walkways). Consider a road diet, 

reducing the number of travel lanes to provide space for sidewalks 

and/or medians.

• Consider installing shared use paths.

• Install refuge islands in the middle of roadways to allow pedestrians to 

safely cross multilane roads. 

• Educate all road users on how to safely share roadways.

WHAT can we do to improve safety?

SAFETY CHALLENGE: PEDESTRIAN SAFETY
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

41

Pavement Markings, Signs, Visual Perception at Night, Distraction, 

Positive Guidance

Non-Motorized User Safety: A Manual for Local Rural Road Owners 

provides a toolbox of resources and information for addressing the safety 

of non-motorized users: https://safety.fhwa.dot.gov/local_rural/

training/fhwasa010413/nonmotorize.pdf. See Appendix A for a list of 

countermeasures 

For information on common crash factors and potential solutions, see 

Factors Contributing to Pedestrian and Bicycle Crashes on Rural 

Highways: https://www.fhwa.dot.gov/publications/research/safety/10052/

Manual on Uniform Traffic Control Devices (MUTCD) 

https://mutcd.fhwa.dot.gov/htm/2009/html_index.htm 

See Section 2C.50 for information on non-vehicular warning signs

See Section 3B.18 for information on crosswalk markings

Learn more about Pedestrian and Bicycle Safety here:

https://safety.fhwa.dot.gov/ped_bike/ and here: 

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

Useful Links

Cross-References in this Book

Reducing the number of travel lanes to provide space for bicycle lanes, 

sidewalks, or medians is called a road diet. 

A path separated from a roadway that can be used by cyclists, 

pedestrians, and other non-motorized users is called a shared use path.

Useful Terms for Further Reading

SAFETY CHALLENGE: PEDESTRIAN SAFETY
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

42

Bicyclists face daily challenges and safety concerns when using the 

same roadway as motorized vehicles. Scooters and other wheeled nonmotorized vehicles share many of the same challenges as bicycles.

Bicyclists often move more slowly than motor vehicles, and their speed 

and behavior is greatly affected by factors like age and physical abilities. 

Bicycles are more affected by pavement condition than motor vehicles, 

and cyclists may react to avoid conditions that drivers cannot see. In 

many locations, bicyclists are relatively rare, so other road users often do 

not expect their presence. 

Bicycle facilities (bike lanes, shared paths) can enhance the safety of 

bicyclists and other road users. Lighting, weather, and clothing choices 

can affect visibility, especially during bad weather or at night. Distraction

on the part of any road user can be an underlying cause in crashes. 

Bicyclists and other non-motorized users are physically vulnerable.

WHY are human factors principles important for safety in this topic?

Bicyclist Safety | Safety Challenge

Bicyclist Safety issues can arise in any part of the system where road 

users include cyclists. Though bicyclists may travel more slowly than 

many motorized vehicles, it’s important to allow enough time for cyclists to 

take in information, understand it, and respond appropriately. Drivers 

should be made aware of the presence of bicyclists and the need to share 

the roadway.

An understanding of User Expectancies, Distraction, and Visual 

Perception at Night can help to identify underlying issues and choose 

effective countermeasures. 

Review crash reports and citations to identify safety issues involving 

bicyclists. Depending on the nature of the crashes, the problem may be 

addressed in a single spot or may involve a larger area. For example, 

nighttime crashes may suggest the need to accommodate Visual 

Perception at Night. Crashes at a specific crossing may require Positive 

Guidance to help road users prepare the appropriate responses.

WHEN and WHERE is this useful?

SAFETY CHALLENGE: BICYCLIST SAFETY
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

43

Know how road users travel through your network. Incidents next to a 

school may require different solutions than bicycle incidents in a 

commuter corridor or recreational area. Choose solutions accordingly. 

Strategies to protect bicyclists include alerting distracted road users, 

accommodating Visual Perception at Night, providing users with 

information that will help them maneuver appropriately, and minimizing 

the consequences of road user error by physically separating cyclists 

from motorized traffic.

• Install signs that alert road users to potential cyclists on the roadway. 

• Install pavement marking symbols that help cyclists on the roadway 

and alert road users.

• Install pavement markings that highlight bicycle crossings. 

 

WHAT can we do to improve safety?

Source: ©2018 VHB

Road diet reduces travel lanes to provide space for bicycle lanes 

and turning lane. ©MoBikeFed

SAFETY CHALLENGE: BICYCLIST SAFETY
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

44

• Install flashing LED beacons to warn road users about a crossing such 

as trail crossings. 

• Accommodate concerns about Visual Perception at Night by 

installing lighting along roadways where applicable. 

• Separate vehicle traffic from bicyclists whenever possible: provide bike 

paths, separated bike lanes on popular biking corridors, shared use 

paths, or bike boulevard/greenways in urban areas.

