Putting Together a Safety Program Kevin J. Haas, P.E.—Traffic Investigations Engineer Oregon Department of Transportation Traffic—Roadway Section (Salem,

Putting Together a Safety Putting Together a Safety ProgramProgram

Kevin J. Haas, P.E.—Traffic Investigations EngineerOregon Department of TransportationTraffic—Roadway Section (Salem, OR)

Presented at Roadway Safety for Local Agencies Workshop

February 19, 2010 (Corvallis, OR)

Putting Together a Safety Program—Kevin Haas, P.E.—ODOT Traffic-Roadway SectionFebruary 19, 2010 2

OverviewOverview

• Good safety program guidance is hard to find• AASHTO Highway Safety Manual• Relationship between crashes & exposure• Safety Performance Functions• Understanding & applying the HSM• Safety data gathering tools• Closing/Q & A

– Where can you find help in developing your local agency’s safety program?


A history lesson…A history lesson…• Good guidance publications for developing road

safety programs are hard to find– FHWA Manual on Uniform Traffic Control Devices

(MUTCD)– AASHTO A Policy on Geometric Design of Highways and

Streets (The “Green Book”)– TRB Highway Capacity Manual (HCM)


TRB identifies need for safety TRB identifies need for safety manualmanual• 1999

– TRB concerned about lack of highway safety information in the Highway Capacity Manual (HCM)

• 2003– TRB Task Force formed to

develop stand alone safety manual

• 2010– 1st Edition of the AASHTO

Highway Safety Manual (HSM) scheduled to be released

SAFETY


What is the HSM?What is the HSM?


What does this mean for my local agency?What does this mean for my local agency?

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

*Ezra Hauer, ITE Traffic Safety Toolbox Introduction, 1999


How can the HSM help me develop a How can the HSM help me develop a safety program for my local agency?safety program for my local agency?

Can you answer this question?

Is this road “safe” or “unsafe”?

What about this road?


Sample SPF for 2-Lane Rural Highways

0

5

10

0 1000 2000 3000 4000 5000

AADT

Cra

shes

per

m

ile

per

year

MountainousRollingLevel

• The relationship is typically not linear!• HSM uses regression equations called Safety Performance

Functions (SPF) to explain this relationship• SPFs can predict the average number of crashes per year for

an intersection or highway segment as a function of traffic volume

Understanding the relationship between Understanding the relationship between crashes & exposurecrashes & exposure


How would I develop a SPF for my local How would I develop a SPF for my local road system?road system?

• Plot crashes over a number of years on roads with similar characteristics

• Variability (randomness) of crashes handled by grouping crashes with similar volumes


How can SPFs help me build a safety How can SPFs help me build a safety policy or program for my local agency?policy or program for my local agency?

02468

1012

0 500 1000 1500 2000 2500 3000 3500 4000 4500

AADT

Cra

shes p

er

mil

e

per

year

Sample SPF for all 2-Lane Rural County Roads in Oregon

Data point representing existing

conditions for upcoming project

Potential local agency policy requires safety improvements to bring location back in line with or below SPF curve

Expected improvement from application of Crash Modification

Factors (CMF)


Why should I use the HSM as the basis for Why should I use the HSM as the basis for my local agency safety program?my local agency safety program?

11

22

33

The HSM does not

establish a legal standard

of care nor does it create a duty to the

public.


The HSM is The HSM is notnot a replacement for… a replacement for…

• Manual on Uniform Traffic Control Devices (MUTCD)• Your agency’s Policy or Traffic Manual • AASHTO “Green Book” (A Policy on Geometric

Design of Highways and Streets)


The HSM represents a new way of The HSM represents a new way of thinking…thinking…

Old (Reactive)

Descriptive analyses

Historical summary of crash

occurrence, type and/or severity at

a site

New (Proactive)

Quantitative predictive analyses

Future expected number of crashes based on the

geometric and operational

characteristics at a site


What do I need to start using the HSM to What do I need to start using the HSM to build my safety program?build my safety program?• Crash data

– Crash location– Date/time– Crash severity– Collision type– Basic roadway & vehicle

information• Facility data

– Roadway classification– Number of lanes & width– Shoulder presence & width– Intersection data (i.e. road

names, area type, traffic control, lane configurations)

• Traffic volume data– Annual Average Daily Traffic

(AADT) – Intersections Total Entering

Vehicles (TEV)


What are some examples of easily What are some examples of easily accessible tools to help collect accessible tools to help collect somesome of my of my safety data?safety data?

Video Logs

Roadside Inventories

Google Earth/Maps

Raw crash data & crash

reports

http://en.wikipedia.org/wiki/File:GoogleEarth-Ubuntu_Linux.png


The HSM is huge! How can I possibly The HSM is huge! How can I possibly understand all of it?understand all of it?

• Take baby steps!• Focus on parts of the

HSM that are easily implemented like CMFs


Crash Modification Factors (CMF)Crash Modification Factors (CMF)

• Quantify the expected change in crashes at a site caused by implementing a particular treatment– Also known by other terms such as

countermeasures or Crash Reduction Factors (CRF)

• Comparison usually involves evaluating safety conditions with or without a particular treatment, or safety conditions with one treatment versus another treatment


Application of CMFsApplication of CMFs

• Estimate the expected safety performance with the treatment in place

• Some typical examples of CMFs include:– Illuminating an unlighted road segment– Paving gravel shoulders– Signalizing a stop-controlled intersection– Deciding to use a 240-foot radius for a horizontal curve

instead of a 180-foot radius– Choosing a signal cycle time of 70 seconds instead of 80

seconds


Reliability of CMFsReliability of CMFs

• CMFs must be applied according to the conditions associated with each CMF (i.e. road type, traffic volume, crash severity, etc.)

• Some CMFs include a standard error which indicate variability in achieving expected results


How is ODOT using the latest tools & How is ODOT using the latest tools & methods in the HSM to transform our methods in the HSM to transform our safety program?safety program?• Predictive analysis

methods require data, data, & more data!

• ODOT is working on enhancing our data through our Asset Management Program

• Major data deficiencies in roadside character & cross-street intersection data


Where can I get help in developing my Where can I get help in developing my local agency’s safety program?local agency’s safety program?

• Contact OTREC or the Kiewit Center at OSU

• Refer to the HSM when it is published in 2010 by AASHTO

highwaysafetymanual.org

http://www.highwaysafetymanual.org/

http://otrec.us/

http://kiewit.oregonstate.edu/

http://oregonstate.edu/

Documents

Putting Together a Safety Program Kevin J. Haas, P.E.—Traffic Investigations Engineer Oregon Department of Transportation Traffic—Roadway Section (Salem,