OVERVIEW OF THE NEW HIGHWAY SAFETY MANUAL

Ray Krammes, FHWA

Missouri Traffic & Safety ConferenceMay 12, 2009 Columbia, Missouri

Presentation Summary

• What is the HSM?• Why is the HSM needed?• What is covered by the HSM?• Who should use the HSM?• When will the HSM be available?• What support will be available to implement

the HSM?• Where can one find more about the HSM?

WHAT IS THE HSM?Overview of the new HSM

WHAT IS THE HSM?

THE VISION OF THE HSM - A DOCUMENT AKIN TO THE HCM

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WHAT THE HSM IS NOT

• The HSM does not set requirements or mandates• The HSM is not a best practice document for design or

operations.• The HSM contains no warrants or standards

and does not supersede other publications that do.

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WHY IS THE HSM NEEDED?Overview of the new HSM

IS THIS ROAD “SAFE” OR “UNSAFE”?

What does safety really mean?

Examined in reference to compliance with standards, warrants, guidelines and sanctioned design procedures

The expected or actual crash frequency and

severity for a highway or roadway

HIGHWAY SAFETY HAS TWO DIMENSIONS

*Ezra Hauer, ITE Traffic Safety Toolbox Introduction, 1999

SUBSTANTIVE SAFETY MAY VARY WHEN NOMINAL SAFETY DOES NOT

Existing ConditionsExisting Conditions Alternative 1Alternative 1

Alternative 2Alternative 2 Alternative 3Alternative 3

Substantive Safety

• Best measured in terms of expected (long-term) average crash frequency

• Ways to estimate:– Crash data– Predictive methods

• Safety Performance Functions (SPFs)• Accident Modification Factors/Functions (AMFs)

– Combination (Empirical Bayes)

1983-1985 Accidents

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1986-1988 Accidents

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1989-1991 Accidents

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1983-1995 Accidents

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WHAT IS COVERED BY THE HSM?Overview of the new HSM

OUTLINE OF THE HSM

PART AINTRODUCTION, HUMAN FACTORS, &

FUNDAMENTALS

Npredicted = Nspfx*(AMF1x*AMF2x*... *AMFyx )*Cx

Where,Npredicted = predicted average crash frequency for a

specific year for site type x;Nspf x = predicted average crash frequency determined

for base conditions of the SPF developed for site type x;

AMFyx = Accident Modification Factors specific to SPF for site type x;

Cx = calibration factor to adjust SPF for local conditions for site type x.

PART BROADWAY SAFETY MANAGEMENT PROCESS

4 6 7 8 9

Chapter 4. Network Screening

PART CPREDICTIVE METHODS

Special Part C Special Part C Common ProceduresCommon Procedures

• Calibration• Combining predicted

with observed crashes

Exhibit 10-5: Graphical Form of SPF for Rural Two-Lane Two-Way Roadway Segments(Equation 10-6)

Exhibit 10-9: Graphical Representation of the SPF for Four-leg STOP controlled (4ST) Intersections(Equation 10-9)

PART DACCIDENT MODIFICATION FACTORS

Exhibit 10-16: AMF for Shoulder Width on Roadway Segments (AMFwra)

WHO SHOULD USE THE HSM? Overview of the new HSM

WHO SHOULD USE THE HSM?

WHEN WILL THE HSM BE AVAILABLE?

Overview of the new HSM

IMPLEMENTATION SCHEDULE

WHAT SUPPORT WILL BE AVAILABLE TO IMPLEMENT THE HSM?

Overview of the new HSM

TRAINING & OUTREACH ACTIVITIES

• Sept – Nov 2009– Conduct two or three multi-state pilot courses

• TRB 2010 Annual Meeting– One-day workshop

• Training materials, including “Train-the-trainer” available upon HSM release

FHWA Tools Supporting HSM Use

HSM Part Supporting Tool

PART B: Roadway Safety Management Process

SafetyAnalystwww.safetyanalyst.org

PART C: Predictive Methods

IHSDMwww.ihsdm.org

PART D: Accident Modification Factors

CRF/AMF Clearinghouse

WHERE CAN ONE FIND MORE ABOUT THE HSM?

Overview of the new HSM

http://www.highwaysafetymanual.org

THE END

Questions?