Evaluating pedestrian crashes in areas with high low-income or minority populations

Abstract

In this paper, we present an analysis of the relationship between pedestrian–vehicle crashes and characteristics of areas with high low-income and minority populations in the Chicago metropolitan area (also called environmental justice or EJ areas in the United States). While related research has indicated that pedestrian crashes occur more frequently in these areas than in non-EJ areas, this paper attempts to relate the incidence to environmental characteristics and behavioral factors through a better understanding of the contributing factors present in crash occurrences in EJ versus non-EJ areas. Specially constructed small-area factors from a Spatial Decision Support System (SDSS) are used to explain pedestrian–vehicle crashes.

Using a Poisson model that corrects for underreporting, we find that pedestrian crash incidents in EJ areas are related to variables of exposure (including the suitability of the area for walking and transit accessibility), crime rates, transit availability, and general population demographics such as income and presence of children. Results suggest that it may be necessary to better incorporate a safety perspective or measures of safety improvements in pedestrian and transit improvements and expansion programs within EJ areas.

Introduction

In 2005, motor-vehicle crashes killed 4881 pedestrians in traffic in the United States and sent 120,815 pedestrians to emergency medical departments (National Highway Traffic Safety Administration [NHTSA], 2006). While the contributing causal factors to these crashes vary widely, previous studies have indicated that certain factors relating to the socio-demographics and the physical environment of neighborhoods may heighten the risk of pedestrian–vehicle crashes. These initial indications are particularly relevant in regards to environmental justice (EJ) guidelines which broadly require each U.S. federal agency to make the alleviation of inequitable environmental burden a part of its mission by identifying and addressing, as appropriate, disproportionately high and adverse human health or environmental effects of its programs, policies, and activities on minority and low-income populations (Environmental Protection Agency, EPA, Executive Order, 1994). This paper is intended to specifically address pedestrian–vehicle crashes within the framework of EJ guidance to determine if pedestrian safety is an issue that should be specifically addressed within EJ activities.

Several authors have noted that there is an increased incidence of pedestrian–vehicle crashes in EJ areas (Mid-America Regional Council, 2007, Murtha, 2005). EJ areas are those with high proportions of minority and low-income households (the specific definition used in this paper is given in Section 3.1). While numbers gathered from these evaluations are of interest, what is notable is that occurrences of crashes are often cited while paying little attention to the question of general exposure to risk, including such factors as mixture of land uses, the number of potential pedestrians in an area, or the overall character of the surrounding environment and whether it is inviting to and safe for pedestrian travel.

The current study more extensively explores some geographic correlates of pedestrian–vehicle crashes, through an analysis of data from the Chicago metropolitan area in the State of Illinois, USA, with particular emphasis on spatial variations on these events by EJ versus non-EJ area. We examine 2005 Chicago vehicle–pedestrian crash data, gathered from the Illinois Department of Transportation (IDOT) as a case study in order to hold factors beyond socio-demographics constant and to provide information relating to risk levels in environmental justice areas. Statistical evidence, as presented below, shows that an elevated risk is present, perhaps indicating that policies and programs addressing pedestrian–vehicle crashes in these areas should be targeted to those factors that are likely to account for such increases in risk.

The objective of the paper is to report on a comparative analysis of motor-vehicle–pedestrian crashes in EJ versus non-EJ areas and to understand which factors contribute to variations in pedestrian crashes in those areas. We have taken the view that two groups of geographic factors can potentially affect observed differences – those relating to the physical environment (called environmental factors) of the areas and those relating to social behaviors, cognitive and demographics (called behavioral factors) of the residents of the areas. These measures are a part of an ongoing research project to develop a Spatial Decision Support System on the Chicago metro area for planning purposes by the authors’ research team. The construction and potential use of these measures in accident analysis are described. The importance of these factors in explaining EJ versus non-EJ differences in pedestrian crashes are demonstrated using exploratory methods as well as regression. An issue of concern that is addressed in the paper is underreporting of pedestrian crashes – we have adopted a statistical approach to address potential underreporting in the Chicago vehicle–pedestrian crash data.

The paper is organized as follows: prior literature on environmental justice and pedestrian crashes is reviewed in Section 2. The study area, the method by which EJ areas were determined and the environmental and behavioral factors considered are presented in Section 3. Section 4 presents an exploratory analysis of crash trends in EJ versus non-EJ areas and reports summary statistics on the factors and on crash patterns in the two types of areas. Statistical models of pedestrian crashes are given in Section 5. Summary and conclusions are drawn in Section 6.