UNIT 1: Foundations of Road Safety

Road Safety 

Fundamentals

Concepts, Strategies, and Practices that 

Reduce Fatalities and Injuries on the Road
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This document can be downloaded for free in full or by individual unit at: 

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1. Report No.

FHWA-SA-18-003

4. Title and Subtitle

Road Safety Fundamentals:

Concepts, Strategies, and Practices that Reduce Fatalities and Injuries

on the Road

7. Author(s)

Lead Editor: Daniel Carter, P.E., Senior Research Associate

Unit Authors: 

Unit 1: Dan Gelinne, Program Coordinator, UNC Highway Safety 

Research Center 

Unit 2: Bevan Kirley, Research Associate, UNC Highway Safety Research 

Center 

Unit 3: Carl Sundstrom, P.E., Research Associate, UNC Highway Safety 

Research Center 

Unit 4: Raghavan Srinivasan, Ph.D., Senior Transportation Research 

Engineer; Daniel Carter 

Unit 5: Daniel Carter; Jennifer Palcher-Silliman, Communications 

Manager, UNC Highway Safety Research Center

Layout and Graphics: Graham Russell, Graphic Designer, UNC Highway 

Safety Research Center

Technical Editors: Jennifer Palcher-Silliman; Patty Harrison, 

Communications Specialist, UNC Highway Safety Research Center; 

Caroline Mozingo, Senior Manager of Communications, Education and 

Outreach, UNC Highway Safety Research Center

9. Performing Organization Name

and Address

University of North Carolina,

Highway Safety Research Center

12. Sponsoring Agency Name and Address

Federal Highway Administration Office of Safety

1200 New Jersey Ave., SE

Washington, DC 20590

14. Sponsoring Agency Code

15. Supplementary Notes

The project manager for the textbook was Felix H. Delgado, P.E., FHWA Office of Safety

16. Abstract

This book provides an introduction to the fundamental concepts of road safety. The book’s goal is to equip

the reader with a broad base of knowledge about road safety. Thus, the focus is in communicating concepts

rather than providing instruction in detailed analysis procedures.

The audience for this book is two-fold. First, this is intended for those whose job addresses some aspect of 

road safety, particularly in a public agency setting. Second, this book is intended for professors and 

students in a university setting.

This book seeks to lay the foundation of road safety knowledge regardless of a particular discipline. 

Professionals with a background in engineering, planning, public health, law enforcement, and other 

disciplines will benefit from the concepts presented here.

17. Key Words

road safety, road safety management process, site-level management, system

level management, human behavior, safety performance measures, road safety

data, multidisciplinary approaches

18. Distribution Statement

No restrictions

19. Security Classif.

(of this report)

Unclassified

20. Security Classif.

(of this report)

Unclassified

21. No. of Pages

188

22. Price

FREE

5. Report Date

November 2017

6. Performing Organization Code

8. Performing Organization Report No.

10. Work No. (TRAIS)

11. Contract or Grant No.

13. Type of Report and Period Covered

Text book

2. Government Accession No. 3. Recipient’s Catalog No.

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

UNIT 1 Foundations of Road Safety Chapter 1: Context of Road Safety

 Chapter 2: Road Safety Through the Years

 Chapter 3: Multidisciplinary Approaches

 Chapter 4: Road Users

UNIT 2 Human Behavior and Road Safety

 Chapter 5: Understanding Human Behavior

 Chapter 6: Changing Human Behavior

UNIT 3 Measuring Safety

 Chapter 7: Importance of Safety Data

 Chapter 8: Types of Safety Data

 Chapter 9: Improving Safety Data Quality

UNIT 4 Solving Safety Problems

 Chapter 10: Road Safety Management Process

 Chapter 11: Site-Level Safety Management

 Chapter 12: System-Level Safety Management

UNIT 5 Implementing Road Safety Efforts

 Chapter 13: Who Does What

 Chapter 14: Road Safety Research

 Chapter 15: Strategic Communications

 Chapter 16: Advancing Road Safety

TABLE OF CONTENTS

ROAD SAFETY FUNDAMENTALS i
1-b UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

After reading the chapters and completing 

exercises in Unit 1, the reader will be able to:

J DESCRIBE the importance of road 

safety and how it relates to public 

health, economic, environmental 

and demographic trends

J RECOGNIZE roles and responsibilities 

of various disciplines and approaches 

to improving road safety

J DISTINGUISH between nominal 

and substantive safety

J IDENTIFY key points in the history of 

road safety in the U.S., including key 

legislation and agency formation, and 

understand how these decisions have 

shaped today’s roadways

J IDENTIFY different groups of road users 

and challenges unique to each group

LEARNING OBJECTIVES

Foundations 

of Road Safety

UNIT 1
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-1

Context of Road Safety

Road safety is an important part 

of everyday life. Across the nation, 

people use roads and sidewalks to 

get to work, school, stores, and 

home. Public agencies work to 

ensure that people arrive at their 

destination without incident. 

However, not every trip is without 

incident. Deaths and injuries 

resulting from motor vehicle crashes 

represent a significant public 

health concern. The World Health 

Organization (WHO) estimates that 

motor vehicle crashes kill more than 1 

million people around the world each 

year, and seriously injure as many as 

20 to 50 million.1

 These crashes affect 

all road users, from vehicle drivers 

and passengers to pedestrians, 

bicyclists, and transit users. 

Though road safety in the U.S. 

has steadily improved over 

time, it remains a priority for 

transportation agencies, legislators, 

and advocacy organizations. Over 

the past 10 years in the U.S., an 

average of approximately 37,000 

people were killed each year and 

an estimated 2.3 million were 

injured in motor vehicle crashes.2

 

While many of these deaths and 

injuries are sustained by motor 

vehicle passengers and drivers, 

CHAPTER 1 FOUNDATIONS OF ROAD SAFETY

http://www.who.int/

features/factfiles/

roadsafety/en

National Highway 

Traffic Safety 

Administration 

(NHTSA). Fatality 

Analysis Reporting 

System (FARS). 

http://www.nhtsa.

gov/FARS

1983

50,000

fatalities

40,000

30,000

20,000

10,000

198819931998200320082013

Vehicle Occupants

Motorcyclists

Other/Unknown

Pedestrians

bicyclists

FIGURE 1-1: Traffic Fatalities in the U.S. by Year, 1983-2013 (Source: NHTSA FARS)

FIGURE 1-2: Traffic Fatalities in the U.S. by 

Person Type, 2013 (Source: NHTSA FARS)

1

2
1-2 UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

they also impact motorcyclists, 

pedestrians, bicyclists, and users 

of transit vehicles. This challenge 

requires a comprehensive approach 

to improving safety, involving 

numerous stakeholders and 

decision makers from a variety of 

perspectives and disciplines. 

Defining Safety

In the simplest terms, safety can 

be defined as the absence of risk 

or danger. Focusing this term to 

address transportation, road safety 

can be characterized by the ability 

of a person to travel freely without 

injury or death. A perfectly safe 

transportation system would not 

experience crashes between various 

road users. Though absence of all 

crashes is an optimal condition, and 

many transportation agencies have 

a goal of zero deaths on the road, 

the reality is that people continue 

to get injured or killed on streets 

and highways across the nation. The 

challenge posed to the road safety 

field is to minimize the frequency 

of crashes and the resulting deaths 

and injuries using all currently 

available tools, knowledge, and 

technology. This challenge is made 

more complex due to the multitude 

of factors influencing safety, from 

infrastructure to vehicle design to 

human behavior. 

Road safety professionals typically 

measure safety by the number and 

rate of crashes and by the severity 

of those crashes. Crash frequency, or 

the number of crashes occurring per 

year or other unit of time, is another 

commonly used metric. Crash rates

are numbers of crashes normalized 

by a particular population or metric 

of exposure. Commonly cited crash 

rates include crashes per 100,000 

people living in a particular State, 

city or country. Some crash rates 

present crash numbers per miles 

traveled or licensed drivers. Crash 

outcomes can be measured by 

the types of injuries sustained to 

the people involved in the crash, 

typically categorized by fatalities 

and injury severity. Focusing on 

crashes that result in severe injuries 

and fatalities is one strategy that 

agencies use to prioritize their 

safety activities.

In addition to the measures 

described above, safety professionals 

can use surrogate measures, such as 

Crash 

frequency

The number 

of crashes 

occurring per 

year or other 

unit of time.

Crash rate

The number 

of crashes 

normalized by 

a particular 

population 

or metric of 

exposure.

Crash 

outcome

Measured 

by the types 

of injuries 

sustained to the 

people involved 

in the crash.

1966

3,500

billion Vehicle Miles Traveled (billions)

Fatality Rate per 100 Million 

Vehicle Miles Traveled

6

5

4

3

2

1

3,000

2,000

1,000

1976198619962006

FIGURE 1-3: Fatality Rate and Vehicle Miles Traveled, 1966-2013 (Source: NHTSA FARS)
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-3

Nominal 

safety

An absolute 

statement 

about the safety 

of a location 

based only on 

its adherence 

to a particular 

set of design 

standards and 

related criteria.

Substantive 

safety

Historical and 

long-term 

objective safety 

of a location 

based on 

crash data.

conflicts (near misses), avoidance 

maneuvers, and the time to collision 

if no evasive action is taken, to 

determine the level of safety risk 

and identify specific problems. 

Safety problems may exist even 

in locations that do not have a 

demonstrated history of crashes, 

just as someone who smokes is at 

higher risk for lung cancer even if 

no cancer has yet been detected. 

This can be especially true for 

non-motorized road user safety, 

such as pedestrians and bicyclists, 

since crashes involving these 

road users may be infrequent and 

appear random at first sight. In 

such locations where crashes are 

sparse or distributed across the 

system, safety professionals can use 

surrogate measures to fill the gaps 

and assess the road’s level of risk. 

Observing traffic at an intersection, 

for example, may reveal a pattern 

of near misses and other conflicts 

between vehicles and pedestrians. 

This pattern may not appear in 

crash data, but can be a valuable 

source of information to highlight 

the potential for safety risk. 

Safety perception is also an 

important consideration for travel 

choices. There are a number of 

reasons why someone may or may 

not choose a particular route to 

drive, walk or bike. Pedestrians who 

perceive an intersection to be unsafe 

may cross in a midblock location, 

where they are more easily able to 

find a gap in traffic. Motorists may 

feel uneasy about making a left turn 

across multiple lanes of traffic, so 

they may choose to turn right and 

travel out of their way to perform 

a U-turn instead. Safety perception 

impacts road user decisions but is 

not easily understood by looking 

at crash data. Safety professionals 

can use surveys, driving simulators, 

and other modern technologies to 

understand the safety perception of 

road users.

