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Open Access Publications from the University of California

Estimating Pedestrian Accident Exposure: Protocol Report


Walking is a healthful, environmentally benign form of travel, and is the most basic

form of human mobility. Walking trips account for more than 8 percent of all trips

taken in California, making walking the second most commonly used mode of travel

after the personal automobile (Caltrans, 2002). In addition, many trips made by

vehicle or public transit begin and end with walking.

In spite of the importance and benefits of walking, pedestrians suffer a

disproportionate share of the harm of traffic incidents in California. As noted above,

walking trips make up just 8 percent of all trips in the state, but 17 percent of all

traffic fatalities are suffered by pedestrians. In 2004, 694 pedestrians were killed in

the state of California and 13,892 were injured (California Highway Patrol, 2004).

To address this problem, significant resources are focused on countermeasures that

aim to reduce the risk of pedestrian injury. Because resources are limited, risk

analysis is necessary to develop cost-effective countermeasures (Hoj and Kroger,


In the field of pedestrian safety, risk analysis involves assessing factors that

contribute to the danger that a pedestrian is struck by a vehicle. These factors may

include physical characteristics of the street, such as lack of sidewalks; behavioral

issues, such as pedestrian or driver alcohol use; as well as other environmental

variables. In order to fully understand how these factors contribute to risk, it is

necessary to collect information on pedestrian exposure. Collection of pedestrian

exposure information is an essential component of risk analysis.

Pedestrian exposure is a concept that refers to the amount that people are exposed

to the risk of being involved in a traffic collision. In principle, pedestrians are exposed

to this risk whenever they are walking in the vicinity of automobiles. There are many

metrics that can be used to measure pedestrian exposure, but pedestrian volumes

are the most frequently used.

Although many state, regional, and local agencies have developed methodologies to

collect pedestrian volume data, there is no consensus on which method is best

(Schneider et al., 2005; Schweizer, 2005). This is because there is no “one size fits

all” method of counting pedestrians. Rather, the choice of strategy depends on a

complex range of factors, including the characteristics of the area being studied; the

resources available for data collection; and the specific purpose of data collection.

This protocol aims to improve pedestrian data collection in the state of California by

providing information and guidance for each decision point in the data collection

process. Each chapter represents one of these decision points, and each will guide

the user through important considerations relevant to the data collection stage. In

addition, each chapter provides a combination of real-world and hypothetical

example scenarios to illustrate the issues discussed in the text.

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