LOMA LINDA UNIVERSITY

School of Public Health

_______________________________

EFFECTS OF ROAD DIETS ON PEDESTRIAN AND CYCLIST INJURIES

IN LOS ANGELES

By

Donna L. Gurule

_______________________________

A Dissertation Proposal in Partial Fulfillment of the Requirements for the

Degree of Doctor of Public Health in Health Policy and Leadership

May 19, 2016

© 2016

Donna L. Gurule

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Each person whose signature appears below certifies that this dissertation, in his

or her opinion, is adequate in the scope and quality as a dissertation for the degree of

Doctor of Public Health.

________________________________________

Ed McField, PhD, Co-Chair Associate Professor, Health Policy and Leadership Loma Linda University, School of Public Health ________________________________________

Helen Hopp Marshak, PhD, MCHES, Co-Chair Dean, School of Public Health

________________________________________

Jisoo Oh, DrPH, Member Assistant Professor, Health Policy and Leadership Loma Linda University, School of Public Health

________________________________________

Samuel Soret, PhD, MPH, Member Executive Director, Center for Community Resilience Associate Dean for Research Loma Linda University, School of Public Health

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________________________________________

James Martinez, EdD, MPH, Member

Assistant Professor

Loma Linda University, School of Public Health

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ABSTRACT OF THE DISSERTATION PROPOSAL

Effects of Road Diets on Pedestrian and Cyclist Injuries in Los Angeles

By

Donna L. Gurule

Doctor of Health Policy and Leadership

Loma Linda University, 2016

Ed McField, PhD, Chair

Helen Hopp Marshak, PhD, MCHES, Co-Chair

Background. The way communities are designed influences the amount of

physical activity people can acquire each day. In the U.S., communities are designed

around vehicles and research shows that this type of design leads to lower rates of

physical activity and higher rates of lifestyle-related diseases like obesity, Type II

diabetes and hypertension. Active transportation, defined as people completing trips

without the use of a personal vehicle, can provide ways for people to increase their

physical activity levels through walking and cycling.

Traffic calming measures reduce vehicle speed and are recommended by public

health, transportation and policy stakeholders for communities enacting active

transportation policies. Road diets, a form of traffic calming, reduces the number of

travel lanes and are considered a cost-effective way for cities to reduce traffic speed, add

cycling infrastructure and incorporate active transportation.

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Purpose. This study examined the effect of road diets on adult pedestrians and

cyclists by comparing the number of injuries before and after installation of 44 road diets

on Los Angeles city streets from 2004 to 2014.

Methods. Data from the California Statewide Integrated Traffic Records System

(SWITRS) were used to obtain pedestrian and cyclist injuries occurring on the 44 road

diet-improved Los Angeles city streets. A staggered entry design was applied with

injuries averaged for two years prior to improvement and compared to the number of

injuries one year after installation of each road diet for the study period. Paired groups

were pedestrians, cyclists and pedestrians and cyclists combined.

Analysis. A paired t-test was used to calculate the difference between the mean

injuries for each of the three groups. The level of significance was set at 0.05 and square

root transformation was applied revealing a better fit of the count data. In addition,

informal interviews of transportation officials within California were conducted to

understand transportation policy funding and implementation.

Results. The number of injuries to cyclists and total injuries to pedestrians and

cyclists appeared to be higher after the installation of road diets but was not statistically

significant. Injuries to pedestrians appeared to be lower after the installation of road diets

but the difference was not statistically significant.

Conclusions. The association between road diets and pedestrian and cyclist

injuries was inconclusive due to inconsistencies in injuries across groups and streets.

Obtaining valid, reliable data such as traffic, pedestrian and cyclist volumes may help to

clarify the inconsistencies in injuries to these groups. Information gathered from

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transportation officials led to recommendations to improve active transportation policy,

funding, collaboration between sectors and data collection and evaluation standards to

better understand the implications of road diets for active transportation participants such

as pedestrians and cyclists.

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TABLE OF CONTENTS

Glossary of Terms …………………………………………………………………………

List of Tables ………………………………………………………………………………….

List of Figures ………………………………………………………………………………….

Acknowledgements …………………………………………………………………………

CHAPTER 1 - INTRODUCTION

A. Overview …………………………………………………………………………..

B. Background …………………………………………………………………

1. Community Design …………………………………………………

2. Community Design and Public Health …………………………………….

3. Transportation and Health Policy …………………………………………

C. Statement of the Problem

D. Purpose of the Study ………………………………………………………….

E. Research Questions …………………………………………………………

F. Rationale ……………………………………………………………………………

G. Research Gap & Importance to Health Policy ………………………………..

H. Scope of Study …………………………………………………………………..

I. Summary ………………………………………………………………………….

CHAPTER 2 - LITERATURE REVIEW

A. Overview ……………………………………………………………………………

B. Active Transportation in the United States ………………………………………….

C. Active Transportation and the U.S. Built Environment ……………………….

1. Pedestrian and Cyclist Injuries ………………………………………….

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D. Transportation and Health Policy …………………………………………………..

E. Traffic Calming Policies …………………………………………………………...

F. Summary …………………………………………………………………………….

CHAPTER 3 – METHODS

A. Study Design ……………………………………………………………………

1. Setting ……………………………………………………………………

2. Participants ……………………………………………………………………

3. Data Collection …………………………………………………………

4. Data Management …………………………………………………………...

5. Data Analysis …………………………………………………………...

B. Strengths and Limitation …………………………………………………………

1. Strengths …………………………………………………………………..

2. Limitations ………………………………………………………….

C. Research Ethics …………………………………………………………………..

REFERENCES ……………………………………………………………………………

APPENDICES –

APPENDIX A -

APPENDIX B -

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GLOSSARY OF TERMS

Active Living: Integrating physical activity as part of everyday life.

Active Transportation: A form of human-powered transportation, such as walking and cycling. Also known as Utilitarian Transport.

Bike Lane: “A portion of a roadway which has been designated by striping, signing, and pavement markings for the preferential or exclusive use of bicyclists.” American Association of State and Highway Transportation Officials (2012).

Bike Path: An off-street path that is designed for cyclists and/or pedestrians. Some bike paths dedicate space for cyclists, separate from pedestrians; most are multi-use for both cyclists and pedestrians.

Bikeway: Undifferentiated between a bike lane or bike path.

Built Environment: The constructed physical environment that includes transportation systems, land use patterns, and urban design characteristics, which make up a community.

Class II Bicycle Lanes: A dedicated space for cyclists that is separated from vehicular traffic by differentiation, such as striping and color-coded pavement.

Community Active Transportation Policy: A local transportation policy or ordinance developed and implemented at the city or county level to facilitate active transportation within that jurisdiction.

Complete Streets: An example of a community transportation policy and design approach that requires streets to be planned, designed, operated, and maintained to enable safe, convenient and comfortable travel and access for users of all ages and abilities, regardless of the mode of transportation.

Cyclist: An adult 18 years of age or older traveling on a two-wheeled bicycle, in reference to vehicles and roadways.

Infrastructure: Physical items installed at the community level, such as streets, sidewalks, bicycle lanes, lighting, and signage.

Injury: A physical insult to a pedestrian or cyclist as a result of colliding with a vehicle. Injury includes minor to fatal.

Pedestrian: A term that describes an adult 18 years of age or older walking, in reference to vehicles and roadways.

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Road Diets: A type of traffic calming measure that involves reducing the number of travel lanes on a street. Also known as Lane Reductions. Traffic Calming: The combination of mainly physical measures that reduce the negative effects of motor vehicle use, alter driver behavior and improve conditions for non-motorized street users. Urban City: A city with a minimum of 50,000 residents, as defined by the 2010 Census.

Urban Form: The spatial structure and character of a metropolitan area or city, including the physical structures, infrastructure, patterns of movement and land use, and process for its development.

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LIST OF TABLES

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LIST OF FIGURES

CHAPTER 1 – INTRODUCTION

Figure 1.1 Evolution of U.S. street design throughout the 20th century ……………

Figure 1.2 Percent of all transportation trips made by walking or cycling …….

Figure 1.3 Rate of injuries in pedestrian and cyclists per 100 million kilometers

traveled ……………………………………………………………

Figure 1.4 Rate of fatalities in pedestrians and cyclists per 100 million kilometers

traveled …………………………………………………………….

Figure 1.5 Street design before and after road diet …………………………….

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ACKNOWLEDGEMENTS

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CHAPTER 1

INTRODUCTION

A. Overview

Studies show that the way our communities are designed and built influence how

much physical activity residents acquire each day. This built environment includes the

constructed physical environment which contains transportation systems, land use

patterns, and urban design characteristics. Pre-World War II U.S. cities were originally

designed to accommodate what is known as “active transportation,” defined as

transportation that incorporates walking, cycling and public transit from the user’s place

of origin to final destination. Current U.S. transportation policies are auto-centric,

focusing on vehicle speed, auto travel patterns, convenience to drivers and cost. These

policies have contributed to communities designed around the automobile rather than

people, which, in turn, have significantly contributed to a sedentary lifestyle, a lack of

physical activity and an increased incidence of lifestyle-related diseases, such as obesity,

heart disease and diabetes.

