Highway Safety Analysis Tools for Engineers Xiaoduan Sun University of Louisiana Lafayette Dan Magri Hadi H. Shirazi Louisiana Department of Transportation and Development The 2007 Louisiana Transportation Engineering Conference Baton Rouge, February 12, 2007
Topics 1. Louisiana Crash Data Analysis Program 2. Introduction to Highway Safety Manual
1. Louisiana Crash Data Analysis Program Highway Safety Analysis: a data driven activity As with all other aspects of transportation engineering, highway safety analysis is becoming more data driven, since data provide the most meaningful guidance in how, where, and what happened in the real world - if they are accurately collected. The technology advancements in recent years have greatly enhanced the efficiency and quality of crash data collecting process, which makes safety analysis more data-dependent and reliable.
Program Goal Provide a crash data analysis tool for the everyday traffic engineers in Louisiana who need to perform safety analysis periodically but have no extensive experience in database and GIS applications
Overview of the Program Development Phase I Phase II Phase III Objectives Develop a computer program for accident analysis on a GIS platform Make program an online application and further improve the program to include many newly proposed functions Add more analysis functions such as selecting, prioritize, and evaluating the countermeasures, and including urban area crash data and independent intersection crash analysis Summary of the accomplishments Developed the first version of a computer program for Louisiana crash data analysis on a GIS platform, and developed techniques to incorporate video image from the state bi-annual pavement survey. Finished on-line application; reprogrammed the system for flexible analysis unit (segment length) and user defined analysis scheme; applied HSM[ prediction model to the selected segments on Louisiana rural two-lane highways. HSM on-going
An on-line application program
Scope of Crash Data Analysis Program Conventional crash analysis Spatial (where are the most promising sites) Temporal Characteristics Combination of all factors Black Spot identification Safety performance evaluation Prediction vs. historical observation (rural two lane highways) Most Promising location identification
Results Presentation Charts Tables GIS maps Video
Program s Main Functions Lon in General Analysis time space Factors A Particula highway frequency Rate any legnth Advanced Analysis Map control crash report Analysis Unit: a highway, a segment of highway (by control section or by user defined length), an intersection, or a network
Total crashes on rural 2-lane highways Fatal crashes on rural 2-lane highways
Where are these fatal crashes?
Total hit and run 7% of total 2004 crashes Hit and run between 0 and 6am
Total # of had been drinking cases Had been drinking between 0 and 6am
Locations with one single crash resulting 3 fatalities
76 Pedestrian fatalities 77 crashes involved farm equipments
Red light running
So far, only safety performance function for rural 2-lane highway is available from the ongoing project of Highway Safety Manual
Acknowledgement Mr. Tom Richardson and Mr. Glenn Chustz from Louisiana Department of Transportation and Development. The crashed server will be back to operation Please leave your email for getting the address soon
2. The Development of Highway Safety Manual
Overview 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 HSM user survey results
Is this road safe or unsafe?
What about these alternatives? Is one safer than the others? What about these choices? How do we address the safety of these design options?
How do we make judgments about balancing safety with other community values? Safety vs. Costs, environment, etc.
Trade-offs We Routinely Make Capacity versus safety Permitted versus protected signal phasing Right turn on Red Economics versus safety 2-lane versus 4-lane rural highways 4-lane undivided versus divided highways Access control (driveway permits) Modal choice versus safety Rumble strips versus shoulder use by bicyclists
Putting Safety in Its Proper Perspective We routinely trade off safety in many decisions we make (ADMIT OR NOT) Safety is more than an abstract notion If safety is important and it varies, we should commit to including measures of safety in our evaluations
Two Ways to Look at Safety as Highway Engineers and Planners Nominal Safety is examined in reference to compliance with standards, warrants, guidelines and sanctioned design procedures (e.g., The Green Book) Substantive Safety is the actual or expected crash frequency and severity for a highway or roadway (i.e., its actual performance)
Complex decisions require meaningful tools for all important criteria Design Criteria (nominal safety) Traffic Noise Model 1.0 CAL3QHC Mobile 5a 3-D Visualization CITYGREEN HCM MUTCD simulation Design Specifications B/C analysis methods Safety Environmental Traffic Operations Right-of-Way Costs Impacts Impacts
What do potential users want/ need? Understand fundamental substantive safety principles Perform substantive safety analyses Methods to predict substantive safety (including and particularly issues involving choices on the margin ) Decision-making tools
What is the Highway Safety Manual (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. Synthesis of validated highway research Adapted & integrated to practice Analytical tools for predicting impact on road safety