• Install raised islands in the middle of roadways to allow cyclists to 

safely cross multilane roads. 

• Consider a road diet, reducing the number of travel lanes to provide 

space for bicycle lanes and/or medians. 

• Place Signs and other information accordingly, being mindful of the 

Priority of Information Needs. 

• Educate all road users on how to safely share roadways.

WHAT can we do to improve safety? (Cont.)

Pavement Markings, Signs, Visual Perception at Night, Distraction, 

Positive Guidance, Priority of Information Needs

Non-Motorized User Safety: A Manual for Local Rural Road Owners 

provides a toolbox of resources and information for addressing the safety 

of non-motorized users: https://safety.fhwa.dot.gov/local_rural/

training/fhwasa010413/nonmotorize.pdf

For information on common crash factors and potential solutions, see 

Factors Contributing to Pedestrian and Bicycle Crashes on Rural 

Highways: http://www.trb.org/Main/Blurbs/163774.aspx

Learn more about Pedestrian and Bicycle Safety here: 

https://safety.fhwa.dot.gov/ped_bike/ and here: 

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

Useful Links

Cross-References in this Book

Reducing the number of travel lanes to provide space for bicycle lanes, 

sidewalks, or medians is called a road diet.

A path separated from a roadway that can be used by cyclists, 

pedestrians, and other non-motorized users is called a shared use path.

Useful Terms for Further Reading

SAFETY CHALLENGE: BICYCLIST SAFETY
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

45

A Work Zone is an area of roadway that is undergoing construction, 

maintenance, or utility work. They are typically marked by signs, barriers, 

Pavement Markings, and work vehicles. Workers may or may not be 

present.

When crashes occur in a maintenance or work zone, they can be a result 

of Distraction or Speeding. Work zones also present unexpected 

conditions, such as reduced sight distance, changes to signs and 

markings, and shifts in the travel way. Road users can become confused 

by Information Overload.

WHY are human factors principles important for safety in this topic?

Work Zone Safety | Safety Challenge

In the presence of a work zone, measures must be taken to provide for 

safe and efficient travel. The type of safety measures used depends on 

the type and duration of the work being done on a roadway.

WHEN and WHERE is this useful?

Provide the correct level of information according to the Priority of 

Information Needs and avoid Information Overload with the following 

strategies:

• Ensure that the work zone is set up according to guidelines in the 

Manual on Uniform Traffic Control Devices (MUTCD). This includes 

temporary maintenance projects. Make sure that workers follow 

guidelines about the advance placement of warning signs, cones, 

delineation, and barriers. 

• Use appropriate signs and Pavement Markings to provide clear 

guidance on how to get through the work zone. 

• When using electronic message signs, keep messages clear and 

simple. 

• Install signs in places where they can easily be seen and read. 

• Offer information regarding speed selection and upcoming features. 

Set appropriate work zone speed limits to maintain safe traffic flow. 

Limits that are 10 mph below the usual limit are most likely to reduce 

speeds and gain compliance. 

• Accommodate Visual Perception at Night by using signs and traffic 

control devices that are visible during nighttime conditions and install 

appropriate work zone lighting to minimize glare to motorists.

WHAT can we do to improve safety?

SAFETY CHALLENGE: WORK ZONE SAFETY
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

46

Work zones can be complex and confusing for road users.

©2007 Minnesota DOT.

Information Overload, User Expectancy, Distraction, Positive 

Guidance, Signs, Speed, Visual Perception at Night

See Chapter 13 of NCHRP Report 600 for information on work zones: 

http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_600second.pdf

For information on the parts of a temporary traffic control zone and traffic 

control devices, see the Maintenance Work Zone Safety: Pocket Guide 

of MUTCD Guidance on Temporary Traffic Control: 

https://www.workzonesafety.org/trainingresources/fhwa_wz_grant/atssa_maintenance_wz_safety/

Useful Links

Cross-References in this Book

The control of road users through construction, utility, and maintenance 

operations is called temporary traffic control. 

The portion of the roadway closed to road users where the work takes 

place is called the work space. 

An electronic traffic sign used to give road users information is called a 

changeable message sign. 

Useful Terms for Further Reading

SAFETY CHALLENGE: WORK ZONE SAFETY
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

47

Unpaved Roads have gravel, dirt, or sand surfaces. These facilities 

usually carry low volumes of traffic and typically lack Pavement Markings 

and shoulders.

When a crash occurs on an Unpaved Road, it is often due to the road 

surface, visibility or sight distance issues, Distraction, inexperience, or 

a lack of information in the form of signage and Pavement Markings. 

Speed can be a factor. The lack of roadway safety features, such as 

shoulders and Pavement Markings, mean that less information is 

conveyed to the road user. 

Consider these human factors principles when choosing strategies to 

improve safety: Positive Guidance to improve the information offered to 

road users, accommodating Visual Perception at Night, providing for 

safe recovery, and reducing crash severity.