A paradigm shift in transportation policies is recommended by a variety of

stakeholders, including public health professionals, transportation planners and policy

makers which focuses on multi-modal transportation, accessibility, cost and health

outcomes. Researchers are now investigating the roles active transportation, urban design

and transportation planning play in making communities accessible by foot, bicycle and

other modes of transportation, beyond the use of a personal motor vehicle. The goal of

this study was to identify if an association existed between community transportation

policy and pedestrian and cyclist injuries resulting from collisions with vehicles.

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B. Background

"If you want to learn about the health of a population, look at the air they breathe,

the water they drink and the places where they live." Hippocrates' words from the 5th

century B.C. still ring true in today's society where the environment in which people live

has a direct, significant impact on how long they live and their quality of life (Kosak,

2000; Gracia & Koh, 2011). Today, a person’s longevity can be predicted based on his

or her residential zip code (Black & Macinko, 2008; Jackson et al., 1992; Williams,

1999).

Throughout the course of modern history, communities have contributed to the

health or infirmities of its residents through their design. In the mid-19th century, Edwin

Chadwick, Britain’s first sanitation commissioner, linked deplorable living conditions to

incidence of communicable disease among its working class. Hence, Britain’s health

reform consisted of designing and building community infrastructure (e.g., sanitary

sewers, water systems, street cleaning, and trash removal) and creating boards of health

to implement, oversee and monitor new community health standards. These changes

dramatically improved the health of residents (Hamlin, 1998). Similar environmental

community policies and infrastructure were implemented in the United States during the

early 20th century. Almost 30 years of increased life expectancy for Americans has been

attributed, in part, to the positive change in community policy (Bunker et al., 1994;

McKeown, 1979).

1. Community Design

Originally, American cities were designed and built on a grid pattern

modeled after British and other European cities (Stanislawski, 1946; Reps, 1965). This

design allowed people and goods to move efficiently through a network of connected

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streets and was followed until the mid-20th century when a change started to evolve in

transportation. During the second half of the 20th century, the population started moving

away from cities and towards newly designed suburban communities (Schuyler, 1988;

Southworth, 1997). Figure 1.1 illustrates the evolution of community street design

through the 20th century from connected to disconnected streets, designed around

vehicles.

Figure 1.1 Evolution of U.S. Street Designs Throughout the 20th Century

Source: M. Southworth (1997)

This movement away from cities into suburbs commenced in the mid-1940s when

U.S. soldiers started returning from World War II. The GI Bill was established for war

veterans to purchase homes being built outside of U.S. cities, incentivizing people to

move away from their hometowns to newly built suburban communities (Checkoway,

1980). Because of this shift in policy from urban to suburban development, the boon of

the automobile commenced and the use of trolleys, the cities’ public transit system,

dissolved due to lack of funding and ridership (Frumkin et al., 2004). Automobiles were

marketed as part of the American Dream: a house in the suburbs and a car to take you

places (Yago, 1984; Kay, 1997).

Also during this post-WWII time, laws were enacted which separated people from

sources of environmental pollutants, such as smoke from factory chimneys, and the

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negative health consequences as a result of living too close to these hazards. Thus, the

environmental planning field began. While these new laws intended to isolate

environmental polluters (factories) from their receptors (housing and residents), the

environmental planning policies did not stop there. Increased segregation between types

of land uses and categories of residents (e.g., wealthy, middle class, and poor) was

thought to be even more beneficial to the community and zoning laws were developed to

compartmentalize American living by land use (Jackson, 1985).

With the separation of people from environmental hazards and the exodus out of

cities into suburbs, the lack of infrastructure to support efficient movement within the

suburbs soon became apparent and the national highway system was established in the

1950s. No one could have guessed that the suburban country-like environment, with

clean air and space between neighbors, would contribute to major public health problems

decades later. Jane Jacobs, an activist in the early 1960s, warned against the then-new

form of municipal planning. In her classic book, The Death and Life of Great American

Cities, Jacobs lobbied against these current practices, less than 20 years after they were

implemented, arguing that urban planning rejects people because it destroys the

‘complexity’ of mixed uses by creating isolated, unnatural spaces (Jacobs, 2011). She

was most famously known for her outspoken criticism of Robert Moses, New York

City’s first planner, who favored highways over public transit. Fifty years later, America

is now reaping the planning seeds sown by environmental and transportation policies

with communities designed around vehicles. The outcomes are sedentary lifestyles and

rising rates of chronic, preventable diseases, such as obesity, diabetes, and heart disease

(Perdue et al., 2003; Frank & Engelke, 2001).

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The design of a community’s built environment contributes to opportunities for

and the amount of physical activity obtained in a particular day by its residents

(Dannenberg et al., 2011). In order to understand the role of the built environment in

transportation, municipal planning and public health, it needs to be defined. The built

environment is referred to as the constructed physical environment which includes

transportation systems, land use patterns, and urban design characteristics (Frank et al.,

2003; Handy et al., 2002). Transportation systems include the physical infrastructure that

support movement, such as roads, sidewalks, bike paths, bridges, and railroad tracks,

along with the frequency of use. Land use patterns include categorization and geographic

distribution of activities. These are commonly grouped into themes, such as agricultural,

industrial, commercial, and residential. Urban design refers to how a city is planned

along with the function, appearance and human appeal of the physical elements.

Therefore, the built environment includes how the physical environment is designed and

constructed to incorporate human activity patterns executed within a geographical

location.

2. Community Design and Public Health

In the late 1990s and early 2000s, researchers began studying the relationship

between the built environment and public health. Some approached this from an

environmental perspective, such as impacts on air quality, land use, and transportation

(Frank, 2000; Handy et al., 2005). Others approached the issue from a health

perspective, such as disease, social equity and capital, mental health and injuries (Ewing,

2003; Frumkin, 2002; Sallis et al., 2006). Transportation and urban planners started

conducting research on how to design communities to increase walking and cycling to

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ease traffic congestion which had exploded with the emphasis on vehicles and highways

(Frank et al., 2003).

Around the same time that research began to identify urban design characteristics

which supported physical activity, the U.S. Surgeon General released a report, entitled

Physical Activity and Health (U.S. Department of Health & Human Services, 1996). In

this landmark report, the increase in the occurrence of certain diseases, including heart

disease, diabetes, obesity, and high blood pressure was linked to a decrease in physical

activity for the first time. Compared to previous studies that identified health benefits of

strenuous physical activity sustained for longer periods of time, this report recognized

that even small amounts of physical activity provided health benefits. The report did not

cover the role the built environment played in obtaining moderate physical activity.

Instead, it paved the way for more research into the field of physical activity and the role

the built environment plays in supporting it. This field of study is better known as active

living, defined as the incorporation of moderate physical activity into everyday life

(Frank, 2000).

Active living incorporates active transportation, defined as walking and cycling

for utilitarian purposes. Active transportation refers to the ability of a person to go to and

from a destination without using a personal motor vehicle (Sallis et al., 2004). It does not

include recreational walking or cycling, but rather travel to a destination by walking,

cycling and using public transportation. Physical environmental attributes which

contribute to active transport at the community level include street connectivity, mixed

land use, and proximity to non-residential destinations (Berrigan and Troiano 2002;

Carlson et al., 2012; Durand et al., 2011; Frank et al., 2005; Litman, 2014; Salens &

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Handy, 2008). Research shows that improvements to walking and cycling infrastructure

have an inverse relationship to vehicle travel: the more people walk and cycle, the less

they drive (Litman, 2014). And the amount of time spent driving has a linear relationship

with the incidence of obesity (Frank et al., 2007; Pucher et al., 2010).

Today, more than two-thirds of Americans are overweight and one-third of this

group is classified as obese (Center for Disease Control and Prevention, 2012). Obesity

has been linked to an increased risk of certain diseases such as cardiovascular disease,

stroke, Type II diabetes, and certain types of cancer (Ogden et al., 2012; CDC, 2012;

Kuczmarski et al., 1994; Mokdad et al., 2001). Obesity is caused by a variety of

lifestyle, environmental, and genetic factors (Martinez, 2000). However, the main cause

of obesity in Americans is the combination of decreased energy expenditure (output) and

increased caloric intake (input) (Bray, 1987; Hall et al., 2011). Compared to other

developed countries, the U.S. has higher rates of obesity, Type II diabetes and

hypertension (Mathers, 2001; WHO, 2002), lower rates of active (non-motorized)

transportation (Pucher & Dijkstra, 2003), and a shorter life expectancy by up to 4.4 years

(Mathers, 2001). According to the Centers for Disease Control and Prevention, only one

in five Americans gets the recommended amount of 30 minutes of daily physical activity

(Center for Disease Control and Prevention, 2012) due in part, because U.S. communities

are designed to facilitate the movement of vehicles rather than people.

Studies show that the way communities are designed and built influences how

much physical activity people get each day (Leyden, 2003; Jackson, 2003; Perdue et al.,

2003; Booth et al., 2005). Creating walkable environments could lead to people walking

more, driving less and weighing less. A study by Frank, et al. (2007) of more than 2,000

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people in the Atlanta, Georgia area, linked neighborhood preference to walkability and

obesity. Those who chose to live in a walkable neighborhood, defined as having mixed

land use, increased residential density and connected streets, walked twice as much as

those who lived in non-walkable neighborhoods, drove half as much and were less likely

to be obese.