Evaluating the safety of a particular 

network, corridor or intersection 

requires an understanding of both 

nominal and substantive safety. 

Originally introduced by Dr. Ezra 

Hauer,3

 these terms offer a helpful 

framework for assessing the safety 

of a particular location. Decades of 

research and evaluation in the field 

of road safety have revealed a wealth 

of knowledge concerning the proper 

designs and policies that contribute 

to the safety of a particular location. 

Roadways constructed according to 

the best and latest recommended 

research and design standards are 

said to be nominally safe. Nominal 

safety is an absolute statement 

about the safety of a location based 

only on its adherence to a particular 

set of design standards and related 

criteria. A road that was nominally 

safe when it was first opened to 

traffic may become nominally 

unsafe when the roadway design 

standards change, even though 

the road’s crash performance has 

not changed.

While nominal safety considers 

the design of a road, it does not 

incorporate any information about 

the frequency, type and severity of 

crashes occurring on the facility. The 

historical and long-term objective 

safety of a location based on crash 

data is known as substantive safety. 

A particular intersection that has 

experienced fewer than expected 

crashes over an extended period 

will be referred to as a substantively 

safe location, while a corridor with 

a higher than expected number of 

crashes is substantively unsafe. 

Hauer, E. 

Observational 

Before/After Studies 

in Road Safety. 

Estimating the Effect 

of Highway and 

Traffic Engineering 

Measures on Road 

Safety. Pergamon 

Press. 1997.

3
1-4 UNIT 

1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

Unlike nominal safety, substantive 

safety operates on a continuum and 

allows for a range of explanations 

as to why a particular safety 

problem exists. 

Another key distinction is the fact 

that a location can be nominally 

safe – adhering to all standards and 

design criteria – while experiencing 

high rates of crashes, making it 

substantively unsafe. Similarly, a 

substantively safe location (one that 

has a lower than expected crash 

rate) may be nominally unsafe if it 

does not meet the applicable design 

standards. 

Agencies and safety professionals 

should strive to prioritize the 

substantive safety of a facility. 

Simply building a road that meets all 

the current design standards will not 

ensure that the road is substantively 

safe. Using professional judgement 

to prioritize safety improvements 

and select appropriate designs 

within a range of options, based on 

observations of road user behavior 

and other available data, will 

increase the chance that all factors 

are considered. The end result will 

be a road that moves a step closer 

to the ultimate goal of having 

a transportation system free of 

injuries and deaths.

Road Safety Decisions 

and Trade-offs

The goal of improving safety 

exists alongside other goals of the 

transportation system, such as 

mobility, efficient movement of 

people and goods, environmental 

concerns, public health, and 

economic goals. In this way, 

transportation professionals and 

policy makers often refer to 

trade-offs – making a decision to 

favor one goal at the expense of 

another. While those in the field of 

road safety continually look for 

new designs and technologies to 

advance all goals, there continue 

to be many instances where public 

agencies must weigh competing 

goals for a location or portion of 

the road network and decide what 

trade-offs should be made for the 

goal of increasing road safety. 

Below are several examples: J Roundabouts: A city may decide 

to install a roundabout at an 

intersection to decrease the 

potential conflicts between 

various movements at the 

intersection. Safety is improved, 

especially related to left-turns, 

since all turns are now part of the 

circle. However, a roundabout 

does require traffic on the main 

road to slow their speeds and 

navigate through the roundabout. 

During heavy traffic, especially 

Design Dimensions

(LANE WIDTH, RADIUS OF CURVE, 

STOPPING SIGHT DISTANCE, ETC.)

Crash Risk

Nominal 

Safety

Substantive

Safety

FIGURE 1-4: Comparison of nominal 

and substantive concepts of safety http://

safety.fhwa.dot.gov/geometric/pubs/miti-

gationstrategies/chapter1/1_comparnom-

inal.cfm (Source: NCHRP Report 480, 

Transportation Research Board, 2002)
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-5

if it is unbalanced among the 

intersection legs, this may 

cause a decrease in the overall 

throughput of the intersection. 

However, this is a trade-off to 

produce fewer crashes.

J Bicycle Helmet Requirements: 

In order to improve bicyclist 

safety, some jurisdictions have 

adopted ordinances that require 

bicyclists to wear helmets. In 

practice, this can reduce the risk 

of head injuries among cyclists, 

but it may also reduce the 

number of people who choose 

to ride a bicycle. Adopting such 

ordinances would prioritize 

safety while potentially reducing 

bicycle ridership.

J Red Light Cameras: Red light 

camera enforcement monitors 

signalized intersections and 

records information about 

those who violate red light 

laws, typically resulting in 

citations through the mail. These 

cameras have been shown to 

improve safety by decreasing 

the types of crashes that result 

in serious injury,4

 but installing 

the cameras can be met with 

significant public opposition. 

J Protected Left Turns: To 

minimize the risk of severe 

left-turn crashes at signalized 

intersections, engineers may 

choose to provide left turning 

drivers an exclusive protected 

left turn phase (green arrow). 

While this minimizes crash risk 

by separating the left turning 

vehicles from other movements, 

it also requires that extra time 

be added specifically for left 

Council, et al. 

Safety Evaluation of 

Red-Light Cameras. 

Federal Highway 

Administration. 

April 2005. https://

www.fhwa.dot.

gov/publications/

research/safety/

05048/05048.pdf 

4
1-6 UNIT 

1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

turns, which can increase delay 

for the rest of the traffic at the 

intersection.

J Rumble Strips: In rural locations, 

rumble strips can be installed as 

a measure to alert drivers when 

they are running off the road. 

However, these rumble strips are 

usually installed on the edge of 

the road or the paved shoulder 

where bicyclists can safely and 

comfortably ride separated 

from traffic. This may result 

in bicyclists riding in the road 

where they are more vulnerable 

to crashes with motor vehicles.

J Trees and Landscaping:

Street trees, shrubs, and 

other vegetation can serve a 

valuable purpose in roadside 

environments – particularly 

creating shade for the sidewalk, 

serving as a buffer between the 

road and sidewalk area, and 

even creating “visual friction” 

that can keep vehicle speeds 

down. However, trees can also 

pose a safety risk for vehicles 

that run off the road and collide 

with them. Vegetation that is 

too close to an intersection 

can restrict sight distance, 

contributing to crashes. Selected 

tree and vegetation removal is an 

excellent example of a 

trade-off between safety and 

other beneficial features of trees.

J Traffic Signal Installation: A 

high-speed, high-volume road 

with multiple traffic lanes may 

separate housing developments 

from an elementary school. In 

order for children living in the 

housing development to safely 

travel to and from school, a 

traffic signal and crosswalk may 

be installed along the busy road. 

Motorists will be delayed since 

they are required to stop for a 

period of time while the students 

cross, but the crossing is safer 

for those students.

J Access Management: Left turns 

in and out of shopping centers, 

especially along multilane roads, 

can result in severe injuries to 

motorists when crashes occur. 

Eliminating these left turns by 

building raised median islands 

and consolidating driveways 
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-7

J LIST various ways to measure the safety 

of a road and describe the advantages 

and disadvantages of each. Consider factors such as the type of information each 

safety measure provides as well as other 

issues such as how it can be collected.

J DESCRIBE a change that could be made 

to a road or intersection that would 

improve one transportation goal (e.g., 

traffic operations, public health, mobility and access, environmental quality, or 

economic growth) at the expense of the 

safety of road users.

J DESCRIBE a change that could be made 

to a road or intersection that would 

improve road safety at the expense of 

another transportation goal (e.g., traffic 

operations, public health, mobility and 

access, environmental quality, or economic growth).

J DESCRIBE a change that could be 

made to a road or intersection that 

would improve safety for a road user 

but not at the expense of other users, 

or other goals.

EXERCISES

can eliminate these risky 

movements; however, this 

prevents direct access to the 

stores by potential customers.

Sometimes improving safety 

for one group of road users may 

negatively impact the safety of 

another group. It can also be the 

case that improving mobility for a 

group of road users may negatively 

affect the safety of that same group. 

There is no absolutely correct 

answer to many of these trade-offs, 

as they are all context-specific. 

Transportation professionals need to 

discuss the various trade-offs in the 

context of a particular community’s 

transportation goals. These types of 

trade-offs are made every day, and 

require the cooperation of numerous 

agencies and stakeholders, all 

of whom have a role to play in 

transportation decision-making. 

Despite the temptation to study road 

safety as a self-contained system, 

there are a multitude of factors 

influencing and being influenced by 

road safety and travel behavior. In 

order to make informed decisions 

about the transportation system, 

transportation professionals 

must understand the impacts – 

both positive and negative – that 

design, operations, and policy 

decisions have on the safety of 

the transportation network as 

well as the impacts on other areas 

such as public health, mobility, 

environmental quality, and 

economic growth. 
1-8 UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

Road Safety Through the Years

CHAPTER 2 FOUNDATIONS OF ROAD SAFETY

When examining current efforts to 

address road safety, it is useful to 

view them in the context of American 

transportation history. Recent 

decades have witnessed numerous 

advances in the field of road safety. 

This growing national consciousness 

about the need for safer roads 

provides a stark contrast to the first 

half of the twentieth century when 

the focus was on highway expansion. 

The following chapter will provide 

an overview of the major milestones 

and achievements that led to the 

transportation system we have today, 

as well as the policies and practices 

that were implemented to address a 

growing safety problem.

Late Nineteenth Century and 

the Popularity of Bicycling

An exploration of the history of 

road safety in the U.S. can begin at 

many different points – some of 

our roads were developed as precolonial routes and others were 

trails blazed by Native Americans. 

In terms of lasting influence on the 

modern transportation network, 

however, it is most useful to begin 

the discussion in the late nineteenth 

century. 

In the 1880s and 1890s, bicycles 

were the dominant vehicle on 

our nation’s roads. With the 

introduction of the “safety” bicycle, 

with two wheels of the same size, 

and the pneumatic tire in the late 

1880s, the bicycling craze became an 

economic, political, and social force 

in the U.S. By 1890, the U.S. was 

manufacturing more than 1 million 

bicycles each year.

At that time, bicyclist behavior—

particularly careless or risk-taking 

behavior—was a contributing 

factor to bicycle crashes. However, 

the biggest contributor to crashes 

existed outside the cities; the poor 

condition of the nation’s roads made 

cycling a laborious and dangerous 

process. Bicycle groups worked 

at the Federal, State, and local 

levels to secure road improvement 

legislation. The work of these 

advocacy groups became known as 

the Good Roads Movement.

Three men 

with bicycles 

on bridge near 

Pierce Mill, 

Washington, 

D.C., 1885. 

