Enhancing and Generalizing the Two-Level Screening Approach Incorporating the Highway Safety Manual (HSM) Methods, Phase 2

This project aims at developing a novel methodology to identify traffic safety hotspots and hot zones at the macroscopic and microscopic levels. In order to achieve these objectives, the following tasks were performed. The research team followed the Highway Safety Manual (HSM) screening procedure and extended it to the macroscopic level. TAZs (Traffic analysis zones) have been most widely used as a spatial unit for macroscopic analysis; however, TAZs have two disadvantages: small size in urban areas and high percentage of zonal boundary crashes. Thus, the authors have suggested two ways to overcome this issue. The first way is to develop a new study unit – Traffic safety analysis zones (TSAZs), created by aggregating existing TAZs with similar crash rates. The second way is to apply a larger geographic unit such as TADs (Traffic analysis districts) or counties. The authors explored traffic safety not for TAZs only but also for TSAZs, TADs, and counties. The research team developed a series of SPFs (Safety performance functions) both at the macro-level and micro-level for 17 crash types. At the macro-level, overall, 204 SPFs were developed based on SWTAZs (Statewide TAZs), TSAZs, TADs, and counties. The research team has found various contributing factors for each traffic crash type at the macro-level. At the micro-level, overall, 404 Florida-specific SPFs were estimated for 13 segments and 16 intersection facility types. Before the research team proceeded to the screening analysis, the authors performed a grid structure analysis to identify the best geographic units. The results showed that SWTAZs are the optimal zone system for analyzing non-motorized crashes such as pedestrian and bicycle crashes. On the other hand, TADs are found to be the best geographic unit for all other crash types. Subsequently, screening analysis was conducted at the two-levels using PSI (Potential for Safety Improvement) and ranked. Two stage screening could be suggested as a simple way to identify high risk locations. The screening results from the two-levels were integrated, and all the results were provided in Excel spreadsheets for the convenient application of practitioners. It is intended that the results of the project would provide a comprehensive perspective on appropriate traffic safety plans and help practitioners screen and rank any area, segment, or intersection in the state.


  • English

Media Info

  • Media Type: Digital/other
  • Features: Appendices; Figures; Maps; References; Tables;
  • Pagination: 428p

Subject/Index Terms

Filing Info

  • Accession Number: 01600195
  • Record Type: Publication
  • Contract Numbers: BDV24-977-06
  • Created Date: May 20 2016 2:23PM