As people participate in active transportation, the risk of colliding with vehicles

and sustaining injuries exists because pedestrians and cyclists share the same streets with

vehicles. Roadway injuries are the ninth leading cause of death worldwide and are

predicted to become the third leading cause of death by 2020 (WHO, 2002a; Murray &

Lopez, 1996). Worldwide, more than a million people lose their lives each year as a

result of injuries sustained from vehicles (WHO, 2002b).

According to the U.S. Department of Transportation’s (U.S. DOT, 2013) strategic

plan, “Transportation for a New Generation,” 32,367 people died as a result of motor

vehicle crashes in 2011. Of this number, 4,432 or 14% were pedestrians and 682 or 2.1%

were cyclists. The DOT indicated that this is the lowest fatality rate per 100 million

vehicle miles traveled ever recorded in the U.S. since it started tracking fatalities in 1965

(Litman, 2013). However, the incidence of pedestrian-vehicle and cyclist-vehicle

fatalities and injuries are still considered a public health issue primarily because they are

preventable. As communities embrace active transportation to acquire more physical

activity and reduce traffic congestion, the need becomes critical to enhance the safety of

pedestrians and cyclists while traveling on streets designed for motor vehicles.

3. Transportation and Health Policy

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Since the 1960’s, transportation planning has been evaluated based on

performance, such as mobility (automobile speed, travel convenience) and cost. These

outcomes favor expanding roadways, creating a further dependence on automotive travel,

reducing transportation options such as walking and cycling, and producing a monopoly

on funding for road expansion. These policies have led to increases in vehicular travel,

collisions resulting in injuries and fatalities, and air emissions from vehicle exhaust (e.g.,

particulate matter, carbon monoxide, carbon dioxide and volatile organic compounds)

which degrade the environment (Frumkin, 2002; Woodcock et al., 2009). Proposed

transportation planning criteria include accessibility for all users, integration of multiple

modes and health impact analyses. Transportation demand management (TDM) strategies

with the largest public health impact include traffic calming and speed control measures,

improvements to active transport and public transit, transport pricing reforms, mobility

management marketing, complete streets and smart growth development policies

(Litman, 2013).

Understanding the political climate is important in understanding the recent

proposed shift in transportation policy. The combustion of fossil fuels has been shown to

impact climate change (Davis, et al., 2010; Quadrelli & Peterson, 2007; Ramanathan &

Carmichael, 2008) and motor vehicle fuel consumption is a significant contributor. In

2008, the California legislature passed SB 375, The Sustainable Communities and

Climate Protection Act, which required the California Air Resources Board (CARB) to

reduce the amount of greenhouse gas (GHG) emissions from passenger vehicle use

through the implementation of sustainable communities’ strategies and coordinated

regional transportation plans (California Air Resources Board). Motor vehicles account

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for up to 75% of the GHG emissions within the state (Institute for Local Government).

Therefore, the new driver for transportation policy is an environmental one. Reducing

the number of vehicles is key to reducing GHG emissions and climate change.

Research supports changing transportation policy by demonstrating that a

reduction in vehicle miles traveled can have public health benefits, beyond GHG

reductions and improved air quality. Litman (2013) demonstrated that motor vehicle

travel per capita and crash rates (including injuries and fatalities) have a positive linear

relationship: as one increases, so does the other. Studies show that a 1% decline in

vehicle miles traveled corresponds to a 1.4 to 1.8% reduction in vehicle crashes (Litman,

2004; Edlin, 2002). This data contradict previous transportation data which show that

crash rates, including injury and fatality rates, have decreased per 100 million vehicle

miles traveled, from 1965 to 2010, primarily due to enhanced vehicle safety features

which have improved occupants’ crash survivability. The reality is that among peer

countries (those with similar economies and rates of vehicle use), the U.S. has the highest

per capita crash rates for cyclists (3 to 5 times higher) and pedestrians (5 to 6 times

higher), even with significant advances made in vehicle safety (Buehler & Pucher, 2012).

When compared to the U.S., Germany and The Netherlands had higher rates of trips

made by walking or cycling (see Figure 1.2) but lower rates of injuries. Figure 1.3

illustrates that American pedestrians and cyclists are more likely to be injured than their

counterparts in Germany and The Netherlands. Figure 1.4 illustrates this relationship of

transportation type (walking, cycling) to fatalities. Pucher and Dijkstra (2003) suggest

that U.S. pedestrian and cyclist injuries are higher due to a lack of policy and

infrastructure that supports active transportation. Improvements such as walking and

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cycling facilities, residential design, traffic calming, education, enforcement and

restricting vehicle use have been demonstrated as effective in Germany and The

Netherlands in reducing pedestrian and cyclist collisions with vehicles and the resulting

injuries sustained from these accidents.

Figure 1.2 Percent of all Transportation Trips Made by Walking or Cycling

Source: Pucher and Dijkstra, 2003.

6

22

18

1

12

28

0

5

10

15

20

25

30

USA GER NDL

Percent of All Trips

Walking Cycling

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Figure 1.3 Rate of Injuries in Pedestrians and Cyclists per 100 million Kilometers Traveled

Source: Pucher and Dijkstra, 2003.

0

5

10

15

20

25

30

USA GER NDL

Injuries per 100 Million km Traveled

Pedestrain Cyclist

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Figure 1.4 Rate of Fatalities in Pedestrians and Cyclists per 100 million Kilometers

Traveled

Source: Pucher and Dijkstra, 2003.

Researchers have made specific policy recommendations for communities to

implement, which include high residential density (Frank, 2000; Frank et al., 2005;

Durand et al., 2011); street connectivity (Frank, 2000; Frank et al., 2005; Carlson et al.,

2012); pedestrian and bicycle infrastructure (Bassett et al., 2008; Pucher & Buehler,

2008; Pucher et al., 2010); mixed-use zoning (Frank, 2000; Frank et al., 2005; Pucher &

Buehler, 2008; Pucher et al., 2010); traffic calming measures to reduce vehicle speeds

(Pucher et al., 2010); and comprehensive education for everyone on rights-of-way for

cyclists and pedestrians (Pucher et al., 2010). Studies also show that reconnecting land

use and transportation decisions not only decreases costs for implementation and

maintenance, but also increases community and economic development (Smart Growth

America, 2012).

0

2

4

6

8

10

12

14

16

USA GER NDL

Deaths per 100 Million km Traveled

Pedestrian Cyclist

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Although policy recommendations have been studied, active transportation has

taken many years to implement, particularly with the focus on vehicles. Oregon was the

first state in the U.S. to enact active transportation legislation in 1971. ORS 366.514,

better known as the Bike Bill, stated that footpaths and bicycle trails would be provided

whenever a highway, road or street was being constructed, reconstructed or relocated

(The Bike Bill). However, it wasn’t until 30 years later that a corresponding federal

policy was adopted to incorporate bicycling and walking facilities into all transportation

projects (Shinkle, 2007). The roadblock to implementing this federal policy was the lack

of allocated funds for projects that incorporated cycling and pedestrian infrastructure,

thereby limiting the effectiveness of the federal legislation on a wider scale, particularly

at the state and community levels.

Thirty-five years after Oregon enacted active transportation policy, a national

movement started to make active transportation policy commonplace in communities

across the U.S., called Complete Streets. This strategy started in 2005 and included

policy advocates such as the American Public Transportation Association, the American

Planning Association and the American Public Health Association. These organizations

formed the National Complete Streets Coalition, an advocate for Complete Streets

policies adopted by states and municipalities based on the context of the environment,

rather than prescriptive standards (National Complete Streets Coalition).

One of the coalition’s recommendations is called ‘traffic calming’ which

implements a variety of physical changes in roadways to reduce speed behavior in

motorists and potentially reduce collisions with other vehicles, pedestrians and cyclists.

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These include narrowing travel lanes from the recommended 12 feet in width to 10-11

feet, based on research from the National Cooperative Highway Research Program

(2007); road ‘diets’ which reduces a four-lane road down to three lanes, based on average

daily traffic volumes up to 20,000; raised medians, which visually narrows the roadway

and provides a place of refuge for mid-block crossings; median and parkway landscaping,

which further visually narrows the roadway; curb parking, which provides access while

creating a significant calming effect due to the presence of pedestrians; and curb ‘bulb-

outs,’ which controls parking, pedestrian crossing distances and improves lines of sight

(LaPlante & McCann, 2008). While these are considered best practice for transportation

planning, no evaluation has been identified in the literature to determine if these policies

improve the safety of pedestrians and cyclists by reducing their rate of collisions with

vehicles and the corresponding injuries they suffer as a result.

C. Statement of the Problem

As more communities enact active transportation policy and install supportive

infrastructure, more pedestrians and cyclists are “hitting the pavement.” This creates an

exposure to vehicle traffic and a risk of injury from colliding with a vehicle.

D. Purpose of the Study

The purpose of this study was to identify a relationship between a reduction in

vehicle travel lanes, or road diets, a form of traffic calming, and pedestrian and cyclist

injuries.

E. Research Questions

One type of traffic calming measure was examined, road diets, to determine the

effect of reducing vehicle travel lanes on the incidence of pedestrian and cyclist injuries.

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1. What association does a road diet have between pedestrian and cyclist

injuries?