(Source: 

Brady-Handy 

Collection, 

U.S. Library

 of Congress)
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-9

To build support, advocates tailored 

their message to farmers with 

the argument that bad roads, 

by increasing transportation 

expenditures, cost more than good 

roads. While engineers, writers, and 

politicians joined the movement, 

bicyclists dominated the Good Roads 

Movement until cars arrived in the 

early twentieth century.5

By the close of century, automobiles 

had slowly begun to share the roads 

with bicyclists and pedestrians, 

benefitting from many of the road 

improvement efforts spearheaded 

by cycling groups. In 1899, a motor 

vehicle struck and killed a New 

York City pedestrian. This event 

marked the first time in the U.S. 

that a person was killed in a crash 

involving a motor vehicle.6

 

Rise of Motor Vehicles in the 

Early Twentieth Century

In 1905, only 78,000 automobiles, 

most of which were confined to the 

cities, traveled the U.S. Ten years 

later, 2.33 million automobiles were 

traveling the country’s roads, and by 

1918, this number had increased to 

5.55 million. Mass production made 

this increase possible as it lowered 

vehicle manufacturing costs, putting 

vehicles within the reach of the 

middle class. As more vehicles 

became available at a lower price, 

the pattern of daily travel in the U.S. 

began to shift. Longer vehicle trips 

replaced shorter trips by foot or 

bicycle, and development patterns 

began to follow suit. The motor age 

had arrived, and with it a new kind 

of highway would evolve, designed 

specifically for motor vehicles.

Expansion of automobile use had 

immediate positive effects on the 

national economy and quality of life 

around the country. Yet proliferation 

of motor vehicles also had a negative 

side. As millions of new drivers 

took to the roads, traffic crashes 

increased rapidly—tripling from 

10,723 in 1918 to 31,215 in 1929.7

 

Consequences of Speeding

As in modern times, in the early days of the 

automobile, posted speed limits were set 

far below the speed of which most motor 

vehicles were capable.

With faster and heavier traffic, it became 

dangerous to drive in the middle of 

the road and the States began painting 

centerlines on the pavements to channel 

traffic in lanes. At 40 miles per hour, these 

lanes appeared uncomfortably narrow to 

most motorists, especially when passing 

trucks. The lane lines also caused trucks 

to run closer to the shoulder, causing the 

slab edges and corners of the road to 

break. To provide greater safety and 

reduce edge damage, State highway 

departments built wider pavements 

and made new roads straighter. 

These improvements along with mechanical

advances in vehicles, such as more 

powerful engines and four-wheel brakes, 

in turn encouraged even faster speeds. 

Thus, after 1918, highway design followed 

a spiral of cause and effect, resulting in 

faster and faster speeds and wider and 

wider pavements. The motivating force 

behind this spiral was the driving speed 

preferences of the great mass of vehicle 

operators. The public authorities were 

never able to impose or enforce speed 

limits for very long if the majority of drivers 

considered the limits unreasonably low. 

Now, many current engineering practices 

use the 85th percentile speed – or the 

speed at which the majority of drivers travel 

– as the method of setting speed limits.

Source: Richard 

F. Weingroff, “A 

Peaceful Campaign 

of Progress and 

Reform: The 

Federal Highway 

Administration at 

100,” Public Roads 

57, no. 2 (Autumn, 

1993), http://www.

fhwa.dot.gov/

publications/

publicroads/93fall/

p93au1.cfm

Soniak, Matt. When 

and Where Was the 

First Car Accident? 

Mental Floss. 

2 December 2012. 

http://mentalfloss.

com/article/31807/

when-and-wherewas-first-caraccident

Source: America’s 

Highways, 1776-1976: 

A History of the 

Federal-Aid Program. 

Federal Highway 

Administration 

(U.S. Government 

Printing Office, 

Washington D.C., 

1976).

5

6

7
1-10 UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

Shifting Attention to Safety

Recognizing the rise in crashes and 

resulting injuries and fatalities, 

Secretary of Commerce Herbert 

Hoover convened the First 

National Conference on Street and 

Highway Safety in Washington, 

D.C., in December 1924. Here, for 

the first time, representatives of 

State highway and motor vehicle 

commissions, law enforcement, 

insurance companies, automobile 

associations and a multitude of other 

stakeholders and interest groups 

met in one place to discuss how 

to address the growing number of 

fatalities and serious injuries.

Prior to the conference, committees 

were established to perform 

research into areas such as planning 

and zoning, traffic control, motor 

vehicles, statistics, and other 

areas related to road safety. 

These committees reported wide 

differences in traffic regulations 

from State to State and city to city. 

For instance, twenty States did not 

attempt to collect crash statistics, 

only eight States required reporting 

crashes that resulted in personal 

injury, and 38 required railroads 

and common carriers to report 

highway crashes. Other committees 

devoted their attention to issues like 

traffic control and vehicle speeds, 

infrastructure and maintenance 

concerns, and issues impacting 

vehicles and their drivers. 

Conference participants supported 

a wide range of measures to 

reduce the rate of crashes and 

recommended that legislative, 

administrative, technical, and 

educational bodies adopt them. 

Conference participants also 

recommended that the States take 

the lead by passing adequate motor 

vehicle laws and setting up suitable 

agencies for administering the laws, 

policing the highways, registering 

vehicles, and licensing drivers. 

To the Federal Government, the 

conference assigned the role of 

encouragement, assembly and 

distribution of information, 

and the development of 

recommended practices. Adoption 

and implementation of these 

recommended practices would be 

left to the individual States.

Secretary of Commerce Herbert Hoover, center, with President Calvin Coolidge, right, 

in February 1924. (Source: Harris & Ewing Collection, U.S. Library of Congress)
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-11

Secretary Hoover called a second 

conference for March 1926. During 

the interim between the two 

conferences, a special committee 

drew up a model “Uniform Vehicle 

Code” covering registration and 

titling of vehicles, licensing of 

drivers, and operation of vehicles on 

the highways. The code incorporated 

the best features of the numerous 

and varied State laws then on 

the statute books. The second 

conference approved this code 

and recommended it to the State 

legislatures as the basis for uniform 

motor vehicle legislation.

Studies following this 1926 

conference concluded that 

determining the causes of crashes 

was far more difficult than they had 

presumed. The problem warranted 

a sustained program of research 

by a national organization. The 

Conference agreed, and the Highway 

Research Board (HRB) organized 

the Committee on Causes and 

Prevention of Highway Accidents 

to coordinate crash research 

nationwide. The HRB played a major 

part in subsequent efforts to reduce 

the consequences of crashes.8

Federal Government Role 

in Highway Development

The growing use of motor vehicles 

during the 1920s was mirrored 

by the expansion of the Federal 

Government’s role in funding and 

building roads. In its early form, the 

Office of Public Roads was organized 

under the U.S. Department of 

Agriculture, playing a large role in 

funding roadways within national 

parks and forests. 

Following the Federal Aid Road Act 

of 1916, this office would become 

the Bureau of Public Roads (BPR), 

charged with working cooperatively 

with State highway departments on 

road projects. Work continued on 

the expansion of highways across 

the country, and between 1921 and 

1939, the distance of paved roads 

Balanced Design for Safety

In the 1920s and 1930s, it was good 

engineering practice to design new 

highways as much as possible in long 

straight lines or “tangents.” When it 

became necessary to change direction, 

the engineer laid out a circular curve, 

the radius of which he selected to fit 

the ground with the least construction 

cost, but which could not be less than a 

certain minimum fixed by department 

policy. In practice, engineers made the 

curves sharper than this minimum when 

it was cheaper to do so, but with little 

consistency. Engineers expected motorists 

driving these roads to adjust their speeds 

to the varying radii, and on the sharper 

curves safe design speed might be 

considerably lower than the posted 

speed limit.

Increasing concern for road safety led many 

highway engineers to worry about this 

inconsistency between posted speed limits 

and safe design speed on curves. In 1935, 

highway engineer Joseph Barnett of the BPR 

proposed that all new rural roads conform to 

an “assumed design speed,” a comfortable 

top speed for drivers outside of urban areas. 

With its adoption by American Association 

of State Highway Officials in 1938, Barnett’s 

“balanced design” concept became a 

permanent feature of U.S. roadway design. 

Today, standards for designing curves, 

such as design speed, curve radius and 

superelevation (the tilt of the road through 

a curve) are provided in A Policy on 

Geometric Design of Highways and Streets, 

produced by the American Association for 

State Highway Transportation Officials.

Source: America’s 

Highways, 1776-1976: 

A History of the 

Federal-Aid Program. 

Federal Highway 

Administration 

(U.S. Government 

Printing Office, 

Washington D.C., 

1976).

8

Uniform 

Vehicle Code

A code covering 

registration and 

titling of vehicles, 

licensing of 

drivers, and 

operation of 

vehicles on 

the highways.
1-12 UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

increased from 387,000 miles to 

nearly 1.4 million miles.9

 The BPR 

recognized that the antiquated 

highway system was one of the 

contributing causes of the high 

crash toll, but did not go so far as 

to identify primary crash causes or 

recommend potential solutions.

During this time, an emphasis was 

placed on expanding the Federal 

role in the process of highway 

design and development. This 

effort culminated in 1944 when 

Congress approved the development 

of a National System of Interstate 

Highways along with that year’s 

Federal Aid Highway Act. Though 

expansive in scope, calling for a 

40,000 mile network, the legislation 

was not accompanied by any funds 

to support the development of 

these highways. Without funding, 

the legislation did not significantly 

expand the highway system.

Road safety continued to present 

a national concern. In May 1946, 

President Harry S. Truman spoke at 

the Highway Safety Conference to 

rally public support to improve State 

motor vehicle laws, driver licensing, 

and education. After summarizing 

his unsuccessful efforts as a U.S. 

senator to enact Federal legislation 

on motor vehicle registration and 

driver licensing, the President 

said Congress was not yet ready to 

interfere with what many perceived 

as State prerogatives. However, he 

noted that the Federal Government 

would not stand aside if the rates of 

highway fatalities continued to rise.10 

Source: Weingroff, 

Richard. A Peaceful 

Campaign Of 

Progress And Reform: 

The Federal Highway 

Administration 

at 100. Public 

Roads Magazine. 

Vol. 57 No. 2. July 

1993. http://www.

fhwa.dot.gov/

publications/

publicroads/93fall/

p93au1.cfm

Source: Richard 

F. Weingroff and 

the assistance of 

Sonquela Seabron, 

President Dwight 

D. Eisenhower and 

the Federal Role 

in Highway Safety, 

accessed May 23, 

2013, http://www.

fhwa.dot.gov/

infrastructure/

safetyin.cfm

9

10

Safety Signs

Before World War I, most States were 

using signs to warn road users of danger 

ahead, particularly at railroad crossings; 

railroad companies themselves were 

required to post warning signs at all public 

road crossings. However, there was little 

agreement between States about the 

specific design of these warning devices, 

and the signs were a variety of shapes, 

sizes, and colors.

