THE HIGHWAY SAFETY MANUAL

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THE HIGHWAY SAFETY MANUAL
Michael S. Griffith Federal Highway
Administration July 26th, 2004
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Growing Recognition
Professionals do not have the needed tools to
explicitly consider safety when making decisions
related to highway facilities.
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What is the Highway Safety Manual (or HSM)?

• Purpose to provide the best factual information
  and tools in a useful form to facilitate roadway
  planning, design, operations, and maintenance
  decisions based on explicit consideration of
  their safety consequences

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Targeted Users

• Primarily, analysts studying the impact of
  actions on roadway users
• Planning, design and operations studies
• Secondary users
• Management
• Educational Institutions

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Research Development

• Relevant NCHRP efforts
• NCHRP 17-18(4) HSM scoping study and development
  of prototype chapter on rural two-lane highways
  Completed
• NCHRP Project 17-26 Development of Models for
  Prediction of Expected Safety Performance for
  Urban and Suburban Arterials Started March 2003
• NCHRP 17-27 Prepare Parts I and II of the
  Highway Safety Manual Started May 2004
• NCHRP 17-29 Safety Prediction Models for Rural
  Multilane Highways for Use in the Highway Safety
  Manual Started May 2004
• Other efforts SafetyAnalyst, IHSDM, and Human
  Factors Guide

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Resources

• Development of a Highway Safety Manual - Final
  Report, March 2004
• Development of a Highway Safety Manual Research
  Results Digest, March 2004, Number 286
• Website http//www.highwaysafetymanual.org/

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Outline for Initial Version of the HSM

• Part I Introduction and Fundamentals
• Part II Knowledge
• Part III Predictive Methods
• Part IV Safety Management of a Roadway
  System
• Part V Safety Evaluation
• Glossary

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Part I Introduction and Fundamentals
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Part I - Chapter 1Introduction and Overview

• 1.1. Purpose
• 1.2. Background on the Need for HSM
• 1.3. Scope of the HSM
• 1.4. Intended Audience
• 1.5. Intended Use of the HSM
• 1.6. Context for the HSM Use and Misuse of the
  Manual
• 1.7. Nature of the HSM
• 1.8. Organization of HSM

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Part I - Chapter 2Fundamentals

• 2.1. What is Safety?
• 2.2. How Road Safety is Measured?
• 2.3. Effect of Traffic Volume Vehicle Mix
• 2.4. Safety Performance Functions and Crash
  Modification Factors
• 2.5. Human Factors in Road Safety
• 2.6. Speed and Safety

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Part II - Knowledge
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Part II - Chapter 3Roadway Segments

• 3.1. Safety Effects of Highway Design Elements
• 3.2. Safety Effects of Traffic Control and
• Operational Elements
• 3.3. Pedestrian and Bicycle Safety on Roadway
  Segments
• 3.4. Safety Effects of Other Elements

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Part II - Chapter 4Intersections

• 4.1. Safety Effects of Intersection Design
  Elements
• 4.2. Safety Effects of Intersection Traffic
  Control and Other Operational Elements
• 4.3. Safety Effects of Other Intersection
  Related Features
• 4.4 Pedestrian and Bicycle Safety
  at Intersections

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Part II - Chapter 5Interchanges

• 5.1. Safety Effects of Interchange Design
  Elements
• 5.2. Safety Effects of Traffic Control and
  Operations Elements

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Part II - Chapter 6Special Facilities and
Geometric Situations

• 6.1. Railroad-Highway Grade Crossings
• 6.2. Construction and Maintenance Work Zone Areas

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Part II - Chapter 7Road Networks

• 7.1. Introduction
• 7.2. Safety in Transportation Network Planning
• 7.3. Safety in the Planning and Design of
  Residential Neighborhoods and Commercial Areas
• 7.4. One-Way Systems and Turn Restrictions
• 7.5. Safety in Traffic Calming
• 7.6. Access Management
• 7.7. Road-use Culture

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Part III Predictive Methods
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Part III - Chapter 8Rural, Two-Lane Roads

• 8.1. Introduction
• 8.2. Methodology
• 8.3. Applications
• 8.4. Example Problems
• 8.5. References
• Appendices

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Prototype Chapter 8 - Overview

• Scope Estimates the safety performance of a
  rural two-lane highway segments and at-grade
  intersections
• Applications
• Individual segments and intersections
• Overall project

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Prototype Chapter 8 - Overview

• Explicitly Considers
• Roadway Segments (ADT, lane shoulder width,
  shoulder type, horizontal curvature, grade,
  driveways, and roadside design)
• Intersections (type of control, number of
  approach lanes volume, sight distance, skew
  angle, and turn lanes)

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Part III - Chapter 9Rural, Multi-Lane Highways

• 9.1. Introduction
• 9.2. Methodology
• 9.3. Applications
• 9.4. Safety Issues Not Explicitly addressed by
  the Methodology
• 9.5. Example Problems
• 9.6. References

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Part III - Chapter 10Urban/Suburban Arterial
Highways

• 10.1. Introduction
• 10.2. Methodology
• 10.3. Application
• 10.4. Safety Issues Not Explicitly addressed by
  the Methodology
• 10.5. Example Problems
• 10.6. References

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Part IV Safety Management of a Roadway System

• Chapter 11. Identification of Sites with
  Promise
• Chapter 12. Diagnosis of the Nature of Safety
  Problems at Specific Sites
• Chapter 13. Selection of Countermeasures to
  Reduce Accident Frequency and Severity at
  Specific Sites
• Chapter 14. Economic Appraisal of all Sites
  under Consideration
• Chapter 15. Prioritized Rankings of
  Improvement Projects

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Part V Safety Evaluation
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Part V - Chapter 16Safety Evaluation of
Implemented Measures

• 16.1. Introduction
• 16.2. Why Evaluate?
• 16.3. Data Needs and Limitations
• 16.4. Approach to Conducting A Valid Evaluation

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When available?

• First edition expected to be released in 2007 or
  2008.

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Data Requirements for HSM

• Data Requirements Guide will be developed.

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Requirements
R Data is Required and there is no default
value (the process would be incomplete without
the user entering the data). RD Data is
Required and there is a Default Value if the user
does not enter the data. O Data is used by the
process if available but is Optional.
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Basic Data Needs

• Crash
• Roadway
• Traffic

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Prototype Chapter (Rural, Two-Lane Roads)
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Crash Data - Required

• Crash History Data
• Frequency and Severity Data by Location and by
  Year

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Traffic Data - Required
Average Daily Traffic by location
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Roadway Data Horizontal
Data Elements Tangent Simple Curve Spiral
Curve Deflection Heading Coordinate Station
Equation
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Roadway Data Vertical
Data Elements Vertical Point of
Intersection Elevation Tangent Curve
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Roadway Data Cross Section
Data Elements Pavement (Cross Slope) Shoulder
(Width and Type)
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Roadway Data Lane Group
Data Elements Thru Passing Turn Two-way
left-turn Climb
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Roadway Data Roadside Group
Data Elements Driveway Density Hazard Rating
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Intersection Data
Traffic Control Number of Legs Intersection Sight
Distance Number of approach lanes volume Turn
lanes Skew angle