The null hypothesis (Ho) stated that no statistical difference existed between pedestrian

and cyclist injuries before and after the implementation of road diets.

F. Rationale

Reducing vehicle speed correlates to a significant reduction of risk of injury and

fatality to pedestrians (Richter et al., 2006; Rumar, 1999). A study by the British

Department of Transport found that the risk of pedestrian fatalities rose from 5% at

impact of 20 miles per hour (mph) to 45% at impact of 30 mph to 85% at impact of 40

mph (Surface Transportation Policy Project, 1997). This means that the faster the vehicle

is traveling at the moment of impact for a pedestrian, the more likely the collision is to be

fatal for the victim. The same holds true for cyclists because neither of these groups have

safety mechanisms to reduce the impact from a vehicle, such as a restraint or air bag.

One way of reducing vehicle speed is installing traffic calming measures (Richter

et al., 2006; Leaf & Preusser, 1999). These measures are physical elements installed on

streets and roads to reduce traffic speeds, volume, traffic collisions, traffic-generated

noise, and enhance pedestrian street crossing safety. They can be applied to streets

located in both residential and commercial land uses (Mead et al., 2013). Examples of

traffic calming measures include narrowing traffic lanes, reducing the number of traffic

lanes, widening sidewalks, installing chokers or curb bulb-outs, installing raised cross

walks or speed humps, and installing a treated segment of the roadway to change the

sound of the road to the driver (LaPlante & McCann, 2008). Elvik (2001) estimated that

traffic calming measures had an effect by reducing vehicle collisions by an average of

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15%. However, only vehicle-to-vehicle accidents were studied and did not include

pedestrians or cyclists.

Selecting the most appropriate traffic calming measure requires an understanding

of transportation funding. According to the Institute on Taxation and Economic Policy

(2013) cities across the U.S. are dealing with shrinking transportation budgets, due to

decreased federal funding from a reduction in gasoline sales and corresponding taxes.

This loss comes from two sources: 1) a reduction in actual fuel purchasing due to

increased fuel efficiency of vehicles, and 2) no increase in the federal excise tax on

vehicle fuels sold since 1993. These combined factors equate to tax dollars collected

having only two-thirds of the buying power, compared to 20 years ago. In turn, this

means that local jurisdictions, such as cities and counties, have to prioritize the

expenditure of their reduced transportation budgets to maximize the benefit.

The cost to implement traffic calming measures varies depending on the type. For

example, extending sidewalks or building a raised median costs an average of $100,000

per mile, an expensive investment. Costs for restriping a street from four lanes down to

three (two travel lanes and one two-way median left turn lane) and adding a bike lane

each way range from $5,000 to $20,000 per mile, depending on the number of lanes to be

painted (Zegeer et al., 2002). Figure 1.5 illustrates the concept of implementing a road

diet, before and after restriping. Because of this lower cost of implementing street lane

reductions, more cities are presumed to employ this traffic calming measure. Thus, the

method of lane reductions is selected for this study to determine the effect of traffic

calming on vehicle collisions with pedestrians and cyclists.

18

Figure 1.5 Street Design before and after Road Diet

Source: McCormick, 2012.

19

G. Research Gap and Importance to Health Policy

Active transportation policy is relatively new for communities. While limited

studies in the U.S., Europe, Canada and Australia have focused on traffic calming

measures (Mead et al., 2013) the impact of implementing traffic calming measures by

reducing vehicle travel lanes on pedestrian-to-vehicle and cyclist-to-vehicle collisions

was not found in the literature (Brownson et al., 2006; Chen et al., 2012; Mead et al.,

2013).

In addition, a conflict existed in the literature. Does an increase in pedestrians

and cyclists equate to an increased risk of vehicle collisions? Pucher et al (2010) noted

an increase of 247% in bike lanes and paths in Portland, Oregon from the period of 1991-

2008. During this time, the share of workers commuting by bike increased from 1.1% to

6%. Simultaneously, the rate of cyclist-to-vehicle collisions increased by 14% (City of

Portland, 2008a and 2008b). However, Pucher et al (2010b), Elvik (2001), Jacobsen

(2003) and Robinson (2005) found that injury rates fell with increased rates of cycling in

other U.S. cities. Therefore, it was unclear whether the presence of cyclists and

pedestrians traveling on streets improved by road diets increased the incidence of

collisions with vehicles.

Understanding the significance of traffic calming measures on pedestrian and

cyclist injuries can help local decision makers to implement better transportation policies,

reduce the risk of injury to the community and increase rates of active transportation.

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H. Scope of Study

A staggered pre/post entry design identified and mapped streets within the city of

Los Angeles, California that were improved using road diets. Pedestrian and cyclist

injuries were geo-coded and mapped using GIS to determine the impact before and after

street improvements. An urban environment was selected because most injuries to

pedestrians and cyclists occur in urban and suburban areas rather than rural primarily due

to higher numbers of vehicles, pedestrians and cyclists (Ewing et al., 2003; Morency et

al., 2012). This study did not include highways or freeways for the following reasons: 1)

they lack infrastructure, such as sidewalks to support pedestrians, or bike lanes to support

cyclists; 2) pedestrians and cyclists cannot use these major roads for active transportation

due to state and federal policy restrictions; and 3) major roads are financed by state and

federal funding and controlled by corresponding policy, rather than community-level

funding and policy. In addition, this study focused on adults because active transportation

is defined as people completing trips without the use of a personal vehicle. Active

transportation does not include cycling or walking for exercise or recreation.

I. Summary

A shift in community-level policy has started to incorporate modes of active

transportation through infrastructure improvements. However, with limited resources,

cities are forced to prioritize which improvements to make. Reducing traffic lanes

through road diets are a relatively inexpensive infrastructure improvement to reduce

traffic speed and enhance active transportation opportunities. It was unknown whether

such transportation infrastructure changes resulted in fewer pedestrian and cyclist

21

injuries. The intent of this study was to determine what impact road diets have on

pedestrian and cyclist injuries resulting from collisions with vehicles.

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CHAPTER 2

LITERATURE REVIEW

A. Overview

Active transportation and the community built environment characteristics play a

role in vehicle accidents involving pedestrians and cyclists. The United States is

significantly behind other first-world nations in rates of active transportation. In addition,

it has one of the highest rates of injuries and fatalities for pedestrians and cyclists (Pucher

& Dijkstra, 2003). This is in great part due to a lack of policy that provides adequate

road space to carry out active transport and programs to enhance the safety of all roadway

users, particularly those outside of a vehicle.

In this literature review, peer-reviewed journal articles, white papers, monographs

and other supporting documents were included if they covered active transportation, the

built environment, adult pedestrian and cyclist injuries related to vehicle collisions, traffic

calming measures, and policy recommendations supporting these topics. Search engines

used included PubMed, EBSCO, and Google Scholar. Search terms included “active

transportation”, built environment”, “pedestrian injuries”, “cyclist injuries”, “traffic

calming measures”, “road diets”, and a combination of these terms. In addition,

bibliographies were examined for additional supporting references. Literature on

walking or cycling injuries related to children, walking or cycling related to leisure

activities, behavior modifications and social determinants related to injuries and vehicle

collisions were not included in this review because they were not part of the scope of this

research.

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B. Active Transportation in the United States

The United States has the lowest rate of active transportation, compared to

European countries and Canada, with approximately 6% of trips made by walking and

1% made by cycling (Pucher & Dijkstra, 2003). Canada has somewhat higher rates of

10% and 2%, respectively, and The Netherlands boasts active transportation rates of 18%

and 28%, respectively. In the U.S., rates of active transportation decrease with age.

However, these rates increase with age in both The Netherlands and Germany where

about half of all trips by people age 65 years and older are made by walking or cycling

(Pucher & Dijkstra, 2003). These variations are attributed to distinct differences in

infrastructure and policy. For example, the Netherlands has extensive cycling and

walking infrastructure which support active transport, such as a network of dedicated

bicycle paths, connected streets with sidewalks, traffic calming in residential

neighborhoods, and car-free zones. In addition, the Dutch government has enacted

policies over time that restricts automotive travel through disincentives, such as levying

increased taxes and implementing parking restrictions, making vehicle ownership

expensive and inconvenient (Buehler, 2010; Pucher et al., 2010). On the other hand, U.S.

transportation policy makes automotive travel easy and inexpensive for the majority of

Americans through lower taxes, lower gasoline prices, plentiful parking and

infrastructure that supports vehicle travel.

Buehler et al (2011) compared active travel, or non-motorized transport, in the

U.S. and Germany and found that German residents had a higher number of hours spent

in active transportation than their American counterparts. National travel survey data

were used from each country for comparison. These two countries are similar in many

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respects: affluence, market-based economy, democratic government, large roadway

systems, high rate of vehicle ownership, significant contribution of the automotive

industry to the national economy (although Germany has a two-fold increase in the

automotive industry contribution to its economy over the U.S.), and similar proportion of

licensed drivers. The number, duration and distance of walk or cycle trips was twice as

high in Germany as in the U.S. Among all age groups, Germans had higher rates of active

travel than those in the U.S. Germans walked an average of 112.5 hours annually whereas

Americans walked an average of 39.1 hours. Germans also cycled more than their

American counterparts (39.1 versus 4.7 hours per year). The difference in rates is

attributed to the number of people participating in active travel: 21.2% of Germans

walked 30 minutes or more per day versus 7.7% of Americans while 7.8% of Germans

cycled 30 minutes or more per day versus 1.0% of Americans. Increasing active transport

in the U.S. will likely require multiple efforts, such as changing policy to favor active

travel over vehicles, land use planning and zoning for increased density and mixed-use,

and programs to promote these alternative forms of transportation, particularly for the

elderly, children and women who view walking and cycling as more dangerous than men.

