National Academies Press: OpenBook

Systemic Pedestrian Safety Analysis (2018)

Chapter:Chapter 1 - Introduction to Purpose and Process of Systemic Analysis

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Suggested Citation:"Chapter 1 - Introduction to Purpose and Process of Systemic Analysis." National Academies of Sciences, Engineering, and Medicine. 2018. Systemic Pedestrian Safety Analysis. Washington, DC: The National Academies Press. doi: 10.17226/25255.
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Suggested Citation:"Chapter 1 - Introduction to Purpose and Process of Systemic Analysis." National Academies of Sciences, Engineering, and Medicine. 2018. Systemic Pedestrian Safety Analysis. Washington, DC: The National Academies Press. doi: 10.17226/25255.
Page 5
Suggested Citation:"Chapter 1 - Introduction to Purpose and Process of Systemic Analysis." National Academies of Sciences, Engineering, and Medicine. 2018. Systemic Pedestrian Safety Analysis. Washington, DC: The National Academies Press. doi: 10.17226/25255.
Page 6
Suggested Citation:"Chapter 1 - Introduction to Purpose and Process of Systemic Analysis." National Academies of Sciences, Engineering, and Medicine. 2018. Systemic Pedestrian Safety Analysis. Washington, DC: The National Academies Press. doi: 10.17226/25255.
Page 7
Suggested Citation:"Chapter 1 - Introduction to Purpose and Process of Systemic Analysis." National Academies of Sciences, Engineering, and Medicine. 2018. Systemic Pedestrian Safety Analysis. Washington, DC: The National Academies Press. doi: 10.17226/25255.

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3 In the United States, while motor vehicle occupant safety has made considerable strides, pedes- trian fatalities are on the rise, making up a greater and greater portion of all traffic fatalities each year (see Figure 1). Figure 1 is based on the Fatality Analysis Reporting System or FARS data from the National Highway Traffic Safety Administration; see fatality-analysis-reporting-system-fars. In 2016 alone, 5,987 pedestrians were killed in collisions with motor vehicles (Retting 2018), making it the deadliest and costliest year for pedestrians in the United States in more than 25 years. In more urban states and cities, pedestrian crashes can represent as much as 25 to 45% of all traffic fatalities (Williams 2015). Addressing pedestrian safety issues and curbing this trend have become a twofold critical mis- sion for both state and local transportation agencies. Essentials of a Systemic Approach Constrained resources, a perennial challenge for state and local transportation agencies, have motivated many to seek more innovative and data-driven methods to use limited transportation funds in ways that maximize cost-effectiveness and safety impact. In recent years, many states have adopted systemic approaches to safety, which, according to the Federal Highway Safety Administration [(FHWA),], “helps agencies broaden their traffic safety efforts at little extra cost.” The basic tenets of a systemic safety approach, as outlined in FHWA’s Systemic Safety Project Selection Tool (Preston et al. 2013), are as follows: • Identifies a safety concern based on an evaluation of data at the system level. • Establishes common characteristics (risk factors) of locations where severe crashes frequently occur. • Emphasizes deploying one or more countermeasures to address the underlying circumstances at many of the locations experiencing the risk factors. • Given high aggregate numbers of target crashes but low average density per site, tends to deploy lower cost countermeasures to many sites to affect a large number of locations. Motivation for a Systemic Approach FHWA maintains a website resource that catalogs the practices of states that are taking a systemic approach that is available at At the time of this publication, nearly a dozen states and a handful of cities and regions are implementing C H A P T E R 1 Introduction to Purpose and Process of Systemic Analysis

4 Systemic Pedestrian Safety Analysis systemic approaches to safety. Although few have focused on pedestrian issues, lessons from places that are implementing systemic safety approaches are consistent. The benefits of a sys- temic approach are: • Stronger basis for decisions: Accounts for important factors, such as activity/exposure and randomness that are often excluded from a traditional crash “hot spot” approach when identifying locations for improvement. • Effective use of resources: Helps focus resources on crash risks that are most prevalent across the network and guides selection of appropriate treatments and locations to reduce the most serious crashes. • Data-driven approach: Provides a data-driven/analytical method and screening tools that can be used to justify funding decisions, even if there is not a specific crash history at a given loca- tion. A data-driven process also creates new opportunities to provide an equitable risk-based assessment across a jurisdiction. • More proactive approach: Takes a forward-looking approach to address safety issues without waiting for a crash history to develop at any given location. • Consistency: Helps avoid dealing with broad safety issues one project at a time and instead treats risks more widely and consistently. Ultimately, a systemic approach is intended to lead to more informed decision making and optimized investment, which will result in accelerated safety improvements. Definition: Systemic Approach A systemic approach is a data-driven, networkwide (or system-level) approach to identifying and treating high risk roadway features correlated with specific or severe crash types. Systemic approaches seek to not only address locations with prior crash occurrence but also those locations with similar roadway or environmental crash risk characteristics. A systemic approach resides on a spectrum of ways that transportation agencies may address safety issues (see Figure 2) and is considered a more proactive approach than those that focus only on treating specific locations with a crash history. 40K 30K 20K 10K 0 8K 6K 4K 5K 0 Figure 1. U.S. motor vehicle and pedestrian fatalities between 1997 and 2016. Data cover 20 years; tick marks indicate 3-year intervals plus 2016.

