Overview

Background

• What Is the Highway Safety Manual, and Why Was It Developed?
• Where Can I Find an Overview of the HSM?
• Is the HSM Required?
• Who is The Targeted User of the HSM?
• How Is the Highway Safety Manual Related to the AASHTO Green Book and Roadside Design Guide?
• How Is the Highway Safety Manual Related to the Manual of Uniform Traffic Control Devices?
• How Is the Highway Safety Manual Related to the Human Factors Guidelines for Roadway Systems?
• Where can I find information on Guidelines for Crash Testing Safety Hardware?
• What are the types of safety and operational analytical tools that can be used in Performance Based Practical Design (PBPD)? What tools would be appropriate?
• Can a State Department of Transportation Use Federal Highway Safety Improvement Program Funds to Purchase the HSM?
  

Technical Assistance for HSM

• Where Can I Find Information on HSM Training?
• Are there available trainings related to the application of CMFs?
• Can I Download the FHWA Webinar Recordings?
• Where can I get help with the Manual?
• Where Can I Find Other HSM Users?
• Where can I find HSM Sample Problems?
• Where can I find HSM Case Studies?
• How can I justify the need of the HSM to management?
• How can data gained from implementation of the HSM be a benefit to other areas of the department?
  

Future Edition Highway Safety Manual

• Where do I find /send potential errata?
• How do I suggest additions to the HSM?
• When will the next edition of the Manual be published?
  

Predictive Method (Part C)

Background

• What are the limitations of current HSM Part C crash predictive models?
• Where can I find information on safety analysis for specific conditions such as animal crashes, Pedestrians and Bicycles, Parking, One-way Streets, and At-grade Rail Crossing?
• What is the difference between safety performance functions (SPFs) for network screening versus SPFs for prediction?
  

Data Requirements and Preparation

• Is there a minimum length criteria for segments to be used in HSM Part C analyses?
• Are there advantages to having segments of a minimum length when using part c methods?
• Is using estimated AADT values acceptable when applying HSM Part C Models?
• For the Part C Predictive Methods, is there a minimum AADT that is needed to make HSM analysis valid?
• Under what conditions is it appropriate to apply the EB procedure?
• If the EB procedure is applicable for only some sites (homogeneous segments or intersections) within a project, is it appropriate to apply the EB to those sites and not others – or should EB only be used if it can be applied to all sites in a project?
• Is it appropriate to compare results for alternative designs using EB to alternatives not using EB?
• What is the difference between observed, predicted, and expected average crash frequency?
• Is it appropriate to use CMFs from outside HSM Part C with the Part C models?
• How should I best determine whether a roadway segment or intersection is rural or urban?
• What if my site is not exactly like a site in the HSM?

Predictive Method for Rural Two-lane, Two-way Roads (Chapter 10)

• Does Chapter 10 - Predictive Method for Rural Two-Lane, Two-Way Roads apply to unpaved roads?
• Where can I get additional information about how to calculate the roadside hazard rating?
  

Specialized Procedures Common to All Part C Chapters (Appendix A)

• How should default values in the HSM be handled?
• Should separate calibration factors be developed for each crash type and severity level?
• Should separate calibration factors be developed for different AADT ranges?
• Should calibration factors be developed for portions of a highway network?
• How often should calibration factors be updated?
• What if I do not have a local calibration factor for the HSM Part C SPFs? What is the effect on the result?
• Can calibration factors from SafetyAnalyst be used in HSM calculations?
• How large should a site sample size be for calibration?
• What should be done in the case of insufficient data for a certain facility type? can a valid calibration factor still be determined?
• Is it important to replace the HSM default crash severity and collision type distribution tables by jurisdiction-specific data?
• Can data assembled for the development of calibration factors be used for a recalibration effort? 
• Can data assembled for the development of calibration factors be used for development of jurisdiction-specific SFPs?
• How should an agency prioritize data collection efforts when undertaking the calibration of several Part C predictive models?
• When should an agency develop jurisdiction-specific SPFs?
• How much is gained in accuracy by using an agency-developed SPF rather than a calibrated SPF?
• How should the usefulness of agency-developed SPFs be assessed to determine whether they are preferable to calibrated SPFs?
• What data quality is needed for agency datasets used to develop SPFs?
• If a highway agency develops agency-specific SPFs with its own data, and the agency-developed SPFs have a different shape from those found in HSM Part C, is there something wrong? Which SPF should be used?
• Why do the shapes of SPF curves for a given facility type often vary markedly from one agency to another or from one region to another within a state? Are such variations real or are they artifacts of sample size or data quality issues?
  

Predictive Method for Freeways (Chapter 18)

• How can I assess the safety tradeoffs between median barrier and flush median without sufficient clear zone?
• How was ramp metering considered in the development of the freeway crash prediction models?
• Does the freeway crash predictive method apply beyond the last interchange when a freeway transitions into a grade separated facility, and if so where does it end?
• Why does lighting not have any CMF in freeway and ramp models? Is the effect insignificant or has there not been data to support model development for this?
• Should the same criteria that are used to break the freeway segments into homogenous segments also be used to break speed‐change lanes to shorter speed‐change segments?
• It appears from the examples that the CMF for weaving decreases with increasing traffic volumes. This seems counter intuitive.
  

Predictive Method for Ramps (Chapter 19)

• Can the Predictive Method be applied to ramps providing two-way travel?
• What is the difference between a connector ramp and entrance or exit ramp at service interchange?
• For ramp terminals, the CMF for a channelization of a right turn lane is greater than 1.0. Why is this the case?
  

HSM-Related Tools

• What HSM-related tools are available?

AASHTOWare Safety Analyst

• What is Safety Analyst?
• How is SafetyAnalyst related to the HSM?
• How can my agency obtain the Safety Analyst software?
• Why don’t the HSM Part C and Safety Analyst require the same input information?
• Why don’t HSM Part C and Safety Analyst give similar results?
• Can calibration factors from Safety Analyst be used in HSM calculations?

Interactive Highway Safety Design Model (IHSDM)

• What is IHSDM?
• How is IHSDM related to the HSM?
• How can my agency obtain the IHSDM software?
• Is IHSDM Technical Support available?
• My agency wants to calibrate HSM Part C Predictive Models. How can IHSDM assist this effort?
• If an agency has developed their own SPFs, can they be entered into IHSDM?
• Can default crash severity and crash type distribution values be updated with agency-specific values in IHSDM?

HSM Spreadsheets

• Where can I find the latest version of the HSM spreadsheet tools? 
• Which HSM Part C methods do the HSM spreadsheets (i.e., those produced under NCHRP Project 17-38 and State agency enhanced versions) implement?
• What is ISATe and which HSM Part C methods do ISATe implement?

CMF Clearinghouse

• What is the CMF Clearinghouse?
• What is the purpose of the CMF Clearinghouse?
• How does the CMF Clearinghouse relate to the HSM?
• What is the difference between CMFs in the HSM and CMFs in the CMF Clearinghouse?
• What does the star quality rating mean?
• How is the star quality rating in the CMF Clearinghouse different from the notations (bold, italics, etc.) in the Highway Safety Manual?
• How do I choose between CMFs in my search results that have the same star rating but different CMF values?
• The CMF Clearinghouse presents both Crash Modification Factors and Crash Reduction Factors. What's the difference?
• How do the Clearinghouse crash severity terms Fatal, Serious Injury, and Minor Injury relate to the KABCO injury scale?
• How are states using the CMF Clearinghouse?
  

PLANSAFE

• Does PLANSAFE Implement the Highway Safety Manual?