Increasing physical activity through active transportation can have potential

health and economic benefits. A study performed by the New Zealand Transport Agency

(2010) estimates the net health benefits of increased physical activity to be US$3.70 per

additional mile walked and US$1.92 per additional mile cycled. A cost-benefit analysis

of using bike/pedestrian trails in Lincoln, Nebraska revealed a health benefit ratio of 2.94

compared to the per capita cost of building the trails (Wang et al., 2005). Research by

Cavill et al (2008) and Saelensminde (2004) concluded that the environmental and health

25

benefits of cycling in a community are four to five times the cost of cycling infrastructure

investment. Gotschi (2011) used costs of past and planned bicycle investments and

compared them to healthcare cost savings and mortality reduction to calculate an

estimated $7.5 to $12.8 trillion benefit in healthcare savings, fuel savings and longevity

benefits for Portland’s 40-year, $600 million bicycle facilities investment. This

information is important for policy makers because it demonstrates that increased funding

of active transportation infrastructure supports health benefits to the residents of their

communities. This, in turn, could reduce healthcare expenditures at the local, state and

national levels through residents acquiring the recommended 30 minutes of daily physical

activity and developing more active lifestyles.

Quantifying the rate of active transportation is crucial in order to determine the

risk to those participating in this form of physical activity. In the U.S., active

transportation is tracked by the National Household Travel Survey (NHTS), a U.S.

Department of Transportation (DOT) program sponsored by the Bureau of Transportation

Statistics (BTS) and the Federal Highway Administration (FHWA). This survey collects

data on both long-distance and local travel by the American public and gathers trip-

related data such as mode of transportation, duration, distance and purpose of trip. It also

gathers demographic, geographic, and economic data for analysis purposes. The NHTS

is a telephone-based survey, conducted most recently in 2009, and is used by researchers

to determine amounts of active transportation among Americans.

Using the 2001 NHTS survey data, Besser and Dannenberg (2005) found that of

the 3,321 respondents who reported walking to and from transit (3.1% of the 105,942

total respondents), the mean total walking time was 24.3 minutes with a median walk

26

time of 19.0 minutes. When weighted for age, income, education, ethnicity, gender and

car ownership, those who were in the lowest income bracket (<$15,000/year), living in

the highest density areas (>25,000 people per square mile), who were least educated

(high school diploma or less), belonged to an ethnicity category other than Caucasian,

and lived in a household without a car were found to have significantly higher mean total

walk times. This information is important in that it demonstrates that urban residents can

and do participate in active transportation because their built environment supports it

better than suburban or rural environments. In addition, it demonstrates that urban

residents are able to achieve the recommended 30 minutes a day of moderate physical

activity through active transportation.

Pucher et al (2011) compared the NHTS data from 2001 and 2009 to determine if

there were any increases in active transport (walking and cycling). They found that a

statistically significant, although small increase occurred in walking for active

transportation. On average, more Americans walked - 5 more hours, 9 more miles and

completed 17 more walking trips - in 2009 as compared to 2001. In contrast, the

additional time spent cycling – on average, 5 more miles and two more trips completed

per year - was not a statistically significant change. The suggested reason is that the same

number of people cycled during this time, rather than having an increase in total number

of cyclists. These increases were not evenly distributed among groups. In fact, active

transport rates significantly declined for women, children and those 65 years and older,

but increased among men aged 25-64, those without a car, the employed and those well-

educated.

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Additional studies found Americans spend less time performing active

transportation than Europe and Canada. This difference is attributed to U.S. policies that

support personal vehicle transportation (Buehler, et al., 2011; Buehler, 2010; Pucher et

al., 2010). A suggested reason for these differences is personal safety: women, children

and the elderly do not feel safe on streets designed for cars. However, risk of collision

with a vehicle while cycling, whether real or perceived, is a significant factor why more

people are not participating in active transportation.

C. Active Transportation and the U.S. Built Environment

The way communities are designed influences how much physical activity its

residents achieve. Cervero and Radisch (1996) studied two differently designed

communities in San Francisco. Both neighborhoods had similar income levels and

transportation services. Residents of the Rockridge community, with higher density and

mixed land uses, were five times more likely to walk to a destination than the residents of

the Lafayette community, which had larger housing-tract lots and poorly connected

streets.

Berrigan and Troiano (2002) used the third NHANES data to examine the

association between age of housing and walking behavior. Results revealed that adults

who lived in homes built prior to 1973 were more likely to walk at least one mile 20 or

more times per month. This behavior was found in both urban and suburban counties.

However, in rural counties this association was absent, suggesting that home age is not

associated with environmental walking features in rural areas, supposedly due to longer

distances between origin and destination, compared to urban and suburban counties.

These results concur with the authors’ hypothesis that environmental variables, such as

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age of neighborhood housing, support walking behavior. This is because older

neighborhoods were built according to former land use policies and patterns of street

connectivity and mixed land use supporting active travel, compared to current land use

policies of separation which support automotive travel.

Frank et al (2004) examined the results of a travel survey conducted between

2000 and 2002 of nearly 11,000 participants in the Atlanta, Georgia region. The purpose

of the study was to evaluate participants’ place of residence within the built environment

and its relationship with body mass index (BMI), obesity specific to gender, ethnicity,

and self-reported travel patterns. This cross-sectional study used self-reported data such

as height and weight to determine the relationship of urban form (e.g., land use mix,

residential density, and street connectivity) with BMI, obesity, and activities related to

transportation, while adjusting for socioeconomic and demographic factors. The odds of

obesity occurring were reduced by 12.2% for each quartile increase in land-use mix and

by 4.7% for each kilometer walked per day. Conversely, each additional hour spent

commuting in a car was associated with a 6% increase in the likelihood of obesity. These

relationships were stronger among white than black participants, due to white participants

living in lower density, more homogenous land use neighborhoods and spending more

time traveling in automobiles, which is a sedentary activity. This was one of the first

studies on urban form and its relationship with obesity using empirical data.

In the National Quality of Life Survey (NQLS), Frank et al (2006) studied

residents in King County, Washington for neighborhood walkability, air emissions and

BMI. They found a 5% increase in walkability, which was calculated from residential

density, street connectivity, land use mix and retail floor area ratio. This change was

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associated with a 32.1% increase in time spent in active transportation, a 0.23 point

reduction in BMI, 6.5% fewer vehicles miles traveled, 5.6% fewer grams of nitrogen

oxides (NOx) emissions and 5.5% fewer grams of volatile organic compounds (VOC)

emissions.

Walkability is associated with low income urban areas due to the date of design,

street connectivity, mixed land use and high density. However, residents in these areas

also suffer higher rates of chronic diseases and decreases in personal safety, healthy food

outlets and opportunities for recreation. Neckermann et al (2009) compared low and high

income neighborhoods in New York City. Using GIS and field observations, they

determined that low income neighborhoods had higher rates of crime, fewer trees at the

street level, dirtier streets and higher rates of vehicular crashes. Other studies (Beck et

al., 2007; Buehler et al., 2011) report that specific groups, such as the elderly, children

and women do not perform as much active transportation as men because they do not feel

safe. Improving esthetics and safety for residents may help to reduce health disparities

by providing safer walking conditions to improve active transportation in low-income

urban areas.

Another urban low income area study by Parker (2011) counted observed bicycle

use to determine increased usage and ridership after installation of the first dedicated bike

lane in downtown New Orleans, located along St. Claude Avenue. Results showed an

increase in the mean number of cyclists per day of 142.5 after installation of the bike

lane, compared with pre-installation at 90.0 (p <.001). A significant 133% increase in the

number of women cyclists was also observed (average daily mean pre-installation of

12.6, compared with post-installation of 29.4) compared with a 44% increase among men

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cyclists (77.0 versus 111.2). Improved infrastructure, such as installing bike lanes in

urban areas, can play an important role in increasing physical activity and active

transportation, particularly for low income female residents who do not feel safe cycling

on city streets.

The built environment plays a key role in facilitating active transportation for

urban and even suburban residents through connected streets, mixed land use and higher

density neighborhoods. History is a good lesson for planners: the way communities

were designed facilitated the movement of people with streets that were connected to

destinations, mixed land uses and an increased density of people within cities.

1. Pedestrian and Cyclist Injuries

With an increase in active transportation in the U.S., particularly on streets

designed for vehicles, an increased risk of collision, injury and/or fatality exists for

pedestrians and cyclists. Chidester and Isenberg (1999) collected pedestrian crash data

from six large U.S. cities from July 1994 to December 1998 and analyzed 521 cases

selected for inclusion. While the purpose of their study was to determine the cause of

pedestrian-vehicle injuries based on safety standards of vehicles, the results reveal

important data about the non-occupants, or pedestrians and cyclists, injured by vehicles.