The vision of the HSM -- a document akin to the HCM Definitive; represents quantitative state-of-theart information Widely accepted within the professional practice of transportation engineering Science-based; updated regularly to reflect research
Targeted Users of the HSM Primarily users: Front-line decision makers Analysts studying the effect of actions on road users Planners, designers and those responsible for the operations and maintenance Secondary users: Management Educational Institutions
History (1) Started with discussions within TRB about role of safety in Highway Capacity Manual Conference Session at TRB s January 1999 Annual Meeting concluded: The absence of, and the need for a single authoritative document to use for estimating safety impacts December 1999 Workshop confirmed: The crucial need for a stand-alone document to be named the Highway Safety Manual
History (2) Formation of a TRB Joint Subcommittee for the development of a HSM: Members of sponsoring committees AASHTO, FHWA, ITE Meetings since January 2000: About 100 members and friends Status 2003: Task Force (with six subcommittees)
Research & Development Task Force key objective to provide direction and oversight of research Relevant NCHRP effort: 17-25: CRFs for Traffic Engineering & ITS Improvements 7/06 17-26: Part III: Urban & Suburban Arterials 2/07 17-27: Parts I & II (Intro & Knowledge) 5/07 17-29: Part III: Multi-lane Rural Highways 7/06 17-34: Parts IV & V (Safety Systems & Evaluation) 9/06 17-36: Production of the First Edition 2008 Other related initiatives IHSDM, SafetyAnalyst, Human Factors Guidelines
A New Era in Highway 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
Outline of HSM First Edition Part I Part II Part III Part IV Part V Glossary Introduction and Fundamentals Knowledge Predictive Methods Safety Management of a Roadway System Safety Evaluation
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
Part I - Chapter 2 Fundamentals 2.1 What is Safety? 2.2 How Road Safety is Measured 2.3 Safety Performance, Crash Causation, Countermeasures, Accident Modification Functions 2.4 Human Factors in Road Safety 2.5 Traffic Exposure, Traffic Mix and Demand Management 2.6 Speed and Safety 2.7 Safety Evaluation
Part II - Chapter 3 Roadway Segments 3.1 Safety Effects of Design Elements 3.2 Safety Effects of Traffic Control and Operational Elements 3.3 Pedestrian and Bicyclist Safety on Roadway Segments 3.4 Safety Effects of Other Elements
Part II - Chapter 4 Intersections 4.1 Safety Effects of Design Elements 4.2 Safety Effects of Traffic Control and Operational Elements 4.3 Pedestrian and Bicyclist Safety at Intersections 4.4 Safety Effects of Other Elements
Part II - Chapter 5 Interchanges 5.1 Safety Effects of Design Elements 5.2 Safety Effects of Traffic Control and Operational Elements 5.3 Pedestrian and Bicyclist Safety at Interchanges 5.4 Safety Effects of Other Elements
Part II - Chapter 6 Special Facilities & Geometric Situations 6.1 Railroad-Highway Grade Crossings 6.2 Work Zones 6.3 Bridges 6.4 Tunnels 6.5 Two-way Left-turn Lanes 6.6 Passing Lanes/Short Four- Lane Sections on Two-Lane Highways 6.7 Climbing Lanes 6.8 Emergency Escape Ramps 6.9 Rest Stops 6.10 High Occupancy Vehicle Facilities 6.11 Reversible Roadways & Lanes 6.12 Weaving Areas 6.13 Collector-Distributor Roads 6.14 Frontage Roads 6.15 Transit Facilities and Related Features 6.16 Bicyclist and Pedestrian Facilities and Related Features 6.17 Toll Plazas 6.18 Special Events
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 7.8 Transitions between Highway Facility Types 7.9 Security (against Crime) and Safety
Part III - Chapter 8 Rural, Two-Lane Roads 8.1 Introduction 8.2 Methodology 8.3 Applications 8.4 Example Problems 8.5 References 8.6 Appendices
Louisiana Involvement Application of Highway Safety Manual Draft Chapter: Louisiana Experience -Journal of TRR, Published in 2006 Objectives To evaluate the model with data from Louisiana to assess the model s capability and transferability in predicting safety performance of rural 2-lane highways.
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
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
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
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
Challenges to HSM Development Must have good liaison with the potential user community Must be cognizant to highway agency concerns about tort liability Substantial funding and time needed to produce the first edition HSM
User Survey Background A web survey conducted in 2002 by User Liaison and Support Subcommittee Over 2000 invitations 288 complete responses
User Survey Results Employment Type
User Survey Results Participant Affiliation
User Survey Results Priority of Topics in HSM 1 st Safety Effects 2 nd Safety Principles 3 rd Measures of Safety 4 th Methods to Predict Safety Impact 5 th Decision-Making Tools
User Survey Results Priority of Facility Types in HSM 1st 2nd 3rd 4th 5th Signalized Intersections Multilane Roads Two-lane Roads Yield and STOP-controlled Intersections Interchanges
User Survey Results Applications for HSM System-wide and Planning Programs Integration with Training, University Courses, and Association References Prepare Responses to Citizens & Politicians A Daily Reference A Professional Handbook (Interfacing with a Software)
Acknowledgements HSM Task Force for the preparation of this part of presentation
Questions? xsun@louisiana.edu Thank You!