Safety Analysis Methods & Resources


Based on Historic Crashes and Trends

Location Specific AnalysisLocation specific Analysis

Specific location safety analysis determined by:

  • Where there is a high number of crashes
  • Where there are high crash rates
  • Where there are fatalities/serious injuries
  • Where systemic analysis has identified as a location of focus
  • Conducting crash report analysis

 

 

 

Systemic Analysissystemic

Broader network analysis of data to determine where safety improvements are needed:

  • Identifies characteristics that frequently contribute to certain crash types
  • Focuses on countermeasures that can be deployed widely across the system
  • Identifies and prioritizes locations across the network for implementation

 

 

 

Based on Safety Performance

Predictive Analysispredictive

Risk based approach to systemically analyze safety performance of roadways:

  • Uses risk factors to identify locations to implement safety improvements to prevent crashes
  • Safety Performance Functions (SPFS) are developed from crash data from similar sites, all adjusted to presumed "base" conditions
  • Crash Modification Factors (CMFs) are then applied to convert from the base conditions to the conditions at the location being studied
  • A local calibration factor is also applied based on local crash experience on similar roadway sites
  • Empirical methods may also be applied if both a SPF and actual crash data are available
  • Crash Reduction Factors (CRFs) and relationship to CMFs

Click here to access Safety Data Analysis and Mapping tools.

data analysis

 

HSM

 

 

AASHTO’s Highway Safety Manual (HSM) is the guidance document for incorporating quantitative safety analysis in the highway transportation project planning and development processes to inform the highway transportation decision-making process. 

 

The HSM includes guidance on:

  • Human factors and the fundamentals of traffic safety
  • The roadway safety management process (including information relevant to FHWA’s Highway Safety Improvement Program requirements and project planning), including:
    • Network screening (identify sites with potential for crash or severity reduction
    • Site assessment (diagnosis, countermeasure selection, economic appraisal
    • Project prioritization
    • Safety effectiveness evaluation
  • Predictive methods for infrastructure improvement project alternative analysis and development/design, including:
    • Use of national safety performance functions (models) developed to predict crashes by severity specific facility types and base conditions
    • Associated crash modification factors (CMFs) to estimate the potential effects of design alternatives or changes from base conditions

 

AASHTO Safety Analysis Resources:
Highway Safety Manual -Includes News, Brochures, Spreadsheets, Webinar Recordings, and Other Materials
AASHTO HSM Tools
Safety Performance for Intersection Control Evaluation (SPICE) Tool
Interactive Highway Safety Design Model (IHSDM)


Transportation Research Board Safety Analysis Resources:
Highway Safety Manual Data Needs Guide

FHWA Safety Analysis Resources:
CMF Clearinghouse


FDOT Safety Analysis Resources:
Crash Reduction Factors
Map Based Query Tool Code Definitions
Safety Analysis Matrix 
FDOT Highway Safety Manual User Guide 2015
FDOT HSM Implementation Summary
FDOT HSM Implementation Plan Timeline

 

Thank you to FDOT District One for portions of this page content, adapted from the Safety Academy.

 

Page updated : February 10,2021