hwy safety manual 05-08-09

7/30/2019 Hwy Safety Manual 05-08-09

1/29

Over v i ew o f t h e Ov er v i ew o f t h e

AASH TO H i g h w a y Sa fet y M a n u a l A ASH TO H i g h w a y Sa fet y M a n u a l

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

Presented at the ACEC/ODOT Liaison Committee MeetingMay 8, 2009


2/29

Overview of AASHTO HSMKevin Haas, P.E.ODOT Traffic-Roadway SectionMay 8, 2009 2

Over v i ew o f Pr esen t a t i o n Over v i ew o f Pr esen t a t i o n

What is the Highway Safety Manual?

HSM purpose

Transportation Research Board (TRB) &

American Association of Transportation andState Highway Officials (AASHTO)involvement in development of the HSM

HSM content & methodologies

HSM 1st Edition release schedule & training

opportunities


3/29


4/29Overview of AASHTO HSMKevin Haas, P.E.ODOT Traffic-Roadway SectionMay 8, 2009 4

W h a t a b o u t t h ese a l t er n a t i v es? W h a t a b o u t t h ese a l t er n a t i v es? I s o n e I s o n e safersa fert h a n t h e o t h er s? t h a n t h e o t h er s?


5/29Overview of AASHTO HSMKevin Haas, P.E.ODOT Traffic-Roadway SectionMay 8, 2009 5

W ha t i s t h e H i g h w a y Sa fet y M a n u a l ? W h a t i s t h e H i g h w a y Sa fet y M a n u a l ?

Purpose

Provide analytical tools and techniques forquantifying the safety effects of decisionsmade in planning, design, operations, andmaintenance

Objective

Reduce the number and severity of crasheswithin the limits of available resources, science,technology, and legislatively mandated priorities


6/29


W h o i s t h e i n t en d ed a u d i en ce o f t h e W h o i s t h e i n t en d ed a u d i en ce o f t h e H S M ? H S M ?

Employees or consultants working for transportation

agencies at the state, county, metropolitan planningorganization (MPO), or local level


7/29


W h a t a r e t h e q u a l i f i ca t i o n s n eed ed t o W h a t a r e t h e q u a l i f i ca t i o n s n eed ed t o u se t h e H SM ?u se t h e H SM ?

Users should have an understanding of thetransportation safety field throughexperience, education or both

Familiar with the general principles and practiceoftransportation safety;

Familiar with basic statistical procedures and

interpretation of results; and Suitable competence to exercise sound

engineering judgment and reasoning.


8/29


Th e H SMTh e H SMv i s i o nv i s i o na d o cu m en t a s a d o cu m en t a s w i d el y a ccep t ed a s t h e H CMw i d el y a ccep t ed a s t h e H CM

Definitive

Represents quantitativestate-of-the-artinformation

Widely accepted By engineers & other

transportationprofessionals

Science-based

Regularly updated toreflect latest research

SAFETY


9/29


Th e H SM i s Th e H SM i s n o tn o ta r ep l a cem en t f o r a r ep l a cem en t f o r

Manual on Uniform Traffic Control Devices (MUTCD)

AASHTO Green Book (A Policy on GeometricDesign of Highways and Streets)


10/29


H SM H i st o r y H SM H i st o r y

First discussed 10 years

ago within theTransportationResearch Board (TRB)

concerning lack ofhighway safetyinformation in the

Highway CapacityManual (HCM)


11/29


H SM fou n d a t i o n l a i d i n 19 99 H SM fou n d a t i o n l a i d i n 19 99

Breakout session at TRB Annual Meeting inJanuary concluded:

The absence of, and the need for a singleauthoritative document to use for estimatingsafety impacts

TRB workshop in December confirmed:

The crucial need for a stand-alone document tobe named the Highway Safety Manual


12/29


W h a t h a s been h ap pen i n g si n ce 1999 ?W h a t h a s been h ap p en i n g si n ce 1999 ?

