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FHWA Home / Safety / Transportation Safety Planning (TSP) / Transportation Safety Planning (TSP)

Transportation Safety Planning (TSP)

Graphical header that has the title: Applying Safety Data and Analysis to Performance-Based Transportation Planning.

Appendix B. Safety Analysis Objectives and Methods

Table B.1 Safety Analysis Categories, Questions, Tools, and Data Needs
Analysis Category Safety Analysis Question What tools are available? Data Needs
Benchmarking
  • How many fatalities and serious injuries are occurring in my area?
  • How does this compare to other areas or my State?
  • Descriptive Statistics
  • FARS data
  • Total crashes
  • Total fatalities and serious injuries
  • High-level roadway data—roadway ownership, functional classification
  • Agency geographic boundary information
Identify Crash Trends and Contributing Factors
  • Who is involved in crashes?
  • When are the crashes occurring?
  • What are the major contributing factors to crashes?
  • Descriptive Statistics
  • Trend analysis
  • Crash severity—fatality, injury type, property damage, only
  • Crash incidence data—time of day, day, month, weather, etc.
  • Crash type—road departure, intersection, head-on, angle, etc.
  • Contributing factors—age, impairment, seatbelt usage, speed, etc.
Identify and Evaluate Focus Crash Types
  • What are the most common crash types?
  • What are the most common contributing factors?
  • What are the characteristics of the overrepresentation?
  • Descriptive Statistics
  • GIS Mapping
  • Scatterplot
  • Overrepresentation
  • Risk Ratio
  • Crash severity—fatality, injury type, property damage, only
  • Crash incidence data—time of day, day, month, weather, etc.
  • Crash type—road departure, intersection, head-on, angle, etc.
  • Contributing factors—age, impairment, seatbelt usage, speed, etc.
Network Screening—Identify Sites for Safety Improvement
  • What locations (intersections or segments) show the most potential for safety improvements?
  • AASHTO HSM Part B Network Screening—Includes descriptive and predictive methods
  • AASHTOWare Safety AnalystTM
  • GIS Heat Mapping
  • Crash severity
  • Crash location
  • Roadway and roadside characteristics—intersection control, number of lanes, presence and type of shoulder, presence and type of median, posted speed, horizontal and vertical alignment, etc.
  • Traffic volume data—intersection total entering traffic volume, roadway segment volume per million vehicle miles
  • Calibrated safety performance functions, if predictive methods are used
Systemic Analysis—Identify Safety Risk Factors
  • What are the common characteristics of locations with crashes?
  • What are the countermeasures to address these characteristics?
  • How should we prioritize systemwide implementation?
  • FHWA Systemic Safety Project Selection Tool
  • Crash severity
  • Crash location
  • Roadway and roadside characteristics—intersection control, number of lanes, presence and type of shoulder, presence and type of median, posted speed, horizontal and vertical alignment, etc.
  • Traffic volume data—intersection total entering traffic volume, roadway segment volume per million vehicle miles
Corridor and Intersection Planning Safety Analysis
  • What are the safety effects of alternative roadway or intersection cross sections?
  • AASHTO HSM Part C Predictive Method and NCHRP 17-38 Spreadsheets
  • Interactive Highway Safety Design Model (IHSDM)
  • Crash Modification Factors (e.g., FHWA Crash Modification Factor Clearinghouse)
  • Collision Diagrams
  • Crash severity
  • Crash location
  • Roadway and roadside characteristics—intersection control, number of lanes, presence and type of shoulder, presence and type of median, posted speed, horizontal and vertical alignment, etc.
  • Traffic volume data—intersection total entering traffic volume, roadway segment volume per million vehicle miles
  • Calibrated safety performance functions if predictive methods are used

<< Appendix A       Appendix C >>

Page last modified on December 11, 2015
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