1 THE HIGHWAY SAFETY MANUAL Michael S. Griffith Federal Highway Administration July 26 th, 2004

2 Growing Recognition … Professionals do not have the needed tools to explicitly consider safety when making decisions related to highway facilities.

3 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

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

5 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

6 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 –

7 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

8 Part I – Introduction and Fundamentals

9 Part I - Chapter 1 Introduction 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

10 Part I - Chapter 2 Fundamentals 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

11 Part II - Knowledge

12 Part II - Chapter 3 Roadway 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

13 Part II - Chapter 4 Intersections 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 4.4Pedestrian and Bicycle Safety at Intersections

14 Part II - Chapter 5 Interchanges 5.1.Safety Effects of Interchange Design Elements 5.2.Safety Effects of Traffic Control and Operations Elements

15 Part II - Chapter 6 Special Facilities and Geometric Situations 6.1.Railroad-Highway Grade Crossings 6.2.Construction and Maintenance Work Zone Areas

16 Part II - Chapter 7 Road 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

17 Part III – Predictive Methods

18 Part III - Chapter 8 Rural, Two-Lane Roads 8.1.Introduction 8.2.Methodology 8.3.Applications 8.4.Example Problems 8.5.References Appendices

19 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

20 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)

21 Part III - Chapter 9 Rural, 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

22 Part III - Chapter 10 Urban/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

23 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

24 Part V – Safety Evaluation

25 Part V - Chapter 16 Safety 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

26 When available? First edition expected to be released in 2007 or 2008.

27 Data Requirements for HSM Data Requirements Guide will be developed.

28 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.

29 Basic Data Needs Crash Roadway Traffic

30 Prototype Chapter (Rural, Two-Lane Roads) Crash Data Traffic Data Roadway Data

31 Crash Data - Required Crash History Data Frequency and Severity Data by Location and by Year

32 Traffic Data - Required Average Daily Traffic by location

33 Roadway Data – Horizontal Data Elements Tangent Simple Curve Spiral Curve Deflection Heading Coordinate Station Equation

34 Roadway Data – Vertical Data Elements Vertical Point of Intersection Elevation Tangent Curve

35 Roadway Data – Cross Section Data Elements Pavement (Cross Slope) Shoulder (Width and Type)

36 Roadway Data – Lane Group Data Elements Thru Passing Turn Two-way left-turn Climb

37 Roadway Data – Roadside Group Data Elements Driveway Density Hazard Rating

38 Intersection Data Traffic Control Number of Legs Intersection Sight Distance Number of approach lanes & volume Turn lanes Skew angle