TRB Joint Subcommittee for theDevelopment of a Highway Safety Manualcreated in May 2000 with support from:

American Association of State Highway andTransportation Officials (AASHTO)

Federal Highway Administration (FHWA)

Institute of Transportation Engineers (ITE)


13/29


TRB H SM Ta sk Fo r ce ( AN B25T ) TRB H SM Ta sk Fo r ce ( AN B25T )

The HSM Task Force evolved from the TRBJoint Subcommittee and was formed in June2003

Over 100 Task Force members have beenworking on the HSM since 2003

Key objective

Provide direction and oversight of researchleading to development of the HSM


14/29


K ey r esea r ch & devel o pm en t ef f o r t s K ey r esea r ch & devel o pm en t ef f o r t s

National Cooperative Highway ResearchProgram (NCHRP)

Crash Reduction Factors (CRF) for TrafficEngineering & ITS Improvements

Safety Systems & Evaluation

Production of the HSM 1st Edition

Other related initiatives Interactive Highway Safety Design Model

(IHSDM)

SafetyAnalyst


15/29


A n ew w a y o f t h i n k i n g A n ew w a y o f t h i n k i n g

Old

Descriptiveanalyses

Historical summaryof crash

occurrence, typeand/or severity

at a site

New

Quantitative predictiveanalyses

Future expected number ofcrashes based on the

geometric andoperational

characteristics at a site


16/29


D escr i p t i v e an a l y ses D escr i p t i v e an a l y ses

Based on historical data

Crash frequency Crash rate

Equivalent property damage only (EPDO)

Example of descriptive analysis tool: Safety Priority Indexing System (SPIS)


17/29


Qu an t i t a t i v e p r ed i ct i v e a n a l y ses Qu an t i t a t i v e p r ed i ct i v e a n a l y ses

Predicted (expected) number of crashes

Geometric & operational characteristics Existing conditions

Future conditions/design alternatives

Example of quantitative predictive tool:

Safety Performance Functions (SPF)

Npredicted = NSPFx * (AMF1x * AMF2x * * AMFyx) * Cx

Where:

Npredicted = predictive model estimate of crash frequency for a specific year on site typex(crashes/year);

NSPFx = predicted average crash frequency determined for base conditions with theSafety Performance Function representing site typex(crashes/year);

AMFyx = Accident Modification Factors specific to site typex;

Cx = Calibration Factor to adjust for local conditions for site type


18/29


Sa f et y Per f o r m an ce Fu n ct i o n s (SPF ) Sa f et y Per f o r m an ce Fu n ct i o n s (SPF )

Regression equations

Predict the average number of crashes per year foran intersection or highway segment as a function oftraffic volume

Typically not a linear relationship!

Sample SPF for 2-Lane Rural Highways

0

5

10

0 5000 10000 15000 20000

AADT

Crashesper

mileperyea

Mountainous

Rolling

Level


19/29


Po t en t i a l SPF r el a t i o n sh i p t o DOT po l i cy Po t en t i a l SPF r el a t i o n sh i p t o D OT po l i cy

02468

10

1214

0 5000 10000 15000 20000

AADT

Crashespermil

peryear

SPF for all 2-LaneRural Mountainous

Highways in Oregon

Data pointrepresenting existing

conditions forupcoming STIP project

Potential DOT policy requires safetyimprovements to bring location back in

line with or below SPF curve

Expected improvementfrom application of

Accident ModificationFactors (AMF)


20/29


Acci d en t M od i f i ca t i o n Fa ct o r s ( AM F) A cci d en t M od i f i ca t i o n F a ct o r s ( AM F)

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)

Some examples of AMFs include: Installing a roundabout or traffic signal at a stop-controlled

intersection

Deciding to use a 240-foot radius for a horizontal curveinstead of a 180-foot radius

Installing centerline rumble strips on 2-lane rural highway


21/29


Rel i a b i l i t y o f R el i a b i l i t y o f A M F s AM F s

AMFs must be applied according to the conditions

associated with each AMF (i.e. road type, trafficvolume, crash severity, etc.)