In 1929, the American Engineering Council 

surveyed sign practices in all U.S. cities 

with a population of more than 50,000 

and created a document that was, in 

effect, a manual of the best practices 

of the time. Recognizing the need for 

standard practices for signs in rural and 

urban areas, the American Association of 

State Highway Officials and the National 

Conference on Street and Highway 

Safety organized a Joint Committee on 

Uniform Traffic Control Devices in 1931 

and introduced a new manual for national 

use in 1935. The manual of best practices 

changed over time to become the Manual 

on Uniform Traffic Control Devices. 

President Harry S. Truman, 1945. 

(Source: U.S. Library of Congress)
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-13

Post War Development 

and Growth

Economic conditions following 

World War II led to even higher 

levels of driving and automobile 

ownership. Personal savings of 

almost $44 billion created a market 

for housing and other types of 

goods, chief among them new 

automobiles. Automobile production 

jumped from a nearly 70,000 in 1945 

to 3.9 million in 1948.

Because of this increase in 

vehicle production, motor vehicle 

registrations spiked and the number 

of drivers on the nation’s roads and 

highways reached unprecedented 

levels. Under wartime rationing of 

rubber, and specifically tires, States 

had implemented speed controls to 

reduce wear and tear and improve 

tire longevity. With the end of 

rationing and emergency speed 

controls at the conclusion of the 

war, highway travel returned to 

pre-war levels and began a steady 

climb of about 6 percent per year, 

which would continue for nearly 

three decades.

While the increasing popularity of 

low density housing development 

(i.e., the suburbs) and the 

availability of motor vehicles created 

perfect conditions for more driving, 

the nation’s roads and highways 

were unprepared for the increase in 

traffic. Under wartime restrictions, 

States were unable to adequately 

maintain their highways. With 

widespread operation of overloaded 

trucks and reduced maintenance, 

the State highway systems were in 

worse structural shape post-war 

than before the war.

Development of the Interstate 

Highway System

Though the National System of 

Interstate Highways had been 

established by legislation in 

1944, little progress was made 

over the next decade. Without 

funding, established routes were 

slow to develop. That changed in 

1956, when President Dwight D. 

Eisenhower signed the FederalAid Highway Act of 1956. This 

legislation linked the development 

of the interstate highway system to 

the interest of national defense and 

assigned funding that would rapidly 

expand the highway network.11 The 

act established a dedicated funding 

stream and a plan for highway 

development that launched the 

nation into an unprecedented era of 

expansion in which new interstate 

corridors linked cities and towns to 

one another.

http://www.

fhwa.dot.gov/

publications/

publicroads/

06jan/01.cfm

11

President 

Dwight D. 

Eisenhower 

speaks to the 

White House 

Conference on 

Highway Safety, 

1954. (Source: 

Eisenhower 

Presidential 

Library)
1-14 UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

Despite the enthusiasm of political 

and business leaders, the growth 

of this system was not without 

its critics. These critics primarily 

denounced the destruction of homes 

and separation of communities 

that sometimes resulted from new 

highways bisecting established 

neighborhoods. Though this opposition 

halted projects in some locations, 

it did not stop the expansion of the 

interstate highway system. 

Highway Safety Act of 1966

In 1964, the U.S. faced a sharp rise 

in the number of traffic fatalities. 

An increased number of vehicles 

on the roadways combined with a 

public culture that did not prioritize 

roadway safety consciousness led 

to 47,700 deaths on the nation’s 

highways, an increase of 10 percent 

over the number of fatalities that 

occurred in 1963. These deaths 

prompted the nation to take a hard 

look at road safety efforts and 

resulted in Congressional hearings in 

March 1965 to raise public awareness 

of the growing national crisis.12

To respond to these trends, the 

nation needed a change of direction 

in the design and operation of its 

roads and vehicles. This change 

began with reviewing safety 

standards in these areas and 

conducting research to identify 

effective measures to improve 

safety. The 1960s was a pivotal 

decade for road safety due to the 

passage of laws that provided 

funding and new policies. On 

September 9, 1966, President 

Lyndon B. Johnson signed the 

National Traffic and Motor Vehicle 

Safety Act of 1966 and the Highway 

Safety Act of 1966. The signing 

ceremony in the Rose Garden 

of the White House marked a 

transformation in the role of the 

Federal Government in road safety. 

This role had been growing during 

the Eisenhower administration, but 

became a larger area of emphasis as 

fatalities on the nation’s highways 

climbed toward 50,000. Those in 

the federal government observed 

that the steps taken during the 

previous two decades to reverse the 

climbing number of fatalities had 

failed, and they believed that road 

safety should no longer be left solely 

to the responsibility of the States, 

the automobile industry, and the 

individual drivers.13

This legislation established the 

U.S. Department of Transportation 

(USDOT) and transformed the 

Bureau of Public Roads into the 

Federal Highway Administration 

(FHWA). New bureaus were added to 

address safety in areas of growing 

concern, such as the Bureau of 

Motor Carrier Safety and National 

Highway Safety Bureau (these 

would later become the Federal 

Motor Carrier Safety Administration 

and the National Highway Traffic 

Safety Administration, respectively). 

The USDOT proceeded to develop 

programs and initiatives and 

pave the way for activities still in 

place today.14

Advances in vehicle design 

and policy were also an area of 

emphasis during the 1960s. In 

1968, federal legislation required 

vehicles to provide seat belts. 15 

Federal law also required States to 

begin implementing motorcycle 

helmet laws in order to qualify for 

particular sources of funding.16 

These requirements led to more 

widespread implementation of 

safety policies through the late 

Source: Richard 

F. Weingroff and 

the assistance of 

Sonquela Seabron, 

President Dwight 

D. Eisenhower and 

the Federal Role 

in Highway Safety, 

accessed May 23, 

2013, http://www.

fhwa.dot.gov/

infrastructure/

safetyin.cfm

12 13

http://www.

fhwa.dot.gov/

infrastructure/

50interstate.cfm

Federal Motor 

Vehicle Safety 

Standard (FMVSS) 

No. 218, 

https://www.federal

register.gov/

documents/2015/05/

21/2015-11756/

federal-motorvehicle-safetystandardsmotorcycle-helmets

Title 49 of the 

United States Code, 

Chapter 301, Motor 

Vehicle Safety, 

https://www.gpo.

gov/fdsys/pkg/

USCODE-2009-

title49/html/

USCODE-2009-

title49-subtitleVI.

htm

14

16

15
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-15

1960s and 1970s. Section 402 of 

the Highway Safety Act established 

a revenue stream for funding to 

directly support State programs 

aimed at improving road safety. 

Known as the State and Community 

Highway Safety Grant Program, the 

funds originally supported a variety 

of program areas, including many 

many behavioral safety programs 

that are still in existence today. 17

Energy Crises and Safety 

Legislation in the 1970s 

and 1980s

The 1970s and 1980s were 

characterized by energy crises in 

1973 and 1979 that had immediate 

and lasting impacts on travel trends. 

Vehicle Miles Traveled (VMT) 

decreased following each of these 

events, as Americans drove less 

due to rising fuel costs. Strategic 

legislative action by Congress, such 

as the National Maximum Speed 

Law of 1974 which prohibited speeds 

higher than 55 miles per hour also 

helped by decreasing fuel costs. The 

law would later be repealed in 1995, 

allowing States to set their own 

maximum speed limits.

Between 1970 and 2007, there 

were two periods of time when 

VMT decreased from the previous 

year. These years include 1974 and 

1979, each of which saw a roughly 

18 billion mile decrease in VMT 

from the previous year.18 As driving 

decreased, so did traffic fatalities. 

From 1973 to 1974, for example, 

traffic fatalities went down 16 

percent – the largest single year 

decline since 1941-1942.19 Driving 

levels began to increase again 

once fuel costs normalized, so 

the reductions were not sustained 

beyond the period of economic 

stagnation.

The Highway Safety Act of 1973 

established a specific methodology 

for improving roadway safety from 

an engineering perspective. It 

required the States to first survey 

all hazardous locations and examine 

http://www.

fhwa.dot.gov/

policyinformation/

travel_monitoring/

tvt.cfm

Governors Highway 

Safety Association. 

Section 402 State 

and Community 

Highway Safety 

Grant Program. 

http://www.ghsa.

org/about/federalgrant-programs/402

18

17

https://crashstats.

nhtsa.dot.gov/Api/

Public/ViewPub

lication/811346

19

President Lyndon B. Johnson signs the National Traffic and Motor Vehicle Safety Act of 

1966 and the Highway Safety Act of 1966. (Source: LBJ Presidential Library)
1-16 UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

the causes of crashes at these sites. 

A benefit/cost analysis was then 

performed to prioritize needed 

improvements. This process set 

the stage for the current safety 

management processes and would be 

refined and improved over the years. 

The Highway Safety Act of 1973 also 

clarified the relationship between 

the Federal Government and the 

States. The Federal Government 

was to direct policy and program 

components, while the States were 

responsible for implementing those 

policies and programs.20

During the 1970s, Congress also 

established the Motor Carrier Safety 

Assistance Program (MCSAP). 

This program provides financial 

assistance to States to reduce the 

number and severity of crashes 

and hazardous materials incidents 

involving commercial motor 

vehicles (CMV) through inspection 

and enforcement programs 

focused on trucks, carriers, 

and driver regulations. 21

Vehicle safety continued to be a 

priority in the 1970s and 1980s, as 

more States began to implement 

laws requiring the use of seat belts 

and motorcycle helmets. New York 

became the first State to adopt a 

mandatory seat belt law in 1984, and 

other States soon followed suit.22 

The Federal Motor Vehicle Safety 

Standard 213 brought attention 

to child passenger safety. This 

standard was the first to outline 

specific requirements for restraint 

systems designed for children. 

Multimodal Shift in the 1990s

The 1990s saw a shift from 

transportation policies that focused 

on motor vehicle safety and 

efficiency to an acknowledgement of 

alternate modes of transportation, 

such as bicycling, walking and use 

of public transit. The Intermodal 

Surface Transportation Efficiency 

Act of 1991 (ISTEA) added a 

multimodal perspective to the 

Federal-aid highway program. 

