Post on 12-May-2018
Highway Safety Analysis Tools for Engineers
Xiaoduan SunUniversity of Louisiana – Lafayette
Dan Magri
Hadi H. ShiraziLouisiana 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
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.
1. Louisiana Crash Data Analysis Program
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 on-
line 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
General Analysis
time
space
Factors
A Particula highway
frequency
Rate
any legnth
Advanced Analysis
Map control
crash report
Lon in
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?
Hit and run between 0 and 6am
Total hit and run
7% of total 2004 crashes
Had been drinking between 0 and 6am
Total # of “had been drinking” cases
Locations with one single
crash resulting 3 fatalities
77 crashes involved farm
equipments
76 Pedestrian fatalities
Red light running
So far, only safety performance function for
rural 2-lane highway is available from the on-
going project of Highway Safety Manual
Acknowledgement
Mr. Tom Richardson and Mr. Glenn Chustz from
Louisiana Department of Transportation and
Development.
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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
–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
Putting „Safety‟ in Its Proper Perspective
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
Safety Environmental Traffic Operations Right-of-Way CostsImpacts Impacts
•Traffic Noise
Model 1.0
•CAL3QHC
•Mobile 5a
•3-D Visualization
•CITYGREEN
•HCM
•MUTCD
•simulation
•Design
Specifications
•B/C analysis
methods
•Design
Criteria
(nominal
safety)
•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 do potential users want/
need?
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-the-
art’ 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 – Introduction and Fundamentals
Part II – Knowledge
Part III – Predictive Methods
Part IV – Safety Management of a Roadway
System
Part V – Safety Evaluation
Glossary
Part I - Chapter 1
Introduction and Overview1.1 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
Fundamentals2.1 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 6Special 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 Networks7.1 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
ObjectivesTo 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 SystemChapter 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
1st Safety Effects
2nd Safety Principles
3rd Measures of Safety
4th Methods to Predict Safety Impact
5th Decision-Making Tools
User Survey Results –Priority of Facility Types in HSM
1st Signalized Intersections
2nd Multilane Roads
3rd Two-lane Roads
4th Yield and STOP-controlled Intersections
5th 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