1. Highway Safety Manual (HSM) into Safety Processing
How to Incorporate the
Highway Safety Manual (HSM)
into Safety Processing
Presented by
Gerald Dildine,
ITIS Corporation
Project Review Header Slide
Includes:
Project Title
Date of Project Review
Presented To Name/Title
Presented By Name/Title

2. Design HSM Processing Questions:
How many of you currently do processing for HSM statewide?
Why consider it?
What does it offer Safety Records Managers?
What are the benefits?
What should be the role?

3. HIGHWAY SAFETY MANUEL
Purpose of HSM processing is to provide “Predictive Crash Data”, based upon following the guidelines of the Highway Safety Manual.
Within the processing of HSM, three types of predictive crashes are discussed. SPF, Predictive, and Expected

4. HSM CORE BENEFITS
Core benefits of Predictive Crashes are to improve over the weaknesses related to using Crash History:
Removes problems with “Regression to the mean” associated with using crash history.
Provides values even when sparse crash data exists.
Provides much more consistent “fabric” of data.

5. A MORE CONSISTENT DATA APPROACH
Removes Misleading Spikes
Removes & Fills in Gaps
History - Blue
HSM - Black

6. HSM ANCILLARY BENEFITS
A number of ancillary benefits come through artifacts from processing

7. BASIC STEPS IN HSM PROCESSING
CRASH HISTORY
ROADWAY
SPF
PREDICTIVE
EXPECTED
Integrate roadway and crash elements statewide
Process SPFs with variations for each facility and severity
Factor CMFs and calibrate SPFs
Combine model with history

8. HSM PROCESSING 13 FACILITY TYPES CRASH HISTORY SPF PREDICTIVE EXPECTED
ROADWAY
20 SPFs
24 CMFs
When processing, HSM forces us to organize our data better, and produces calculations which are reusable downstream
18 ROADWAY DATA ELEMENTS

9. Roadway Characteristics
HSM PRODUCTS
HSM PROCESSING
Predicted Crashes
Facility Types
CMFs/ Risks
Safety Indexes
Rankings
Hot Spots
Products / Byproducts
Downstream Products
Assembly and calculations result in very useful byproducts,
Downstream calculations make use of HSM processing
Roadway Characteristics

10. HSM ANCILLARY BENEFITS
Ancillary benefits of HSM processing include the following:
Organization and consolidation of required supporting roadway characteristics.
Organization of roadways into facility types, which enables better comparative analysis.
Exposure of the most significant risks associated with each roadway section.
Improvements to downstream processing of scoring indexes and rankings.

11. ROADWAY CHARACTERISTICS
Facility type
Lane width
Shoulder width and type
Horizontal curve (radius and length)
Superelevation
Vertical grade
Lighting
Approach density
Speed limit
Center-line rumble strip
Passing lanes
TWLTL
Roadside hazard rating

12. FACILITY TYPES RuFl2 Rural, Flat, 2 lane RuFl2+ Rural, Flat, 2+ lane
RuFlIB Rural, Flat, Interstate (both directions)
RuFlID Rural, Flat, Interstate (Dec direction)
RuFlII Rural, Flat, Interstate (Inc direction)
RuMt2 Rural, Mountainous, 2 lane
RuMt2+ Rural, Mountainous, 2+ lane
RuMtIB Rural, Mountainous, Interstate (both directions)
RuMtID Rural, Mountainous, Interstate (Dec direction)
RuMtII Rural, Mountainous, Interstate (Inc direction)
RuRo2 Rural, Rolling, 2-lane
RuRo2+ Rural, Rolling, 2+ lane
RuRoIB Rural, Rolling, Interstate (both directions)
RuRoID Rural, Rolling, Interstate (Dec direction)
RuRoII Rural, Rolling, Interstate (Inc direction)
Ur Urban
UrIB Urban Interstate (both directions)
UrID Urban Interstate (Dec direction)
UrII Urban Interstate (Inc direction)

13. CMFs/RISKS Lane width Shoulder width and type
Horizontal curve (radius and length)
Superelevation
Vertical grade
Approach density
Center-line rumble strip
Passing lanes
TWLTL
Roadside hazard rating
Others

14. EXPECTED CRASHES
Expected crashes are the primary result from HSM processing, but the work doesn’t end there!
Performing HSM processing across a highway network can be used to develop a more consistent reliable database for crash numbers.
Expected crashes can be used for scoring and ranking of segments.
Cmfs can be used for risk calculations
Expected crashes can be used for benefits calculations

15. SAMPLE DOWNSTREAM FUNCTIONS
SAFETY SCORING
SAFETY BENEFIT
RISK DETAILS

16. SAMPLE PRODUCTS: CRASH PROFILE
RANKING
EXPECTED
CRASHES
CRASHES LAST 5
YEARS (BY
SEVERITY)
PMPY

17. SAMPLE PRODUCTS: ROADWAY PROFILE
POSTED SPEED
LIMIT
TERRAIN
URBAN RURAL
ACCESS
LOCATIONS
AND DENSITY
SHOULDER
WIDTH
TOP PAVED

18. SAMPLE PRODUCTS: NUMBER OF LANES LANE CONFIGURATION TRAFFIC VOLUME
TRUCK
PERCENT
TRAFFIC
VOLUME
CURVE
ADVISORY
ROADSIDE
HAZARD
RATING (1-7)

19. SAMPLE PRODUCTS:
FRICTION
PAVEMENT
RATING
RUTTING

20. BENEFITS Project decision-making Hot spot creation Systemic analysis
Studies
Overall benefits come in the form of providing better consistent information which avoids some of the pitfalls of crash history
Better results from network screening and/or hot spot development
A more constent fabric of for statewide systemic analysis and specific studes

21. WHERE DO WE GO FROM HERE?
HSM is deployed into the Department’s Safety Management System (Economic Analysis)
Still more work to do in finalizing Intersections.
Possible work in Interchanges and perhaps roundabouts.
Still completing full inclusion in to analytics processing.

22. A SPECIAL THANK YOU TO:
Wyoming DOT, for the opportunity to work on HSM.
Joe McCarthy, for use of some slide information.