While ISTEA was not specifically 

focused on transportation safety, it 

created some programs to promote 

safer travel. For example, ISTEA 

enhanced road safety with new 

programs that encouraged the 

use of safety belts and motorcycle 

helmets.23 The legislation also 

required the installation of airbags 

for drivers and front passengers in 

all cars and trucks.24

In 1998, the Transportation Equity 

Act for the 21st Century (TEA-21) 

provided more focus for roadway 

safety planning by establishing 

safety and security as planning 

http://www.iihs.org/

iihs/topics/laws/

safetybeltuse

22

Source: “What is 

the Motor Carrier 

Safety Assistance 

Program (MCSAP)?” 

accessed May 23, 

2013, https://www.

federalregister.gov/

documents/2000/03/

21/00-6819/motorcarrier-safetyassistance-program

21

Source: “HSIP 

History,” accessed 

October 22, 2013, 

http://safety.fhwa.

dot.gov/hsip/gen_

info/hsip_history.cfm 

and “Subchapter J—

Highway Safety: Part

924—Highway Safety 

Improvement Program,” 

accessed October 

21, 2013, http://www.

gpo.gov/fdsys/pkg/CFR2003-title23-vol1/pdf/

CFR-2003-title23-vol1-

chapI-subchapJ.pdf.

20

Source: 

“Intermodal Surface 

Transportation 

Efficiency Act of 1991 

Information,” last 

updated May 16, 2013, 

accessed July 05, 2013, 

http://www.fhwa.

dot.gov/planning/

public_involvement/

archive/legislation/

istea.cfm.

23

1893Office of Road Inquiry is created, 

which would eventually become the 

Federal Highway Administration

1908Ford Model T is released as 

the first automobile available 

to most of the middle class 1916Bureau of 

Public Roads 

is created

1924First national conference 

on highway safety held 

in Washington, DC 1926Uniform Vehicle Code is 

developed during the second 

highway safety conference 1932Revenue Act of 1932 

establishes first national 

gas tax at 1 cent per gallon

ROAD SAFETY TIMELINE

See next page.

24
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-17

http://www.history.

com/this-day-inhistory/federallegislation-makesairbags-mandatory

24

priorities. Prior to TEA-21, a State or 

Metropolitan Planning Organization 

(MPO) may have incorporated 

safety in its goals or long-range 

transportation plan, but specific 

strategies to increase safety were 

seldom included in statewide and 

metropolitan planning processes 

or documents.

TEA-21 established the Highway 

Safety Infrastructure program (not 

to be confused with the Highway 

Safety Improvement Program, 

which would be developed several 

years later), which funded safety 

improvement projects to eliminate 

safety problems. 

The TEA-21 legislation also 

encouraged States to adopt and 

implement effective programs to 

improve the quality (e.g. timeliness, 

accuracy, completeness, uniformity 

and accessibility) of State data 

needed to identify safety priorities 

for national, State and local road 

safety programs.25

Not to be lost among the TEA-21 

legislation, another pivotal moment 

in transportation legislation came in 

2000 when an important provision 

related to alcohol was included in 

the USDOT appropriation act. The 

appropriation carried a requirement 

that all States must enact laws to 

limit the legal blood alcohol content

(BAC) of drivers to 0.08 percent.26 

This limit was in line with similar 

limits imposed on drivers in other 

countries, though some European 

countries limit the legal BAC to 0.05 

percent. 

While 19 States and Washington, 

D.C., had already enacted this law, 

the Federal mandate provided a 

further incentive for other States 

to do so: States that did not pass 

the law by 2004 would forego a 

portion of their transportation 

funding. Though specific laws vary, 

each State now recognizes the legal 

limit of 0.08 percent blood alcohol 

content.27

http://www.ghsa.org/

html/stateinfo/laws/

impaired_laws.html

27

Rodriguez-Iglesias, 

C.; Wiliszowski, ClH.; 

Lacey, J.H. Legislative 

History of .08 Per 

Se Laws, National 

Highway Traffic Safety 

Administration, 

Report No. DOT HS 

809 286, June 2001

26

Source: “TEA-21 

– Transportation 

Equity Act for the 21st 

Century Fact Sheets,” 

last modified April 5, 

2011, accessed June 

2, 2013, http://www.

fhwa.dot.gov/tea21/

factsheets/index.htm

25

Blood alcohol 

content

The percentage 

of alcohol in 

a person’s 

blood, used to 

measure driver 

intoxication.

1944Congress approves the 

development of the National 

System of Interstate Highways 1956Federal-Aid Highway Act provides 

dedicated funding stream to support 

the interstate highway system 1966Highway Safety Act and National Traffic and 

Motor Vehicle Safety Acts are signed, creating 

the U.S. Department of Transportation 1968First Federal Motor Vehicle 

Safety Standard requiring 

seat belts is passed

1971First Federal safety 

standard requiring child 

passenger restraints

Officers use specialized devices to 

measure drivers’ blood alcohol content.
1-18 UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

Legislation in the 21st Century

Twenty-first century legislation 

continued to move Federal 

transportation funding and 

policy in the direction of focusing 

on multimodal, data-driven 

approaches to improving the 

transportation system. One specific 

area of focus was a move toward 

safety planning. Transportation 

safety planning shifts the focus 

of traditional planning efforts to 

a more comprehensive process 

that integrates safety into 

transportation decision-making. 

Safety planning encompasses 

corridors and entire transportation 

networks at the local, regional, 

and State levels, as well as 

specific sites.28

In 2005, Congress passed the Safe, 

Accountable, Flexible, and Efficient 

Transportation Equity Act—A 

Legacy for Users (SAFETEA-LU). 

SAFETEA-LU raised the stature of 

Federal road safety programs by 

establishing the Highway Safety 

Improvement Program (HSIP) as 

a core Federal-aid program tied 

to strategic safety planning and 

performance. HSIP is one of six 

core Federal-aid programs under 

which funds are apportioned 

directly to the States. One of the 

major elements of the HSIP was 

Source: 

“Transportation 

Safety Planning 

(TSP),” accessed 

August 13, 2013, 

http://safety.fhwa.

dot.gov/hsip/tsp/ 

and “Transportation 

Safety Planning Fact 

Sheet,” accessed 

August 13, 2013, 

http://safety.fhwa.

dot.gov/hsip/tsp/

fact_sheet.cfm.

Title 23 United 

States Code § 148

28

29

1973Oil embargo leads to energy crisis

Highway Safety Act of 1973, 

introduction of National 

Maximum Speed Law 1979Oil crisis in the 

wake of the 

Iranian Revolution

1974Safety standard 

requiring motorcycle 

helmets is passed

1998TEA-21 is passed, along with a call for 

all States to adopt a 0.08 percent 

blood alcohol content limit for drivers 2012MAP-21 

is passed

1984New York becomes first 

State to pass mandatory 

seat belt law

1993Gas tax 

increased to 18.4 

cents per gallon 1995National 

Maximum Speed 

Law is repealed

2005SAFETEALU is 

1991

passed

ISTEA is 

passed

the requirement for each State to 

develop and implement a Strategic 

Highway Safety Plan (SHSP).29

The plans sought to establish 

data-driven approaches that were 

coordinated with a broad range of 

stakeholders and utilized a diverse 

set of disciplines (e.g., engineering, 

enforcement, education and 

emergency response). These datadriven plans had to include clear 

methods for measuring progress 

toward safety goals.

The Moving Ahead for Progress in 

the 21st Century Act (MAP-21) was 

signed into law in 2012. The 2012 

legislation transformed the policy 

and programmatic framework 

for investments in the country’s 

transportation infrastructure, 

enhancing the programs and policies 

established in 1991.

MAP-21 doubled funding for road 

safety improvement projects, 

strengthened the linkage among 

modal safety programs and created a 

positive agenda to make significant 

progress in reducing highway 

fatalities and serious injuries. It 

provided increased focus on the 

importance of high quality data, 

transportation infrastructure and 

the safety of local streets. 
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-19

U.S. Department 

of Transportation. 

Strategic Plans. 

November 2015. 

https://www.

transportation.gov/

mission/budget/

dot-budget-andperformancedocuments#

StrategicPlans

30

J RESEARCH a federal transportation law 

addressed in this chapter and write a 

summary about the law, emphasizing 

the safety aspects. 

J FIND a recent news article that involves 

road safety (more than just a local news 

article on a recent crash) and write a 

summary describing the effort undertaken by the public agency, how it was 

received by the public, and whether it 

was shown to be effective in increasing 

road safety.

J USE https://www.govtrack.us to find a 

transportation bill currently proposed 

or under review by Congress. Describe 

how the legislation would be expected 

to affect road safety. 

J RESEARCH the legal driving Blood 

Alcohol Content (BAC) by state in the 

U.S. and create a table showing the 

comparison. Select one state where 

the legal BAC is lower than the federal 

requirement, locate a paper or news 

article describing how that BAC level 

was decided, and write a summary.

EXERCISES

Conclusion

Exploring the history of travel 

trends and safety in the U.S. helps 

illustrate how past decisions have 

led to the transportation system 

seen today. Safety has not always 

been a deciding factor in how roads 

are built. However, today, safety 

is a top priority of the USDOT.30

Most State and local transportation 

agencies share USDOT’s goal; 

some have even set goals to reduce 

total traffic fatalities to zero. 

These “vision zero” and “toward 

zero deaths” goals are guiding 

transportation projects by requiring 

safety to be incorporated into every 

step of project planning, design, 

construction and operation. 

Future safety issues will certainly 

arise as technological advancements 

lead to changes in the vehicle 

fleet. Autonomous and potentially 

driverless vehicles are being 

developed and tested across the 

world. Though safety improvements 

are touted as a benefit of these 

advanced vehicles, safety will 

continue to be a priority as they 

begin to share the roads with older 

vehicles, bicyclists, and pedestrians. 

As can be learned from the history 

of road safety in the U.S., complex 

problems must be met with safety 

advancements, legislative action, 

and collaboration.
1-20 UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

Road safety is a complex issue, and 

any efforts to improve safety must 

address not only the roadway but 

also road user behavior, vehicle 

design, interaction between 

road users, and the effect of the 

roadway on all road users. Road 

safety partners include anyone 

who influences road user safety, 

including those in infrastructure 

safety, behavioral roadway safety, 

transportation planning, public 

health, public safety and many other 

disciplines. Each of these disciplines 

is able to provide a unique 

perspective and each has specific 

methods for addressing road safety. 

It is becoming increasingly common 

for these various disciplines to work 

in collaboration with one another 

to address road safety through 

comprehensive programs. Instead 

of focusing on traditional “silos” 

of activity, agencies hope that this 

interaction and collaboration among 

various disciplines will lead to 

continued safety improvements.

This chapter will discuss 

road safety efforts from the 

disciplines of roadway design and 

engineering, public education, 

and enforcement campaigns. 

Working in collaboration with one 

another, as described above, these 

groups can share the burden of 

road safety responsibilities and 

create comprehensive programs to 

address the various factors that may 

contribute to crashes. 

Multidisciplinary Approaches

CHAPTER 3 FOUNDATIONS OF ROAD SAFETY

The E’s

A popular multidisciplinary approach to 

road safety is sometimes referred to as 

the “four E’s”: Engineering, Education, 

Enforcement, and Emergency response. 

