THE HIGHWAY SAFETY MANUAL

1
THE HIGHWAY SAFETYMANUAL

• Jerry Pigman
• KY Transportation Center
• August 19, 2008
• KYTC Partnering Conference

2
Overview of Presentation

• What is the need for a Highway Safety Manual?
• What is the HSM?
• History on the Evolution of the HSM
• Organization and contents of the HSM

2
3
Is this road safe or unsafe?
3
4
What about these alternatives?Is one safer
that the others?
4
5
What is the Highway SafetyManual (or HSM)?

• Purpose To provide information and tools to
  assist transportation professionals in making
  decisions that have a positive impact on highway
  safety
• The HSM will focus on objective and quantitative
  measures of safety with a primary emphasis on
  crash frequency and severity
• The HSM will explicitly acknowledge gaps in
  knowledge regarding highway safety
• Gaps in knowledge will be addressed through
  continuing research and updating of the HSM

5
6
Targeted Users of the HSM

• Primary users likely to be front-line decisions
  makers
• Analysts studying the effect of actions on road
  users
• Planners, designers, and those responsible for
  operations and maintenance
• Secondary users
• Management
• Educational institutions
• Target audience may include professionals in the
  areas of
• Safety analysis ? Policymaking
• Programming ? Construction
• Project development ? Maintenance
• Planning ? Traffic Operations

6
7
The vision of the HSM adocument akin to the
HCM

• Represents quantitative state-of-art
  information
• Widely accepted within the professional practice
  of transportation engineering
• Science-based updated regularly to reflect
  research
• NOT a policy, standard, or legal document
• May be used in conjunction with other guidance
  documents

7
8
History
8
9
Research Development

• Relevant NCHRP projects
• 17-25 CRFs for Traffic Engineering ITS
  Improvements 12/07
• 17-26 Part III Urban Suburban Arterials 10/07
• 17-27 Parts I II (Intro Knowledge) 6/07
• 17-29 Part III Multi-lane Rural Highways 1/08
• 17-34 Parts IV V (Safety Systems Evaluation)
  12/06
• 17-36 Production of the First Edition ?/09
• Other related initiatives
• IHSDM, Safety Analyst, Human Factors Guidelines

9
10
Key Players in the Development of the HSM First
Edition

• NCHRP Panel
• TRB HSM Task Force
• Provides direction and oversight of research and
  HSM content
• AASHTO HSM Joint Task Force
• Provides the representative perspective of a
  significant group of future HSM users
• Provide a bridge between the other AASHTO
  committees and TRB HSM Task Force
• HSM Production Contract Team
• Implement the actions resulting from the
  direction and oversight from NCHRP Panel, TRB
  Task Force, and AASHTO Joint Task Force

10
11
A New Era inHighway Safety Analysis

• Modeling (SPFs) in First Edition HSM will be
  rudimentary
• Gaps in knowledge (AMFs)
• Encourage
• Evidence-based decision making
• More resources focused on safety research
• Innovative approaches to improving safety

11
12
Outline of HSM First Edition

• Part A Introduction and Fundamentals
• Part B Safety Process
• Part C Predictive Methods
• Part D Accident Modification Factors
• Glossary

12
13
Part A Introduction andFundamentals

• Chapter 1 Introduction and Overview
• Chapter 2 Human Factors in Road Safety
• Chapter 3 Fundamentals

13
14
Part B Safety Process

• Chapter 4 Network Screening
• Chapter 5 Diagnosis
• Chapter 6 Selection of Countermeasures
• Chapter 7 Economic Appraisal
• Chapter 8 Prioritization of Improvement projects
• Chapter 9 Safety Effectiveness Evaluation

14
15
Part C Predictive Methods

• Chapter 10 Rural, Two-Lane Roads
• Chapter 11 Rural, Multilane Highways
• Chapter 12 Urban/Suburban Arterial Highways

15
16
Example Safety Performance Function

• Four-Lane Divided Road Total Accidents Per Year

16
17
General Form of PredictionMethodology

• where
• N predicted number of accidents per year for
  roadway segment or intersection
• Nbase predicted number of accidents per year
  for
• nominal or base conditions
• C calibration factor to convert predicted
  accident frequency to local conditions
• AMFn accident modification factor to convert
  nominal or base conditions to actual site
  conditions

17
18
Part D Predictive Methods

• Chapter 13 Roadway Segments
• Chapter 14 Intersections
• Chapter 15 Interchanges
• Chapter 16 Special Facilities Geometric
• Situations
• Chapter 17 Road Networks

18
19
Sample AMFs CurrentlyIncluded in Draft HSM
AMFs for Roadway Segment Design Elements

• Cross-Section Elements
• Modify lane width
• Add lanes
• Road diets
• Provide median
• Modify shoulder width
• Improve shoulder type

19
20
Sample AMFs CurrentlyIncluded in Draft HSM
AMFs for Roadway Segment Design Elements

• Roadside Elements
• Flatten sideslopes
• Increase distance to roadside features
• Change roadside barrier
• Install median barrier
• Install crash cushions
• Reduce Roadside Hazard Rating

20
21
Sample AMFs CurrentlyIncluded in Draft HSM
AMFs for Roadway Segment Design Elements

• Alignment Elements
• Modify horizontal curve radius and length
• Correct superelevation deficiency
• Change vertical grade

30
22
HSM PART CMETHODOLOGIESDATA NEEDS

• 3 Types of data needed
• Site characteristics
• Traffic volumes
• Crashes

23
23
SITE CHARACTERISTICS

• Roadway segments
• Area type
• Site length
• Roadway cross section
• Added lanes
• Horizontal and vertical alignment
• Driveways
• Roadside conditions
• Lighting

24
24
SITE CHARACTERISTICS

• Intersections
• Configuration
• Type of traffic control
• Enforcement devices
• Turn lanes
• Intersection angle
• Sight distance
• Terrain
• Lighting

25
25
TRAFFIC VOLUME DATA

• Annual Average Daily Traffic

26
26
CRASH DATA

• History of crashes
• Observed crash data
• Predicted crashes from HSM methodology
• Combine using Empirical Bayes method

27
27
APPLICATIONS OF HSMDATA NEEDS

• Dividing sections or projects into homogeneous
  segments and intersections
• Calibrating models
• Applying models to specific road segments and
  intersections
• Performing Empirical Bayes weighing with crash
  data

28
28
UPCOMING ACTIVITIESRELATED TO HSM

• HSM Task Force (TRB an AASHTO) mid-year meeting
  August 19-22
• Second complete draft of HSM will be reviewed
• Third draft will be completed and reviewed for
  TRB Annual Meeting
• Submitted as final NCHRP report
• Sent to AASHTO for ballot and publication

29
29
Upcoming Activities

• Finalize rural multilane highway research
• Finalize pedestrian safety research
• First draft HSM late Spring/early Summer 2008
• Review and provide comments
• Final draft for consideration of HSM Task Force
  NCHRP Panel, and AASHTO Task Force January 2009
• Publish NCHRP reports in mid-2009
• Possible publishing by AASHTO in 2010/2011?

22
30
FINAL IMPLEMENTATION STEP
NCHRP project to develop briefing and training
materials for HSM

• Oregon State University and subcontractors
• High and mid-level DOT training modules
• More detailed training for actual HSM users

21
31
HIGHWAY SAFETYMANUAL
Websites of interest www.highwaysafetymanual.org
www.trb.org/onlinepubs/nchrp_rrd_329.pdf
31
32
Thank YouAny Questions?
jpigman_at_engr.uky.edu 859-257-4521
32