The majority of pedestrian victims (58%) were age 19 to 65, with males (51%) and

females (49%) almost evenly distributed. Additionally, 2% of pedestrian victims were

over age 80 years. However, 64% of these cases died as a result of their injuries. Of the

vehicles involved in the crashes, 68% were passenger vehicles and 65% of the total

injuries sustained were from contact with the passenger vehicle. Prior to the crash, 55%

of the pedestrians were walking and 38% were running or jogging. Eighty-seven percent

31

were attempting to cross a roadway. However, these were evenly divided between

crossing at an intersection and a non-intersection street location. The majority of crashes

occurred during the day (65%) and in good weather (87%). The impact of speed as a

measure of severity of injury was noted in 82% of the cases. While this is not a

representative sample of all pedestrian-vehicle crashes, it does provide some general data

to consider, such as speed of vehicle, age of pedestrian (young adult) and location

(attempting to cross a roadway).

Wedagama et al (2006) studied the relationship between pedestrian and cyclist

injuries in two adjacent analysis zones constructed around Enumeration Districts (which

are similar to U.S. Census tracts) in the United Kingdom (U.K.). Using police accident

report data from 1998 to 2001, land use classification, U.K. census data, and road data,

such as length and number of intersections, injured pedestrians and cyclists were

categorized by accident time of day as during work hours or after work hours. Both

pedestrian and cyclist injuries were associated with an increase in retail and community

land uses during working hours. An increase of 0.10 in the proportion of retail land use

estimated an increase factor of adult pedestrian injuries by 1.67; the same increase of 0.10

in the proportion of community land use estimated an increase injury factor of 1.21. For

adult cyclist injuries, an increase by 0.10 of retail land use increased injuries by a factor

of 2.28. These were all found to be statistically significant (p <0.05). These findings

suggest that retail and commercial land use attract people, yet these land uses conflict

with vehicle use by creating an increased exposure to pedestrians and cyclists. European

countries have lowered their pedestrian and cyclist injuries by enacting policies that

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create car-free zones (Pucher & Dijkstra, 2003; Pucher et al., 2010), especially important

in areas where large amounts of people gather such as downtown urban areas.

Compared to the U.K., the U.S., collects injuries and fatalities involving vehicles,

including pedestrians and cyclists, through the National Highway Traffic Safety

Administration (NHTSA). Data is aggregated and reported annually by state. The

Fatality Analysis Reporting System, or FARS, collects and reports data on all vehicle-

related fatalities. Similarly, NHTSA collects and reports injury data separate from

fatality data, in the General Estimates System, or GES, database. In California, the

Highway Patrol collects injury and fatality data in the Statewide Integrated Traffic

Records System (SWITRS) database. This database is different from NHTSA in that it

collects and reports injury and fatality data by county and city, distinguishing cyclists and

pedestrians from vehicle occupants.

Using data from the Fatality Analysis Reporting System (FARS) for fatal injuries,

the General Estimates System (GES) for non-fatal injuries, and the 2001 NHTS for travel

behaviors, Beck et al (2007) calculated the risk of injury based on gender, age and mode

of travel. The overall annualized fatal injury rate was 10.4 per 100 million person-trips;

bicyclists (21.0) and pedestrians (13.7) had higher rates, while bus riders (0.4) had the

lowest rate. Males had a significantly higher rate of fatal injury (14.6) compared with

females (6.5), due, in part, because more men than women participate in cycling. Age

group 15-24 years had the highest overall fatal injury risk (20.9), followed by age group

65 years and older (16.6). Those age 65 and older had a significantly higher fatal injury

rate for walking (27.1). The overall nonfatal injury rate was 754.6 per 100 million

person-trips. Pedestrians (215.5) had a lower risk; cyclists (1,461.2) had a much higher

33

risk and bus riders (160.8) had the lowest risk. These results demonstrate that pedestrians

and cyclists are more likely to be fatally injured in the U.S. and that bus travel is the

safest mode. Additionally, this data show increased risk to those who are participating in

active transportation (walking, especially cycling). What is noteworthy about this study

is that people 65 years and older rarely participate in cycling due to an unsupportive

physical environment. Appropriate infrastructure such as bicycle lanes, connected

sidewalks and car-free zones, support the concept of “aging in place”, where people can

continue to live and travel in their neighborhoods through active transportation of cycling

and walking, rather than travel in personal vehicles. In addition, cyclists have a higher

rate of injury, presumably due to their different speed of travel from cars and pedestrians,

and that they are sharing the same physical space as vehicles, creating the risk of

collisions and injuries. This is similar to motorcyclists, who had an extreme risk of fatal

injury (536.6), compared to the overall fatal injury risk (10.4).

Wier et al (2009) developed a multivariate, area-level regression tool to quantify

the risk to pedestrians of vehicle collisions and used it to predict changes in injuries,

based on projected traffic volumes for development projects in 176 census tracts in San

Francisco, California. Data from the Statewide Integrated Traffic Records System

(SWITRS) were used to obtain pedestrian-vehicle collisions on public roadways in San

Francisco from 2001-2005. Variables for predicting this change included street data, land

use characterization and commute behavior data. The outcome revealed that 72% of the

variation in census-tract pedestrian-vehicle collisions were explained by the model,

which included traffic volume, arterial streets without public transit, land use, proportion

of land use zoned as commercial or residential, poverty levels and proportions of those

34

age 65 years and older. Traffic volume had the highest adjusted partial correlation (r

=.454) to pedestrian-vehicle collisions. Other adjusted partial variable correlations

included number of employees (r =.358), proportion of land use zoned as commercial (r

= .323), proportion of arterial streets without public transit (r = .314), and resident

population (r = .303). This means that a 15% increase in traffic volume at the census

tract level is associated with an 11% increase in pedestrian-vehicle collisions. Similarly,

a 15% increase in area employees is associated with a 3% increase in collisions between

pedestrian and vehicles.

Morency et al (2012) performed a multi-level observational study in Montreal,

Canada to determine the extent to which road characteristics and traffic volume explain

socioeconomic inequalities in vehicle-related injuries. When compared with higher

income census tracts, the poorest census tracts had statistically significant increases of

injuries for pedestrians (6.3 times greater), cyclists (3.9 times greater) and vehicle

occupants (4.3 times greater). Traffic volume was also significantly higher in high

poverty census tracts: an increase of 1,000 vehicles per day at an intersection was

associated with an increase in pedestrian injuries by 6%, cyclist injuries by 5%, and

vehicle occupant injuries by 7%, due to the increased number of major roads and

intersections in these neighborhoods. In addition, rates of walking, cycling and using

public transit were also significantly higher in poorer census tracts likely because 49% of

the residents did not own a personal vehicle. Population density was shown to be related

to pedestrian injuries at intersections in poorer neighborhoods. These factors account for

an increased risk of injury for all road users.

35

Zegeer et al (2002) conducted a study to determine the types of risks pedestrians

encounter when walking along a roadway. In addition, they quantified the relationship of

these risks to specific neighborhood and roadway factors, such as sidewalks, traffic

volume, vehicle speed, and roadway and shoulder width. For each of the 47 crash sites

identified, two comparison sites were selected – one within a mile of the site and one

further away but within the same county. A lack of walkable space, the absence of a

sidewalk, traffic volume and vehicle speed were associated with an 88.2% higher risk of

a pedestrian/vehicle crash. When controlling for roadway features, socioeconomic factors

associated with a higher pedestrian/vehicle crash risk included single-parent households,

unemployment rate and older housing units.

In summary, pedestrians and cyclists are exposed to an increased risk of injury or

fatality while performing active transportation on roads designed for vehicles. Vehicle

speed is one of the most significant factors in the severity of injury to both pedestrians

and cyclists. Other factors include higher rates of poverty, increased traffic volume,

residential density and lack of designated space, such as sidewalks or bicycle lanes.

These factors should be considered when examining the relationship between various

built environment factors and injuries to pedestrians and cyclists.

D. Transportation and Health Policy

The current focus of federal transportation policy is on highway and road

transportation projects. For example, the Moving Ahead for Progress in the 21st Century

Act, or MAP-21 earmarks only 2% of the $105 billion in total funds to Transportation

Alternatives category, such as recreational trails, Safe Routes to Schools program, and

planning, designing, or constructing roadways within the right-of-way of former

36

Interstate routes or other divided highways (U.S. DOT FHWA, 2015). California’s

Transportation Development Act of 1971 provides two funding sources for public transit

and allocates only 2% of its annual $314 million in funds for pedestrian and bicycle

projects (Elgart, 2013). Currently, U.S. transportation policy remains dedicated to

vehicles as the primary transportation mode. More research is needed to determine how

transportation policy and funding can be used to promote active transportation as a safe

way of moving people without a vehicle.

Librett et al (2003) surveyed the state of Utah’s city ordinances to determine

policies for six domains of physical activity: sidewalks, bike lanes, shared-use paths,

work sites, greenways and recreational facilities. Seventy-four cities were included and

categorized into low, medium and high-growth, based on the governor’s planning and

budget office projections for the next 30 years. High growth cities reported more

ordinances related to physical activity, such as sidewalks, master plans and recreational

activities. A data collection survey tool was developed and implemented to capture this

information, which can be used to provide support for municipalities and public health

agencies as to where to focus their limited resources to improve their residents’ health.