These E’s broadly represent the 

various disciplines that bring together 

stakeholders who care about making 

the road safe for all users. Sometimes 

a fifth “E” for evaluation is added to 

this list to represent the important 

role of evaluating what works and what 

doesn’t. This emphasizes the fact that 

good data is crucial to the improvement 

of road safety.
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-21

Roadway Design 

and Engineering

Several types of transportation 

professionals are responsible for 

roadway safety engineering. 

Broadly speaking, the roadway 

safety engineering community 

includes transportation planners 

and engineers. 

Transportation planning plays a 

critical role in determining the shape 

of the transportation system and 

provides an early opportunity for 

professionals to address safety needs. 

Before a road project is designed or 

built, it is influenced by any number 

of comprehensive and strategic 

transportation plans that are 

coordinated to ensure that the system 

being developed is one that matches 

the vision of the local community. 

Planners work with stakeholders 

such as the general public, business 

owners, policy makers, and 

advocates to establish plans for how 

the transportation system can best 

serve every group’s needs. 

In the past, the traditional planning 

process focused on economic 

development, environmental quality, 

and mobility as the three primary 

concerns. Most States consider 

infrastructure safety improvements as 

part of preservation or improvements 

projects or within operational 

changes undertaken by traffic 

offices. States are now able to use 

the Highway Safety Improvement 

Program (HSIP) to fund safety 

projects in at high priority locations. 

This program allows development 

of targeted solutions and approaches 

that address the contributing 

factors to collisions, thereby 

seeking to achieve a higher return 

on safety investments. 

Roadway engineers work on the 

design, construction and system 

preservation of the roadways. In 

particular, engineers are charged 

with designing roads that minimize 

the chance that crashes will occur 

while balancing the needs for 

efficiency and mobility. Engineers 

also work to design roads and 

intersection in such a way that 

minimizes crash severity and 

injury risk when crashes do occur. 

Engineers affect the safety of the 

built environment by incorporating 

safety in to the planning process at 

the beginning of a project; selecting 

design alternatives that prioritize 

safety considerations; using 

design elements that maximize 

the safety of each part of the road 

or intersection; ensuring quality 

and safe construction, operation, 

and maintenance of the roads; 

and addressing safety problems at 

existing locations.

Infrastructure improvements such 

as paved shoulders, rumble strips, 

and improved nighttime visibility 

may prevent drivers from veering 

off the roadway, and still other 

opportunities exist for improving 

the roadside and road user behavior. 

For example, when a driver veers 

off the roadway, it is important to 

provide a roadside environment that 

reduces the potential for crashes and 

injury. Roadside slopes and objects 

such as drainage structures, trees, 

and utility poles are examples of 

roadside elements that engineers 

can target for improvements to 

road safety performance. One 

engineering method to increase 

roadside safety is to create a clear 

zone—an unobstructed, traversable 

roadside area that allows a driver to 

stop safely or regain control of the 

vehicle that has left the roadway.
1-22 UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

Engineering solutions must 

incorporate the different needs 

and preferences of a variety of user 

groups. As mentioned previously, 

this often means that tough 

decisions and trade-offs must be 

made to arrive at infrastructure 

solutions that balance the needs of 

different users. This trade-off can 

be illustrated with an example of a 

signalized intersection. Improving 

intersection safety for pedestrians 

may involve adding pedestrian 

crossing time to the signal or 

separating turn movements to 

eliminate high risk conflicts. 

Protected left-turn phases can 

also improve safety for vehicles, as 

shown previously. But these new 

or longer signal phases either add 

time to the cycle length or keep 

the same length while reducing 

time for the through movements. 

Regardless, the result is more delay 

to both pedestrians and motorists. 

In such situations, it is necessary 

to consider all of these needs and 

select the appropriate signal timing 

that meets the needs of all users. 

Adhering to design standards – 

creating nominally safe conditions 

– is only one aspect of the complex 

roadway design and engineering 

field. Addressing substantive safety 

through design strategies requires 

an understanding of multiple 

perspectives, trade-offs and 

user needs.

Public Education and 

Enforcement Campaigns

Public education and communications 

campaigns are commonly used 

to improve road user attitudes 

and awareness. The structure 

and delivery methods of these 

campaigns can take many forms. 

However, they generally involve 

materials (media advertisements, 

informational brochures, posters, 

presentations, etc.) to inform 

people of a desired behavior and 

the benefits of such behavior (or 

conversely, the risks of an unwanted 

behavior).

While standalone informational or 

educational campaigns can improve 

awareness or perceptions about road 

safety issues, they are unlikely to 

change road user behavior. Rather, 

campaigns that educate the public 

about increased law enforcement 

efforts aimed at a particular 

behavior have been shown to be 

effective. Generally referred to as 

“high-visibility enforcement” these 

campaigns increase the perceived 

enforcement of a particular law. 

When people believe there is a high 

probability of being caught, they are 

more likely to follow the law. The 

Click it or Ticket campaign is one of 

the most widely known examples 

of high-visibility enforcement. 

In this case, simply enforcing the 

seatbelt law was not sufficient. 

The key to this program’s success 

was the media coverage and other 

informational campaigns telling the 

public that law enforcement officers 

are looking for people who are not 

wearing a seatbelt. In other words, 

for those people who do not typically 

wear a seatbelt, the law itself 

was not sufficient motivation to 

change. The motivation came from a 

Countermeasures That Work

Countermeasures That Work31 is a 

comprehensive guidance document 

providing details of different programs 

and interventions that are effective 

in improving safety. The guide is 

published regularly by NHTSA. 

Countermeasures 

that Work: A 

Highway safety 

Countermeasures 

Guide for State 

Highway Safety 

Offices, 7th edition, 

2013 DOT HS 811 727

31
ROAD SAFETY FUNDAMENTALS UNIT 

1: FOUNDATIONS OF ROAD SAFETY

1-23

perceived threat of being caught and 

ticketed.

When safety professionals analyze 

possible educational campaigns, they 

must consider the factors that affect 

people’s behavior and the probability 

that the campaign will change such 

behavior. Simply communicating 

safety messages and enforcing 

laws may not lead to a change in 

behavior if a road is designed in a 

way that allows (or unintentionally 

encourages) unsafe behaviors. For 

example, to address a speeding 

problem on a wide multilane 

arterial where the posted speed is 

35 miles per hour, enforcement 

and education may not be the only 

solution. Narrowing the roadway 

and creating more “visual friction” 

along the roadside may be needed 

to alter the desired design speed of 

the road. Supplemental education 

and enforcement campaigns can 

then help reinforce the proper 

behavior. This emphasizes the need 

for cooperation and coordination 

between disciplines to accomplish 

Targeted Enforcement

To reinforce pedestrian safety laws, 

police departments can initiate targeted 

enforcement operations at crosswalks. 

Under this approach, a law enforcement 

officer in plain clothes will attempt 

to cross the street at an uncontrolled 

crosswalk. Drivers who do not yield 

to the officer will be pulled over and 

either cited or warned by patrol vehicles 

waiting beyond the crosswalk. More 

info: http://www.nhtsa.gov/staticfiles/

nti/pdf/812059-PedestrianSafetyEnforce

OperaHowToGuide.pdf
1-24 UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

meaningful improvements to 

road safety.

While there is evidence to suggest 

some success for well-designed and 

executed safety education campaigns 

when they are targeted at children,32 

the same results have not been 

shown for teens and adults when 

an educational campaign stands 

alone. Though well-intentioned, 

these approaches generally assume 

that people are not performing 

the desired behavior simply 

because they lack the appropriate 

information. However, this idea fails 

to take into account the fact that, 

in general, most human behavior is 

not the result of conscious, rational 

deliberation. People are largely 

influenced by emotions, values, 

social context, and culture, among 

many other factors. Thus, simply 

being presented with information 

or facts alone is unlikely to lead to 

any lasting behavior change. In the 

context of transportation safety, 

most people do not engage in risky 

or undesirable behaviors due to a 

lack of knowledge about the desired 

behavior. Instead, people act based 

on a variety of contributing factors. 

For example, consider the behavior 

of a pedestrian on a multi-lane 

undivided arterial. The goal of 

the pedestrian is to get to a bus 

stop located directly across the 

street from his current location. 

The pedestrian almost certainly 

knows that the desired behavior 

is to walk a quarter mile to the 

signalized intersection, wait and 

cross with the crossing signal, and 

then to backtrack a quarter mile to 

the bus station. However, instead 

the pedestrian chooses to cross in 

the middle of the block. The fact 

is that there are many factors that 

influence the pedestrian’s decision 

to cross mid-block (time, ability, 

weather, etc.), but likely the most 

important factor is that doing so 

just makes sense. People are wired 

to choose the option that makes 

the most intuitive sense. Efforts to 

change this behavior only through 

signs, posters or other educational 

campaigns will likely have only 

minimal effect.

Similar examples can be found 

throughout the transportation safety 

field. Most people already know they 

should wear their seatbelt, obey 

posted speed limit signs, and limit 

distractions while driving. Yet some 

people refuse to wear a seatbelt, 

Bicycle Safer Journey

Bicycle Safer Journey is an educational 

program intended to provide bicycle 

safety skills and education to children. 

The program uses interactive video 

lessons to teach children safe bicycling 

skills and provides resources for 

parents and teachers. The program 

can be accessed online at http://www.

pedbikeinfo.org/bicyclesaferjourney. 

Zegeer, C. V., 

Blomberg, R. D., 

Henderson, D., 

Masten, S. V., 

Marchetti, L., 

Levy, M. M., Fan, 

Y., Sandt, L. S., 

Brown, A., Stutts, 

J., & Thomas, L. J. 

(2008b). Evaluation 

of Miami–Dade 

pedestrian safety 

demonstration 

project. 

Transportation 

Research Record 

2073, 1-10.

32
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-25

some people speed, and some people 

text while driving. Knowledge alone 

is not enough.

Successful education and 

enforcement campaigns recognize 

the reality of people’s behaviors and 

apply this knowledge to the safety 

efforts. For example, social norms 

and cultural influences can provide 

some explanation for why certain 

behaviors are common - even those 

behaviors known to be unsafe. 

Marketing interventions based on 

social norms have been applied 

to the areas of distracted driving 

and driving under the influence of 

alcohol. Such methods provide a 

way to examine safety problems and 

Media Campaign Effectiveness

Well planned and executed media 

campaigns centered on reducing 

alcohol-impaired driving can be 

effective in reducing the occurrence of 

alcohol related crashes. A study in 2004 

pointed to a 13 percent decrease in 

alcohol related crashes following these 

types of campaigns.33

Click It or Ticket

Click It or Ticket is a successful seat belt 

enforcement campaign that has helped to 

increase the national seat belt usage rate. 

