Systemic Pedestrian Safety Analysis (2018) / Chapter Skim
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Pages 25-34
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From page 25... ...
25 The purpose of this step is to identify treatable crash risk factors that can be used to identify locations across the network for potential systemic treatments. Using the database developed in Step 2, the next step is to analyze the data to identify factors associated with the focus pedestrian crash types.
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From page 26... ...
26 Systemic Pedestrian Safety Analysis these challenges and to produce reliable estimates of crash potential that could be used to prioritize locations for treatment. In a nutshell, the HSM recommends the development of model equations known as safety performance functions (SPFs; a definition is provided in the Glossary and in Step 2)
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From page 27... ...
Step 3: Determine Risk Factors 27 Risk Determination from Crash Count Models of Jurisdictional Data: SPF Method Developing SPFs by use of negative binomial regression modeling has been widely used and tested and is a defensible method to model the relationship of variables to crash frequencies. Other analysis approaches are also available to perform predictive modeling of crash frequencies.
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Table 6. Comparison of methods for determining risks to use in a systemic pedestrian safety process.
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From page 29... ...
Step 3: Determine Risk Factors 29 to determine risks. The other two methods are determining risk factors from a combination of prior research and local knowledge and using systemwide crash data to identify locations in the network where target crash types have occurred and the prevalent characteristics of those locations.
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30 Systemic Pedestrian Safety Analysis Table 8 summarizes conditions associated with increasing pedestrian injury severity. In general, the evidence for some of these measures associations with pedestrian or crash injury severity are quite strong, as there have been many crash-based studies analyzing relative severity outcomes.
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Step 3: Determine Risk Factors 31 crash types have occurred and then to identify prevalent characteristics of those locations. This method is basically an extension of the crash tree or matrix methods used initially to identify focus crash types in Step 1.
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32 Systemic Pedestrian Safety Analysis Perform Analyses and Identify Risk Factors If an agency is analyzing network data (developing SPFs or performing another type of modeling or analysis) , this step describes a few considerations for performing those analyses.
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Step 3: Determine Risk Factors 33 likely to occur. These crash estimates raise the priority of those sites for further treatment consideration.
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From page 34... ...
34 Systemic Pedestrian Safety Analysis • One-way traffic flow • Presence of right-turn only lanes at an adjacent intersection Steps 4, 5, and 6 will build on these results to demonstrate how these variables could be used to identify potential treatment sites and countermeasures and to prioritize systemic safety projects using economic analyses. Additional Resources Case Example 1 in this guidebook and Chapters 3 and 4 in the technical report provide more information and a detailed example analysis using the SPF development method.
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