Figure 2. A systemic approach addresses sites with similar risk factors, regardless of crash history. The approach falls along a spectrum of other approaches to safety that are more or less proactive in treating sites based on risk or prior crash history.

6 Systemic Pedestrian Safety Analysis Steps in a Systemic Pedestrian Safety Analysis Process As outlined in this guidebook, there are seven key steps in a systemic pedestrian safety analysis process (see Figure 3). While the steps are presented in a linear sequence, some of these steps may occur simultaneously, in different orders, or iteratively, and there is wide latitude for agencies to enter the process at different points. Noteworthy Practice In 2001, the City of Seattle Department of Transportation (Seattle DOT) identified the need for improvements to pedestrian crossings throughout the city. Crash data had shown that pedestrian crashes accounted for roughly 25% of all fatal crashes in the city, and there were signs that number could rise as pedestrian activity increased. Seattle DOT wanted to take a more proactive and comprehensive approach to address risks across the network rather than only responding to a site after a crash occurred. At that time, there were not a lot of examples of how to go about conducting a systemic pedestrian safety study. An early effort involved inventorying and assessing all unsignalized crosswalk locations using risks identified from a national study. The City has recently invested in data improvements and robust, systemic pedestrian safety analyses. Their experience led the way for the development of many of the processes and methodologies presented in this guidebook. See Case Example 1 for further details. Figure 3. Steps in a systemic pedestrian safety analysis process.

Introduction to Purpose and Process of Systemic Analysis 7 The steps highlighted in Figure 3 include the following: Step 1 involves defining the area for analysis, identifying the facility or location type target or focus, and identifying subsets of target crash type(s) for systemic focus. This step sets the stage for all subsequent steps. Step 2 involves compiling the roadway and other location characteristics and crash data that will be needed to identify risk factors in Step 3. All systemic processes require data, and the compiled data will serve as an important foundational database to identify potential treat- ment sites in Step 4. Step 3 involves analyzing data to determine factors associated with the target pedestrian crash type or location of interest or using alternate approaches from research or local knowledge to identify key risk factors. Step 4 involves identifying an optimal set of sites that have common risk and site characteristics that are suitable for similar packages of treatments, using various screening and ranking methods. Step 5 involves identifying appropriate countermeasures or combinations of measures that could potentially address risks identified. In Step 5, there is also a chance to further refine and pri- oritize the locations identified in Step 4. Step 6 involves considering additional priorities, performing diagnostics, performing economic assessments, allocating funding, and implementing a systemic treatment plan, including construction of pedestrian safety improvements. Step 7 involves evaluating project and program impacts before starting the process anew. A systemic process is fundamentally a data-driven process, so a theme throughout this guide- book relates to how and why agencies can make data current and complete, accessible, central- ized, and linked to support more robust pedestrian safety analysis and implementation. Agencies familiar with FHWA’s Systemic Safety Project Selection Tool (Preston et al. 2013) will recognize many of the same activities, often in a similar sequence. The process detailed in this guidebook builds on FHWA’s established process, but because of the unique needs of pedes- trians in terms of crash risks, effective countermeasures, and available data, it provides guidance on key additional steps needed to successfully perform a systemic risk-based analysis focusing on pedestrian safety. A key question that readers may ask is “How can this process be incorporated into my agency’s highway safety management process?” This process was designed to be highly compatible with the Highway Safety Manual (HSM) safety management process, which is used in some form by many DOTs (AASHTO 2010). Table 1 indicates which steps in this guide may be most similar to different phases of the HSM process. The following chapters provide in-depth guidance on how to successfully perform systemic pedestrian safety analyses and weave such processes into a broader safety management program. If you are in the HSM process… Find guidance for incorporating a systemic approach in… Prior analysis (not shown in HSM’s six steps) Steps 1–3 Network screening Step 4 Diagnosis Step 1 (section on identifying one or more target locations and crash types in Chapter 2), Step 3, Step 6 (section on performing additional diagnostics in Chapter 7) Select countermeasures Step 5 Economic appraisal Step 6 (section on performing economic assessments in Chapter 7) Prioritize projects Step 6 Evaluate Step 7 Table 1. Relation of the pedestrian systemic process to the Highway Safety Manual process.

Next: Chapter 2 - Step 1: Define Study Scope »
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TRB's National Cooperative Highway Research Program (NCHRP) Research Report 893: Systemic Pedestrian Safety Analysis provides a safety analysis method that can be used to proactively identify sites for potential safety improvements based on specific risk factors for pedestrians. A systemic approach, as opposed to a “hot-spot” approach, enables transportation agencies to identify, prioritize, and select appropriate countermeasures for locations with a high risk of pedestrian-related crashes, even when crash occurrence data are sparse. The guidebook also provides important insights for the improvement of data collection and data management to better support systemic safety analyses.

The Contractor's Final Technical Report and a PowerPoint presentation summarizing the project accompany the report.

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