The program uses public education to 

communicate the law and risks of not 

using seat belts in a variety of settings. 

The campaigns provide waves of education 

and enforcement along with high visibility 

media coverage to publicize and sustain 

the campaign. NHTSA manages this 

campaign annually with assistance from 

the State Highway Safety offices, law 

enforcement agencies, and national- and 

local-paid advertising.

Elder, R.W., et 

al. Effectiveness 

of mass media 

campaigns for 

reducing drinking 

and driving and 

alcohol-involved 

crashes: a 

systematic review. 

July 2004. http://

www.sciencedirect.

com/science/

article/pii/

S0749379704000467

33
1-26 UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

what might be done to address them 

through education and enforcement. 

Comprehensive 

Safety Programs

While each discipline has its own 

strengths, significant improvements 

in roadway safety are more likely 

when a program encompasses 

many disciplines rather than 

just one. Interdisciplinary team 

efforts can take on safety problems 

using multiple approaches and 

are therefore greater in scope 

than individual disciplines 

working in isolation. The need 

for this “multiple approach” 

solution requires collaboration 

among many parties. This type of 

collaboration is most clearly seen 

when agencies seek to create a 

comprehensive safety plan. Creating 

a comprehensive safety plan for 

a city, county, or state must be a 

data driven process. In doing so, 

agencies first begin by analyzing 

their safety data to identify 

emphasis areas where concentrated 

efforts are likely to yield the largest 

reduction in fatalities and serious 

injuries. 

A State’s Strategic Highway Safety 

Plan (SHSP) is an example of a 

comprehensive safety plan, and one 

of the best examples of a multidisciplinary, data driven planning 

effort. A State SHSP provides 

a framework for developing a 

coordinated and comprehensive 

approach to addressing road safety 

across a State. In the development of 

a State’s SHSP, safety stakeholders 

from across the State and across 

disciplines will consider all the 

data available (i.e., crash, injury 

surveillance, roadway and traffic, 

vehicle, enforcement, and driver 

data) that will help an agency 

understand where more safety 

emphasis is needed.34 Beyond crash 

records, an agency may choose to 

rely on alternate data sources like 

roadway characteristics and its own 

knowledge of crash risk to pursue 

systemic safety strategies. A systemic 

approach proactively identifies 

locations that may have a high risk 

of crashes but where the risk has 

not yet resulted in actual crashes.35

Strategic 

Highway 

Safety Plan

Provides a 

framework for 

developing a 

coordinated and 

comprehensive 

approach to 

addressing road 

safety across 

a State.

https://safety.

fhwa.dot.gov/shsp/

guidebook/

34

http://safety.fhwa.

dot.gov/systemic

35
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-27

Demographic data showing where 

population growth has occurred, 

or where it is expected, can also 

influence an agency’s safety plans. 

One of the most critical components 

of the SHSP is an evaluation of past 

efforts, so that the agency can know 

what strategies are working and so 

that progress toward goals can be 

measured and tracked over time.

Road safety planning, like the field of 

safety itself, is multidisciplinary in 

nature and relies upon the expertise 

and involvement of numerous 

perspectives. Once developed, these 

safety plans influence activities 

ranging from roadway design and 

engineering to law enforcement and 

safety education. 

Each of the agencies and 

organizations involved in 

transportation safety brings a unique 

and valuable perspective to bear on 

the roadway safety problem. Their 

competing philosophies, worldviews 

and problem solving approaches, 

however, can make collaboration 

difficult. Creating a foundation 

for effective collaboration and 

establishing a process to support 

collaborative efforts are two ways 

to overcome these barriers. One 

way to create a foundation for 

collaboration is to ensure that each 

agency understands the impact 

that its actions have on road safety 

and that each makes safety its top 

priority. The example of a State 

Strategic Highway Safety Plan shows 

this type of collaboration. The SHSP 

process brings together all potential 

areas of safety emphasis, including 

intersections, non-motorized 

users, rural crashes, and others, 

and uses a data driven approach 

to identify priorities and areas 

of need. This foundation can be 

further strengthened by identifying 

which agencies or organizations are 

responsible for implementing each of 

the strategies identified in the SHSP. 

In the U.S., no single player manages 

all programs and disciplines that 

impact road safety. Therefore, 

collaboration among all players is 

fundamental to consistently reduce 

serious injuries and fatalities.

J FIND the website for your State or 

local road safety program. Identify 

initiatives that your State or local 

agency is implementing in the areas of 

planning, engineering, education, and 

enforcement.

J CONSIDER a hypothetical situation 

where it is your job to convene a team 

of professionals to visit a high crash 

intersection and explore possible 

solutions to the safety problem. Create 

a list of the people who should be 

included on that team and briefly 

describe each person’s role. Be sure to 

consider the many different types of 

programs and strategies that can be 

used to improve road safety. 

J SELECT an area of concern, either a 

specific type of road user or an unsafe 

behavior, and discuss how road safety 

in this topic area could be addressed or 

improved through multiple disciplines. 

Possible topics include:

J Older drivers

J Underage drinking

J Fatigued or drowsy driving

J Pedestrians

EXERCISES
1-28 UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

Drivers of motor vehicles are far 

from the only users of the road, 

despite accounting for the majority 

of trips taken in the U.S. The public 

right-of-way on most roads is 

usually shared by a number of 

different users, traveling by a 

variety of modes for any number of 

different reasons. Transportation 

professionals must understand 

the mobility and safety needs of 

different user groups and how 

they interact with one another to 

gain a better understanding of 

safety problems and their 

potential solutions.

Road user groups include:

J Passenger vehicle drivers 

and occupants

J Drivers of trucks 

and other large vehicles

J Motorcyclists

J Pedestrians

J Bicyclists

Passenger Vehicle Drivers 

and Occupants

Passenger vehicles are typically 

defined as sedans, pickup trucks, 

minivans, and sport utility vehicles 

and represent the primary mode 

of transportation for the majority 

of Americans. Since these vehicles 

account for the vast majority of 

registered vehicles and vehicle 

miles traveled, it is not surprising 

that much of the transportation 

infrastructure prioritizes the needs 

of these drivers. 

However, despite the priority given 

to drivers of passenger vehicle, 

there remain many unresolved 

safety issues for these drivers. At 

the core of most of these issues are 

the driver’s actions while navigating 

the road network. Engineers may 

work to make a road nominally 

safe by ensuring it follows the 

latest recommendations and design 

standards. However, drivers do not 

always interact with the road system 

as road designers expect them to. 

Thus, a nominally safe road may 

be much less safe in a substantive 

sense. While the common reaction 

has been to assume that some 

fault or “driver error” led to the 

crash, this approach fails to take 

into account a common behavioral 

principle known as behavioral 

adaptation. Simply put, behavioral 

adaptation refers to the unconscious 

process by which people react to 

their environment -- people cannot 

be considered to be a constant in 

the system.

Consider a town that wants to 

resurface and widen a two-lane 

collector roadway through an 

older neighborhood with mature 

street trees. The existing road has 

9.5 foot wide lanes, a 30 mi/h (48 

ki/h) speed limit, and street trees 

between the roadway and sidewalk. 

Design guidance may suggest a 

typical lane width of 12 feet and a 

wider roadside clear zone. It is easy 

to assume that the safest choice 

would be to design a road with the 

widest lanes possible and removal 

Road Users

CHAPTER 4 FOUNDATIONS OF ROAD SAFETY
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-29

of the roadside hazards. However, 

after this resurfacing and widening 

project was completed, both traffic 

speeds and crash severity along this 

roadway may increase considerably. 

On the surface, this may seem 

counterintuitive.

In essence, most people drive at 

a speed that feels safe to them. 

To reach this “safe speed,” 

people unconsciously assess the 

roadway and its characteristics. 

Navigating a narrow, curvy road 

with significant roadside hazards is 

more challenging than navigating a 

straight, wide road with large clear 

zones, so people unconsciously 

drive slower and more cautiously on 

the narrow road. When the driving 

task is made easier by widening 

the lanes and removing roadside 

hazards, people will not maintain 

their original behavior. In fact, 

the assumption should be that 

people will adapt to this change 

and unconsciously change their 

behavior accordingly, in this case by 

increasing their speed.

Behavioral adaptation is not 

specific to passenger vehicles. 

When designing the transportation 

infrastructure, engineers must 

consider how human behavior plays 

affects all roadway users. Roadway 

designers must design roads not 

for the way in which they would 

like users to behave, but for the 

way in which users actually behave. 

Behavior of drivers and other road 

users will be covered in a greater 

detail in Unit 2.

The intended speed of this road is 35 miles per hour, but the wide design of the road and 

the number of lanes leads drivers to drive much faster.
1-30 UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

Drivers of Trucks and 

Other Large Vehicles

Much of the transportation 

network across the country serves 

an important commercial need. 

Truck drivers, in particular, play 

a significant role in the national 

economy and are responsible for 

moving goods between and within 

cities and States. Large trucks 

account for only 4 percent of 

registered vehicles in the U.S., but 

they make up 9 percent of total 

vehicle miles traveled and accounted 

for 12 percent of total traffic fatalities 

in 2013.36 These large trucks share 

space on the roads with passenger 

vehicles, and have their own safety 

needs. Nationally in 2013, there were 

just under 4,000 people killed in 

crashes involving large trucks, and 

71 percent of them were occupants 

of the other vehicle involved in the 

crash. However, large truck safety 

has improved over time. Between 

2004 and 2013, the miles covered by 

large trucks increased by roughly 25 

percent, while fatalities involving 

large trucks decreased by about 20 

percent (from 4,902 to 3,906).37

Commercial trucks are not the 

only large vehicles on the roads. 

Transit vehicles occupy space on 

our roadways as well, though they 

typically serve pedestrians and 

bicyclists. Transit vehicles that share 

space with passenger vehicles also 

have unique needs and challenges. 

Many of the safety issues associated 

with transit vehicles are similar to 

those of large trucks. Bus operators 

have to consider how stopping 

in traffic impacts the flow and 

operation of the transportation 

system, and must also consider the 

safety of their passengers boarding 

and disembarking the vehicle.

Road designs that accommodate 

large vehicles can sometimes be 

directly at odds with designs that 

favor pedestrians and bicyclists. 

For example, a pedestrian is 

more comfortable crossing an 

intersection if the turns are very 

tight, where the distance between 

corners in minimized to shorten 

the walking distance and decrease 

the time in the roadway. Large 

trucks and buses, however, require 

a larger turning radius (when 

compared to passenger vehicles) 

in order to turn safely. When 

designing intersections for large 

trucks, designers are tempted to 

increase the amount of space in an 

intersection and widen the corners. 