Rietveld and Daniel (2004) analyzed the role that policy played in bicycle use in

The Netherlands, which boasts one of, if not the highest active transportation rates in the

world. Using national data collected by the Dutch Cyclists’ Union, they found a positive

correlation (r=0.33) between local municipal policy implementation and bicycle use.

Control variables in the analyses included population density, age, ethnicity, political

affiliation, presence of a university, and topography. Four significant policy-related

variables that increased bicycle use were greater commute speed (relative to vehicles),

37

fewer hindrances, increased parking costs and enhanced safety for cyclists. Researchers

found that if the trip was perceived as 10% faster by bike than automobile, then bicycle

use increased by 3.4% and if there were less than 0.3 stops per kilometer, bicycle use

increased 4.9%. Likewise, if car parking costs increased by 14 eurocents per hour,

bicycle use increased 5.2%. Over a four year period, if one less victim of a pedestrian-

vehicle collision occurred per one million bicycle kilometers traveled, bicycle use rose

1.1%, showing increased perception of enhanced safety. This research demonstrates that

enhancing the attractiveness of using a bicycle relies in part on effective policies and

implementation that encourage and allow people to walk or cycle by providing safe, easy

and cost-effective alternatives to using a personal motorized vehicle.

Among cities who have invested in active transportation infrastructure, bike lanes

and paths have the most influence on increasing bike travel. Dill and Carr (2003) sampled

42 of the largest U.S. cities and found a 1% increase in cycling rates per each additional

linear mile of bike lanes per city square mile. Buehler and Pucher (2012) analyzed data

from 90 of the top 100 largest U.S. cities with bike lanes and paths to determine the

relationship between bikeways and active transportation cycling levels while controlling

for a range of influencing factors, including safety (number of fatalities), socioeconomic

levels (% of households without a car and share of students), land use (composite sprawl

index including density, mix of land uses and street connectivity), gasoline prices

(averaged per state), supply of transit (measured in vehicle miles per capita) and climate

(precipitation levels and average number of days at extreme temperatures - below 32oF

and above 90oF). Cities were grouped into quartiles based on supply of bike paths and

lanes (bikeways). Results revealed that cities with the highest supply of bikeways (4th

38

quartile) have 3 to 4 times higher rates of Active Transportation cycling (7.8 per 100,000

population) compared to those cities with the lowest supply of bikeways (2.5 per 100,000

population).

Reynolds et al (2009) reviewed 23 studies regarding infrastructure and cyclist

safety that revealed several key principles in conducting research on this topic: defining

infrastructure terms (there are differences across countries); studying specific

infrastructure (e.g., intersection crashes were studied almost exclusively in Europe,

whereas straightaway crashes were studied in North America); including information on

roundabouts (which replace intersections) which are very common in Europe and have

been shown to reduce crash risk for motor vehicles by 30-50% (Elvik, 2003); accounting

for the underreporting of injuries and crashes, particularly, minor injuries, near-misses

and fatalities. Evidence from three studies reviewed by Reynolds et al (2009) suggests

that bicycle-only facilities (e.g., dedicated bike lanes and paths) reduce the risk of crashes

and injuries compared to on-road cycling with traffic or off-road cycling with pedestrians

(Kaplan, 1975; Lott & Lott, 1976; Smith & Walsh, 1988).

Bicyclists are at increased risk of crashes and injuries when riding on streets

designed for vehicles because bicycles offer no protection to the cyclist when faced with

the higher speed and the greater mass of a vehicle. In North America, bicycle helmet use

has been extensively studied (Thompson et al., 2000; Cook & Sheikh, 2003; Linn et al.,

1998; Macpherson et al., 2002) as to the benefits of its use in preventing severe head

injuries, particularly for children. However, helmet use does not prevent the injury from

occurring in the first place and Robinson (2005) suggests that legislating the use of

helmets may actually discourage bicycle use. Infrastructure improvements, such as

39

dedicated bicycle lanes, play an important role in preventing bicycle/vehicle crashes in

three major ways: 1) they are population-based and have a greater impact on more

people than an individual-based intervention; 2) they are passive and do not require

action from the user; and 3) they are implemented with a single action (installation)

versus requiring on-going enforcement (Chipman, 2002). Reynolds et al (2009) reviewed

11 published studies on straightaways (e.g., bike lanes or paths) and found that cycling

infrastructure improvements reduce the risk of crashes and injuries compared to cycling

on-road with traffic or off-road with pedestrians. Lott and Lott (1976) calculated a 53%

reduction in collision frequency in Davis, California streets with marked bike lanes

compared to streets without them. Smith and Walsh (1988) compared crash rates before

and after installation of marked bike lanes in Madison, Wisconsin and found an increase

in collisions during the first year post-installation, particularly for bike lanes located on

the left-side of the street. This might be due, in part, to the ‘newness’ of these changes in

the road usage. Often, cities do little to no education to inform the public about these

kind of changes and how they should respond when driving. Reynolds et al (2009) found

only two published studies on road design (Klop & Khattak, 1999; Allen-Munley et al.,

2004) and suggests that studying other features, such as traffic calming measures, will

help transportation planning officials to better design infrastructure to integrate active

transportation for their communities while keeping non-motorists safe.

E. Traffic Calming Policies

Traffic calming measures include physical changes to roadways to decrease

vehicle speeds. The speed of a vehicle is an important factor in increased risk of severity

of injury to both pedestrians and cyclists. Elvik (2001) performed a meta-analysis of 33

40

studies of traffic calming measures from eight countries on reducing injury collisions and

found that residential streets saws the greatest effect with a 25% reduction in injury

collisions, a 10% reduction on main roads and an overall reduction of 15%. However,

collisions involving pedestrians and cyclists were not studied.

Transportation policy has a significant influence on public health. Research

shows active transportation increases through the provision of infrastructure. This, in

turn, should contribute to an increase in physical activity for residents of these

communities, which over time should lead to a reduction in BMI, obesity rates and

corresponding chronic, lifestyle-related diseases, such as diabetes and heart disease. In

other words, the health of those participating in active transportation could be enhanced

with the implementation of supportive policy. This study will demonstrate if an

association exists between traffic calming and incidence of vehicle collisions with

pedestrians and cyclists.

F. Summary

Current U.S. transportation policy continues to focus on vehicle travel, rather than

a multi-modal approach. This equates to lower participation of pedestrians and cyclists in

safe active transportation. Germany and The Netherlands have demonstrated that policy

can provide infrastructure necessary to make walking and cycling more attractive to

residents. Additionally, various studies demonstrate that infrastructure, such as bike

lanes, can yield three to five times a return on investment in health benefits and reduced

healthcare costs, compared to the cost of installation. Other variables that influence

active transportation include mixed land use, high density of residents and connected

streets and bike lanes. These are characteristics of older neighborhoods, but can be put

41

into place in newer communities with the implementation of policy that supports active

transportation infrastructure.

Research supports active transportation policy. Mixed land use, poverty rate,

traffic volume and lack of designated space for active transportation all have an influence

on vehicle collisions with pedestrians and cyclists. Research on traffic calming policies

has been limited with mixed results. Further study is needed to determine if

implementing traffic calming policies reduces collisions between vehicles and non-

occupants, specifically pedestrians and cyclists.

42

CHAPTER 3

METHODS

A. Study Design

A staggered entry quantitative analysis was used to identify an association

between road diets and pedestrian and cyclist injuries resulting from collisions with

vehicles on road diet-improved streets in Los Angeles, California from 2004 to 2014.

Pedestrian and cyclist injury data were matched with city streets that were improved

through road diets. Injuries occurring before the street improvement year were compared

to injuries after the road diet improvement to determine if road diets had an impact on

pedestrians and cyclists.

1. Setting

The city of Los Angeles is located in the geographic area of southern

California. The Southern California Association of Governments (SCAG) is the largest

metropolitan planning organization in the U.S. which has authority and responsibility for

transportation and community planning for the majority of southern California. City

planning and transportation agencies report to and coordinate with SCAG

(https://www.scag.ca.gov/).

With a land mass of over 38,000 square miles, this geographic area contains

approximately 60% of the state’s population, or 18 million residents. Los Angeles, the

most populous city in the region and the state, is the second largest city in the U.S.

According to the Los Angeles Almanac (http://www.laalmanac.com), Los Angeles

County has 16,785 miles of city streets and a total of 20,771 miles of highways, streets

and roadways. Each day, 92 million vehicle miles are driven on these roads.

43

The city of Los Angeles was selected for this study for the following criteria: 1)

located in an urban city, 2) passed an active transportation policy or resolution within the

last 10 years, 3) implemented lane reductions as a traffic calming measure on more than

50 miles of local surface streets, and 4) collected traffic volume data on the streets within

the city’s jurisdiction.

According to conversations with representatives from southern California

transportation agencies, data of traffic calming measures such as road diets were limited,

if available, due to several factors: 1) limited time since passing of the community

transportation policy (M. Mowery, LA DOT, personal communication, November 10,

2014); 2) lack of reporting policy (J. Gormley, City of Fresno, personal communication,

November 10, 2014; J. Lee, SANBAG, personal communication, October 2, 2014; E.