WHY are human factors principles important for safety in this topic?

Unpaved Roads | Safety Challenge

Examine crash reports to find the cause of crashes on Unpaved Roads

and to select the most effective solution. For example, crashes at 

uncontrolled intersections may require clearing vegetation to improve 

sight distance, particularly on low volume roads where User 

Expectancy leads road users to expect limited crossing traffic.

WHEN and WHERE is this useful?

Unpaved Roads usually lack safety features such as Pavement 

Markings. ©2019 Erica Dryden

SAFETY CHALLENGE: UNPAVED ROADS
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

48

Use Positive Guidance by offering advance information. 

• Install delineators to highlight the alignment of the road 

• Install advance warning signs near narrow segments of road and 

before curves. 

• Clear vegetation within the right of way to improve visibility and sight 

distance. Maintaining the clear zone can reduce the incidence and 

severity of crashes.

• Accommodate Visual Perception at Night by placing retroreflective 

signs and delineators where they will be struck by headlights. 

• Maintain the road surface to prevent erosion, washouts, and visibility 

issues caused by too much dust. 

• Construct proper drainage along the roadway. 

• Harden unpaved surfaces by using dust control additives. 

• Provide high quality gravel for the road surface and maintain the 

crown. 

• Consider adding lighting if possible, especially at intersections. 

• Reduce crash severity by designing safer slopes/ditches and removing 

hazardous roadside obstacles.

WHAT can we do to improve safety?

The clear zone is an unobstructed roadside area that allows road users 

to stop safely or regain control of a vehicle that has left the roadway. 

Clearing obstructions can assist road users in their view of the road 

ahead and can minimize the consequences of Roadway Departure. 

The cross-section roadway shape in which the center of the road is higher 

than the outer edges is called the crown. 

A reflective device located on the side of a roadway to indicate alignment

is called a delineator.

Useful Terms for Further Reading

SAFETY CHALLENGE: UNPAVED ROADS
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

49

SAFETY CHALLENGE: UNPAVED ROADS

Signs, Visual Perception at Night, Positive Guidance, User 

Expectancy

Information on safety concerns and solutions along Unpaved Roads can 

be found in the Local and Rural Road Safety Briefing Sheets – Unpaved 

Roads: Safety Needs and Treatments: 

https://safety.fhwa.dot.gov/local_rural/training/fhwasa14094/unpaved.pdf

Information on Unpaved Roads maintenance and proper materials can 

be found in the Gravel Roads Construction and Maintenance Guide: 

https://www.fhwa.dot.gov/construction/pubs/ots15002.pdf

For additional information on the maintenance of gravel roads, see 

Section 4.5 of the Manual for Selecting Safety Improvements on High 

Risk Rural Roads: https://safety.fhwa.dot.gov/hsip/hrrr/manual/

Useful Links

Cross-References in this Book
Practical Safety Solutions: 

A Handbook of Human and Roadway Interaction for Local and Tribal Roads

50
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

51

Cross-Reference Table

Human Factors Principles are interrelated with each other and with 

the Safety Challenges. This Cross-Reference Table shows the most 

closely-related topics. As you use this resource, you will discover 

that accessing multiple sections will help your understanding and 

applications. Use this table and the cross-linked topics to find 

related Human Factors Principles and Safety Challenges. INFORMATION OVERLOAD POSITIVE GUIDANCE USER EXPECTANCY

PRIORITY OF INFORMATION NEEDSDISTRACTIONVISUAL PERCEPTION AT NIGHT

INFORMATION OVERLOAD 

POSITIVE GUIDANCE 

USER EXPECTANCY 

PRIORITY OF INFORMATION NEEDS 

DISTRACTION 

VISUAL PERCEPTION AT NIGHT 

UNSIGNALIZED INTERSECTIONS 

SIGNS 

PAVEMENT MARKINGS 

ROADWAY DEPARTURE ON STRAIGHT SECTIONS 

ROADWAY DEPARTURE ON CURVES 

SPEEDING 

SCHOOL ZONES & CROSSINGS 

PEDESTRIAN SAFETY 

BICYCLIST SAFETY 

WORK ZONE SAFETY 

UNPAVED ROADS 

Human Factors 

Principle Cross Reference

Safety Challenge 

Cross Reference

CROSS REFERENCE TABLE
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

52

UNSIGNALIZED INTERSECTIONSSIGNSPAVEMENT MARKINGSROADWAY DEPARTURE ON STRAIGHT SECTIONSROADWAY DEPARTURE ON CURVESSPEEDINGSCHOOL ZONES & CROSSINGSPEDESTRIAN SAFETYBICYCLIST SAFETYWORK ZONE SAFETYUNPAVED ROADS

CROSS REFERENCE TABLE
Practical Safety Solutions for Local and Tribal Roads: 

A Human Factors Approach

53

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