This change will make the turn 

easier, but it will also be more 

uncomfortable (and possibly less 

safe) for pedestrians. As described 

previously, these trade-offs need 

to be assessed and discussed when 

planning road projects.

Motorcyclists

In recent years, motorcycling 

has become increasingly popular 

throughout the U.S. Since 2000 the 

number of registered motorcycles 

in the U.S. has nearly doubled. 38 39 

The result was a 71% increase in 

the number of motorcyclist 

fatalities (from 2,897 in 2000 

to 4,957 in 2012). Motorcyclists 

represented 15 percent of all traffic 

fatalities in 2012, compared to 

just 7 percent of fatalities in 2000. 

40 Motorcyclists are significantly 

overrepresented in traffic fatalities 

since they account for only 

3 percent of registered vehicles 

and 0.7 percent of total vehicle 

miles traveled in 2012.41

http://www-nrd.

nhtsa.dot.gov/

Pubs/812150.pdf

http://www.

fhwa.dot.gov/

policyinformation/

statistics/2013/pdf/

mv1.pdf

https://www.fhwa.

dot.gov/ohim/hs00/

pdf/mv1.pdf

http://www-fars.

nhtsa.dot.gov/

Main/index.aspx

http://www-nrd.

nhtsa.dot.gov/

Pubs/812035.pdf

36

38

39

40

41

37
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-31

In general, many of the roadway 

modifications done to improve 

safety for passenger vehicles can 

pose a challenge for motorcyclists. 

Rumble strips can be difficult to 

traverse, especially at low speeds. 

Guard rails, in particular cable 

barriers, can present a serious 

hazard to a motorcyclist impacting 

one at a high speed. Within the 

driving environment, motorcyclists 

are small compared to larger 

vehicles and can be difficult to see, 

especially early or late in the day 

when lighting levels are lower. 

Pedestrians

Walking is the most basic form 

of transportation. At some point 

during a typical day, nearly every 

person is a pedestrian. People walk 

to get to a bus station, to go from 

home to school, or to get from a 

parked vehicle to the front door 

of a business. Some walking trips 

are taken out of necessity – not 

all households own a vehicle, 42

and children and individuals with 

disabilities may not have the option 

to drive. Many more walking trips 

are taken by choice, especially for 

exercise or health. A 2012 survey 

found that 39 percent of trips taken 

by foot are done for exercise or 

personal health purposes. 43 Walking 

is also more common in densely 

populated urban areas, due to the 

close proximity of destinations and 

other services like transit stations.

Regardless of the reasons for 

walking, this mode accounts for 

nearly 11 percent of all trips taken 

in the U.S., according to the 2009 

National Household Travel Survey 

(NHTS). 44 The NHTS shows that 

about a third of all trips taken in 

the U.S. are shorter than one mile, 

and 35 percent of these trips are 

taken by foot. In the 2005 Traveler 

Opinion and Perception Survey 

(TOP), conducted by FHWA, data 

showed that about 107.4 million 

Americans (51 percent of the 

traveling public) use walking as a 

regular mode of travel. 45

Pedestrians (along with bicyclists) 

are among the most vulnerable road 

users, and this is reflected in crash 

data. The 4,743 pedestrians killed 

in 2012 represented 14.1 percent 

of total traffic fatalities in the U.S. 

that year. Between 2008 and 2012, 

motor vehicle fatalities decreased 13 

percent, while pedestrian fatalities 

increased 8 percent. Within the 

population of pedestrians, there 

are certain groups which are 

especially vulnerable. These include 

young children, older adults, and 

individuals with disabilities. 

https://info.ornl.gov/

sites/publications/

Files/Pub50854.pdf

http://www.

pedbikeinfo.org/

data/factsheet_

general.cfm

http://www.

pedbikeinfo.org/

cms/downloads/15-

year_report.pdf

http://www.fhwa.

dot.gov/reports/

traveleropinions/

1.htm

42

43

44

45
1-32 UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

Road Diet

In 2008, Seattle Department of 

Transportation implemented a road diet 

on a 1.2-mile (1.9-kilometer) section of 

Stone Way North from N 34th Street to N 

50th Street. In addition to serving motor 

vehicles, this segment of Stone Way North 

helps connect a bicycle path with a park. 

Within five blocks are eight schools, two 

libraries, and five parks.

The modified segment was originally 

a four-lane roadway carrying 13,000 

vehicles per day. For this corridor, 

the city’s 2007 bicycle master plan 

recommended climbing lanes and shared 

lane markings (previously known as 

“sharrows”). The cross section reduced 

the number of travel lanes to add bicycle 

lanes and parking on both sides. The 

resulting corridor saw a decrease in the 

85th percentile speed, while the overall 

capacity remained relatively unchanged 

despite the reduction in the number 

of lanes. The number of bicyclists on 

the corridor increased by 35 percent, 

but crashes involving bicyclists did not 

increase. Pedestrian crashes declined by 

80 percent following the project.

Summarized from a 2011 Public Roads 

article: http://www.fhwa.dot.gov/publications/

publicroads/11septoct/05.cfm

Before (left) and after (right) pictures of Stone Way North. (Source: Seattle DOT)

Young children are a vulnerable 

road user group, and may be more 

likely than adults to rely on walking 

as a primary transportation mode 

– especially before they are old 

enough to drive. One area of concern 

is creating a safe environment for 

young children when they walk to 

school. Safety professionals need 

to ensure that sidewalks and street 

crossings have the appropriate 

measures to assist children in 

traveling safely, and educate 

children about safe walking.

Another vulnerable portion of the 

pedestrian population includes 

those who are blind or visually 

impaired. These pedestrians have 

increased challenges in navigating 

the road safely, particularly at 

street crossings. Challenges faced 

by a blind or visually impaired 

pedestrian include finding the 

appropriate crossing point at an 

intersection corner or midblock 

location, determining the appropriate 

time to cross, and crossing quickly 

and accurately. Both crossing and 

traversing a sloped sidewalk can be 

equally difficult for an individual in a 

wheelchair, where even slight cracks 

or bumps in the sidewalk can present 

major obstacles. The difficulties of 

these challenges increase at locations 
ROAD SAFETY FUNDAMENTALS UNIT 1: FOUNDATIONS OF ROAD SAFETY 1-33

with unusual geometry, irregularly 

timed signals, or non-stop vehicle 

flow such as roundabouts and 

channelized turn lanes.

Older adults face many challenges 

as well. There are a number of 

age-related changes that affect the 

functional ability of older adults 

to safely walk and cross the street. 

These changes include diminished 

physical capability, sensory 

perception, cognitive skills and lag 

in reflexive responses. Eyesight 

deterioration can diminish an older 

person’s ability to see and read 

guide signs, slow their reaction time 

and decrease their ability to gauge 

a vehicle’s approaching speed or 

proximity. 46

Drivers and pedestrians share 

responsibility for many pedestrian 

fatalities, as both parties attempt 

to navigate through the same 

space at the same time. Though 

we know that certain factors are 

likely to result in more severe 

pedestrian crashes, such as speed 

47, no single cause stands out as 

the major contributor to pedestrian 

crashes. For this reason, no single 

countermeasure alone would likely 

make a substantial impact on the 

number of pedestrian crashes. A 

successful countermeasure program 

should use a mix of engineering, 

environmental, educational and 

enforcement measures to improve 

pedestrian safety. 48

Source: “Identifying 

Countermeasure 

Strategies to 

Increase Safety to 

Older Pedestrians,” 

National Highway 

Traffic Safety 

Administration, 1.

https://www.

aaafoundation.org/

sites/default/files/

2011Pedestrian

RiskVsSpeed.pdf

Source: “Identifying 

Countermeasure 

Strategies to 

Increase Safety to 

Older Pedestrians,” 

National Highway 

Traffic Safety 

Administration, 36

46

47

48
1-34 UNIT 1: FOUNDATIONS OF ROAD SAFETY ROAD SAFETY FUNDAMENTALS

Bicyclists

Bicyclists were some of the first 

users of U.S. roads, and the group 

that made the earliest push to 

improve road conditions. In recent 

years, bicycling has seen a rise in 

popularity for both recreation 

and transportation. Data from 

the 2009 NHTS showed that while 

only 1 percent of all trips are 

taken by bicycle, the number of 

bicycle trips doubled between 

1990 and 2009.49 

While bicyclists account for only 1 

percent of all trips, the 726 bicyclist 

fatalities in 2012 represented 2 

percent of all traffic fatalities 

that year.50 While the number of 

bicyclists killed has risen only 

slightly since 2008, the decline in 

motor vehicle deaths means that 

bicyclists account for an increasing 

share of total traffic fatalities.

Bicyclists face unique challenges 

as road users. More often than not, 

bicyclists share space with motor 

vehicles and are considered legal 

users of the road in most locations. 

Many potential bicycle riders are 

not comfortable sharing the road 

with heavy vehicular traffic and 

may be deterred from riding their 

bicycles. Intersections can also 

pose a challenge to bicycle riders 

when they include high volumes 

of turning traffic and a large 

number of lanes. These barriers 

to bicycling, busy street segments 

and intersections, often discourage 

potential riders even when the rest 

of a bicycle network is comfortable. 

Many bicyclists are willing to go out 

of their way to use a route that has 

lower vehicle volumes and speeds, or 

bicycle facilities that are separated 

from traffic. Safe bicycle facilities 

can also improve connections to 

shopping, transit, jobs, schools, and 

essential services.

Conclusion

Successful road safety programs 

will consider the needs of all users 

when planning and developing 

transportation projects. Each user 

group plays an important role in 

the transportation system, and 

each has unique safety needs that 

safety professionals must consider. 

Road user decisions are influenced 

by a variety of factors, and the 

combinations of factors that result 

in particular travel behavior cannot 

easily be categorized or understood 

in simple terms.

J PROVIDE an example of a road 

project where the changes resulted in 

improvements for one user group, but 

negatively impacted another group. This 

example could be hypothetical or based 

on a real world experience.

J VISIT the Fatality Analysis Reporting 

System (FARS) Encyclopedia home page 

(http://www-fars.nhtsa.dot.gov/Main/

index.aspx). Use the data available 

for the most recent year to document 

fatality numbers for the different road 

user groups discussed in this chapter 

(e.g. motorists, pedestrians, bicyclists). 

What other information on road user 

safety can you find with the tools 

available in FARS, and what data is 

not included?

EXERCISES

http://www-nrd.

nhtsa.dot.gov/

Pubs/812018.pdf

50

http://www.

pedbikeinfo.org/

cms/downloads/

15-year_report.pdf

49

FHWA, Office of Safety

Felix H. Delgado, P.E.

Felix.Delgado@dot.gov

FHWA-SA-18-003

Road Safety Fundamentals is available for free at: 

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