Some AMFs include a standard error which indicate

variability in achieving expected resultsHSM Exhibit 14-7 Potential Crash Effects of Converting Signalized Intersections into Modern Roundabout

Treatment Setting (IntersectionType)

Traffic Volume Accident type(Severity)

AMF Std. Error

All types (All severities) 0.99* 0.1

All types (Injury) 0.40 0.1

Suburban (Two lanes) All types (All severities) 0.33 0.05

All types (All severities) 0.52 0.06

All types (Injury) 0.22 0.07

Base Condition: Signalized intersection NOTE: Bold text is used for the most reliable AMFs. These AMFs have a standard error of 0.1 or less.

*Observed variability suggests that this treatment could result in an increase, decrease or no change in crashes.

All settings (One or twolanes)

Urban (One or two

Lanes)

Convert signalized

intersection tomodern roundabout

Unspecified


22/29


Ou t l i n e o f H SMOu t l i n e o f H SM11ststEd i t i o n E d i t i o n

Part AIntroduction, Human Factors, and

Fundamentals

Part BRoadway Safety Management

Process Part CPredictive Methods

Part DAccident Modification Factors

Glossary


23/29


Pa r t APa r t AI n t r o d u c t i o n , H um a n Fa ct o r s, a n d I n t r o d u c t i o n , H um a n Fa ct o r s, a n d F u n d ame n t a l s F u n d ame n t a l s

Chapter 1Introduction and Overview

Chapter 2Human Factors

Chapter 3Fundamentals


24/29


Pa r t B Pa r t B

Roa dw a y Sa fet y M a n a g em en t R oa dw a y Sa fet y M a n a g em en t

Pr ocessPr ocess

Chapter 4Network Screening

Chapter 5Diagnosis

Chapter 6Select Countermeasures

Chapter 7Economic Appraisal Chapter 8Prioritize Projects

Chapter 9Safety Effectiveness Evaluation


25/29


Pa r t C Pa r t C Pr ed i ct i v e M et h o d s Pr ed i ct i v e M et h o d s

Chapter 10Rural, Two-Lane Roads

Chapter 11Rural, Multilane Highways

Chapter 12Urban and Suburban Arterial

Highways AppendixCalibrating Safety Performance

Functions


26/29


Pa r t D Pa r t D Acci d en t M od i f i ca t i o n Fa ct o r s A cci d en t M od i f i ca t i o n Fa ct o r s

Chapter 13Roadway Segments

Chapter 14Intersections

Chapter 15Interchanges

Chapter 16Special Facilities and GeometricSituations

Chapter 17Road Networks


27/29


Th e H SMTh e H SMa n ew er a i n h i g h w a y sa fet y ! a n ew er a i n h i g h w a y sa f et y !

The 1st Edition of the HSM is currently going through

the AASHTO balloting process Scheduled to be published in late 2009/early 2010

Modeling (SPFs) in 1st Edition will be rudimentary

Gaps in knowledge (AMFs will not be available forevery treatment in every conceivable roadenvironment)

The HSM will encourage: Evidence-based decision making

More resources focused on safety research

Innovative approaches to improving safety


28/29


U p com i n g H SM t r a i n i n g op p o r t u n i t i es U p com i n g H SM t r a i n i n g op p o r t u n i t i es

Traffic Day 2009

Monday, October 19Valley River Inn (Eugene)

HSM workshop for ODOT &consultant engineering staff

Oregon TransportationSafety Conference

Tuesday, October 27

Hood River

3-hour HSM workshop as partof opening day of conference


29/29


Cou n t d ow n t o t h e 1 Co u n t d ow n t o t h e 1 ststEd i t i o n o f t h e H SMEd i t i o n o f t h e H SM

For the latest information on the Highway Safety

Manual go to:

www.highwaysafetymanual.org
http://www.highwaysafetymanual.org/http://www.highwaysafetymanual.org/

hwy safety manual 05-08-09

Documents