U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000


Skip to content U.S. Department of Transportation/Federal Highway AdministrationU.S. Department of Transportation/Federal Highway Administration

Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations

IHSDM: Overview | FAQ | Modules | Library | Software Download | Technical Support | Training Course | Related Initiatives | Contacts

 

 

Interactive Highway Safety Design Model (IHSDM): Related Initiatives

 

Two related initiatives share IHSDM’s goal of providing quantitative safety analysis tools to decisionmakers:

  • Highway Safety Manual (HSM).
  • SafetyAnalyst.

 

The Highway Safety Manual is a Transportation Research Board (TRB) and American Association of State Highway and Transportation Officials (AASHTO) initiative (published by AASHTO) to provide the best factual information and tools in a useful and widely accepted form and to facilitate roadway design and operational decisions based upon explicit consideration of their safety consequences. The HSM is organized into four parts:

  1. Introduction and Fundamentals.
  2. Roadway Safety Management Process.
  3. Predictive Methods (see table below comparing HSM and IHSDM).
  4. Crash Modification Factors.

 

The following table compares the types of predictive methods and types of facilities targeted by the HSM and IHSDM. The first edition of the HSM, published in June 2010, provides predictive methods for rural two-lane highways, rural multilane highways, and urban and suburban arterials (with five lanes or fewer). With the 2009 Crash Prediction Module Beta Release (June 30, 2009), Federal Highway Administration (FHWA) expanded the scope of IHSDM to include the HSM crash prediction methods for multilane rural highways and urban and suburban arterials (with five lanes or fewer). The Crash Prediction Module of the IHSDM – HSM Predictive Method 2016 Release is a faithful software implementation of Part C of the First Edition HSM, containing predictive methods for rural two-lane highways, rural multilane highways, and urban and suburban arterials. In addition, the 2016 Release includes predictive methods for freeway segments and freeway ramps/interchanges (including ramps, collector-distributor (C-D) roads, and ramp terminals), based on the HSM 2014 Supplement. Crash prediction methods for 6+ lanes and 1-way urban/suburban arterials were added to IHSDM in 2016, based on materials developed under NCHRP Project 17-58, for inclusion in the future Second Edition HSM. A Calibration Utility assists agencies in implementing the calibration procedures described in the Appendix to Part C of the HSM.

 

Facility Type IHSDM Evaluation Modules
Policy Review Crash Prediction Diagnostic*
Two-Lane Rural Highway IHSDM (2003) IHSDM (2003)
HSM (2010)
IHSDM (2003)
Multilane Rural Highway IHSDM (2015)  IHSDM (2009)
HSM (2010)
 
Urban and Suburban Arterial
(5 lanes or fewer)
  IHSDM (2009)
HSM (2010)
 
Urban and Suburban Arterial
(6+ lanes and 1-way)
  IHSDM (2016)  
Freeway Segments   IHSDM (2012)
HSM (2014)
 
Freeway Ramps/Interchanges   IHSDM (2013)
HSM (2014)
 

 

* Design Consistency, Traffic Analysis, Intersection Review, and Driver/Vehicle Modules

The SafetyAnalyst was developed by FHWA and is now an AASHTOWare product. It provides state-of-the art analytical tools for use in the decision-making process to identify and manage a systemwide program of site-specific improvements to enhance highway safety by cost-effective means. The SafetyAnalyst includes tools for:

  • Network screening
  • Diagnosis and countermeasure selection
  • Economic appraisal and priority ranking
  • Evaluation of implemented improvements

 

The following table compares the scope and type of decisions targeted by the SafetyAnalyst and IHSDM.

  Safety Analyst IHSDM
Scope Network-Level Project-Level
Target Project Selection Decisions Geometric Design Decisions

 

Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000
Turner-Fairbank Highway Research Center | 6300 Georgetown Pike | McLean, VA | 22101