Lewis, City of Moreno Valley, personal communication, October 13, 2014; A. San

Miguel, SCAG, personal communication, October 2, 2014; D. Moosavi, Cal-Trans, April

7, 2015; J. Raspa, LA DOT, personal communication, April 7, 2015); 3) varied and

limited funding sources (J. Gormley, personal communication, November 10, 2014; E.

Lewis, personal communication, October 13, 2014); 4) lack of coordination among

neighboring cities to increase the length of improved streets (E. Lewis, personal

communication, October 13, 2014; J. Lee, personal communication, October 2, 2014); 5)

varied responsibility and control over streets within a jurisdiction (J. Lee, personal

communication, October 2, 2014; B. Thomas, Cal-Trans, personal communication, April

7, 2015); and 6) the lengthy approval and implementation process for community

transportation policy (J. Gormley, personal communication, November 10, 2014; M.

Mowery, personal communication, November 10, 2014).

44

2. Data

Collision data involving pedestrians and cyclists for the city of Los Angeles were

obtained from the California Statewide Integrated Traffic Records System (SWITRS)

database, a public data set that contains traffic accidents occurring on California

highways, streets and roadways reported by the California Highway Patrol and local law

enforcement, such as police and sheriff departments. Data from the National Highway

Traffic Safety Administration’s Fatality Analysis and Reporting System (FARS) and

General Estimates System (GES) or the Centers for Disease Control and Prevention’s

Web-based Injury Statistics Query and Reporting System (WISQARS) were not used

because they contain only national aggregated data.

Collision victim data were previously de-identified prior to archiving in the

SWITRS database. The only remaining victim information included age, gender and

ethnicity. Other collision-specific information included date and time, primary and

secondary (e.g., cross street) roads, primary collision factor, movement prior to collision,

severity of injury, weather, surface and lighting conditions, and sobriety status of the

victim and driver. Study inclusion criteria were pedestrians and cyclists who were 18

years of age or older and involved in a vehicle collision on a road diet street during the

study period. Adults were selected for this study because they can choose to complete

trips by walking or cycling instead of using their personal vehicles. Children injured in

collisions were presumed to be either playing or traveling to school and were excluded

from this study.

SWITRS defined an injury as a victim experiencing one of the following: 1) pain,

2) a visible injury, 3) a severe injury, or 4) death. Under-reporting of injuries could occur

45

if a pedestrian or cyclist did not report an injury to law enforcement at the time of the

collision. In addition, a collision could produce more than one victim.

Of the southern California cities that were identified as implementing road diets,

the city of Los Angeles was the only jurisdiction to provide detailed street improvement

data and average daily vehicle counts. Los Angeles Department of Transportation (LA

DOT) provided the data to the student investigator. Vehicle collision data involving both

pedestrians and cyclists were obtained from SWITRS for 2004, which is two years prior

to initiation of the street improvement projects in 2006, through 2014, the most recent

complete year of data. Data reports were requested through the SWITRS database and

delivered via email to the student investigator. Table X is a sample of road diets in Los

Angeles and illustrates the staggered pre/post entry design.

Table X: Sample Road Diets in Los Angeles by Location and Year Implemented

Road Diet

Location

Length (miles)

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

York 2.7 Pre Pre I I I Post I

Hoover 0.9 Pre Pre I Post Myra 0.4 Pre Pre I Post Wilbur 1.5 Pre Pre I Post Via Dolce 0.4 Pre Pre I Post

7th Street 2.8 Pre Pre I I Post

Spring Street 1.4 Pre Pre I Post

46

RoadSafe GIS was accessed on the website (www.roadsafegis.com) that

contained geo-coded SWITRS traffic collision data for the city of Los Angeles along

with a data dictionary describing the data fields. RoadSafe GIS matched approximately

93% of the SWITRS collisions to streets with minimal errors due to comprehensive

manual reviews. The remaining 7% of collisions were not geocoded to streets because of

lack of specificity in the initial incident report. Collisions and corresponding injuries

were matched to city streets using the primary and secondary streets and geocoded on the

GIS street map.

3. Methods

GIS (ESRI ArcMAP, v. 10.3.1) was used to store, manipulate and map injuries

and road diet-improved street segments. Based on the data obtained from the LA DOT,

road diets were installed on 53 streets within the city of Los Angeles between the years of

2006 and 2014, with a total of 51.9 miles of street improvements. SWITRS collision data

were not available for 2015 due to the length of time needed for data verification and

entry. Therefore, 7.7 miles of road diets installed in 2014 were excluded from this study

and the remaining 44 streets with 44.2 miles of road diet street segments were included in

the analysis. See Appendix X for the complete list of road diets in Los Angeles for this

study period.

Collision events and resulting injuries that occurred on road diet-improved street

segments during the study years 2004 to 2014 were isolated from the SWITRS data.

From this data set, adult pedestrian and adult cyclist injuries were selected.

Injuries before and after road diet implementation were compared for three

groups: pedestrians, cyclists and both groups combined. A staggered pre/post entry

47

design was applied for this study and was based on the differences in years that the road

diets were implemented.

4. Data Analysis

Injuries were adjusted by year and mile of road diet. The average of two years of

injuries prior to the implementation of the road diet was used for each street segment to

generate more reliable data. Due to the lack of 2015 SWITRS data, only one year of

injuries could be applied after the road diet implementation. The year after

implementation was used to compare injuries to the average of the previous years of data.

In addition, injuries were adjusted per mile of road diet, based on the length of the

improvement identified by LA DOT.

A paired t-test was used to determine whether the mean number of injuries to

pedestrians, cyclists and pedestrians and cyclists combined was the same before and after

installation of road diets on Los Angeles streets. The null hypothesis (Ho = 0) assumes

there was no statistical difference in the number of pedestrian and cyclist injuries

between the pre and post road diet installation years of the study, 2004-2014. SPSS

(IBM SPSS Statistics, Version 23) was used to calculate the paired t-tests for the three

groups of injuries. The level of significance for this study was set at p = 0.05.

Assumptions for normality of the dependent variable were assessed which revealed

somewhat normal distribution. Since the paired t-test compares the means of injuries

per mile, the results can be highly influenced by outliers. Therefore, square root

transformation was applied resulting in a better fit for normality.

48

Traffic volume was previously identified in the literature as an important variable

influencing the number of collisions. Therefore, traffic volume in the form of average

daily traffic counts were identified from two sources. The first source was the LA DOT,

which provided the student investigator with this data for the period of 2001-2013.

Google Earth Pro (Source: Kalibrate Technologies, http://www.kalibrate.com/) was the

second source which was used to obtain additional traffic counts to supplement the data

from the LA DOT. These figures were either physically counted with a device at the

street level or modeled with traffic engineering software. Including both data sources

allowed greater sensitivity, particularly since some streets did not have traffic counts

from one source. This data were mapped using GIS and matched to road diet streets.

However, traffic volume data recorded both before and after road diet improvements

were only available for three street segments. Therefore, traffic volume was not used due

to lack of sufficient counts.

5. Data Management

Data used in this study was maintained on the LLU School of Public Health

server with access granted by the school’s information systems director. Access was

granted to the student investigator, committee members and two consultants who

were employees of the institution.

B. Strengths and Limitations

1. Strengths

This was the first study to examine road diets and impact of collisions

between vehicles and non-occupants of pedestrians and cyclists. While the street and

injury data came from a single city, the statistical analysis revealed a negative association

49

with road diets and injuries to pedestrians and cyclists. This information is applicable to

other urban cities by providing funding support for more road diets and can pave the way

for more research in this area.

Triangulation of data from SWITRS, RoadSafe GIS and LA DOT allowed

verification and confirmation of numbers of injuries and locations of road diets.

Finally, the informal interviews of transportation officials conducted by the

student investigator formed connections and allowed a better understanding of

transportation policy process and funding mechanisms.

2. Limitations

Analysis of one urban city, Los Angeles, was included in this study. Other cities

have started to implement road diets, but only a small distance of streets have been

completed, such as the city of Moreno Valley, which completed three miles (E. Lewis,

personal communication, October 13, 2014).

The analysis was changed to include more street segments. Originally, the

analysis called for averaging collision data for two years both pre and post road diet

implementation. However, this analysis would have reduced the total miles of street

segments included in this study to less than 6 miles, eliminating most of the road diets.

Changing the analysis allowed more street segments to be included. However, the post-

improvement injury data was only one year which could have created a false increase in

injuries due to the novelty of the road diet.

Traffic volume was initially included in this study to evaluate the impact of

number of vehicles to pedestrian and cyclist injuries. However, consistent, valid,

historical data was not available due to lack of collection standards and routine collection

50

schedule. These restrictions were also true for pedestrian and cyclist counts which were

not available prior to 2009 due to a lack of data collection standards and tool and a

database to store and disseminate the pedestrian and cyclist counts.

C. Research Ethics

The Institutional Review Board’s (IRB) approval was obtained on September 18,

2015, prior to the start of this study, through a Notice of Determination of Human Subject

Research. This document shows that the proposed research did not meet the definition of

human subjects’ research. Nevertheless, confidentiality of all data was strictly

maintained.

51

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APPENDIX A

LLU Institutional Review Board

Notice of Determination of Human Subjects Research

September 18, 2015

66

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APPENDIX B

Data Set of Road Diets in Los Angeles

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