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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
11
22
33
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.
vs
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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1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5
Mile Point
Num
ber
of A
ccid
ents
1986-1988 Accidents
0
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1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5
Mile Point
Num
ber
of A
ccid
ents
1989-1991 Accidents
0
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1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5
Mile Point
Num
ber
of A
ccid
ents
1992-1994 Accidents
0
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1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5
Mile Point
Num
ber
of A
ccid
ents
1983-1995 Accidents
0
2
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1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5
Mile Point
Num
ber
of A
ccid
ents
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?
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