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ENCE688F andHighway Safety Manual

Dr. Mohamadreza BanihashemiSenior Transportation Research Engineer II

GENEX Systems

University of Maryland SeminarNovember 2014

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Seminar BreakdownENCE688F: Highway Safety Fundamentals• History and Trends• Definitions and Concepts• Crash Studies and Crash Data• Crash Prediction Models• Major National Highway Safety Programs, HSM and SHRP2• Software Packages, Databases (i.e., SHRP2 RID) • IHSDM, a Course Project

Implementation of the HSM in the IHSDM Software• Highway Safety Manual (HSM) Overview• IHSDM Overview• Relationship between HSM and IHSDM• Use of IHSDM / HSM in Developing a Sustainable Highway System • Questions / Discussion.

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ENCE 688F:Highway Safety Fundamentals

A Graduate Course Focusing on Highway Safety History and Trends Definitions and Concepts Crash Studies and Crash Data Highway Safety Quantitative Evaluation Crash Prediction Models Major National Highway Safety Programs Software Packages, Databases (i.e.,

SHRP2 RID) Course Project (IHSDM Software).

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This is not

A Highways Safety Manual Course, or

An IHSDM Software Course, or

A SHRP2 Safety Program Training.

This is a Course in Highway Safety Fundamentals including many components of the above!!

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History and TrendsOrganizations: Federal Highway Administration (FHWA)

● Federal-Aid Program

● MUTCD

● Software/Website Development

● Actively Supporting HSM

Transportation Research Board (TRB)● Highway Safety Manual (HSM) 1st Edition

● SHRP2

● Toward HSM 2nd Edition

American Association of State Highway and Transportation Officials (AASHTO)● Highway Safety Manual (HSM)

● Some Other Programs

● HSM Publication and Support.

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History and Trends -Continue

● Highway Crash Fatality Trend● The First Period of Rising Automobile Use in the US● First National Conferences on Street and Highway

Safety ● Balanced Design for Safety, Design Speed Concept ● Early Studies on the Effect of Highway Geometry on

Safety ● An Erroneous Study Result: “The Accident Prone

Driver” ● National Programs of Research and Development.

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Definitions and Concepts

Introducing main highway safety concepts and measures: Design Speed Concept and its Deficiencies Nominal Safety Measures Substantive Safety Measures Surrogate Safety Measures (Diagnostic

Safety)• Operating Speed• Near Crash.

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Definitions and Concepts -Continue

Major Factors Known as Causes of Crashes

• Human• Vehicle• Highway• Environment

Cause and Effect vs. Correlation• Older drivers and crash severity• Speed and crash severity.

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Crash Characteristics

Highway Purpose and Functional Classification• Mobility vs. Access

Functional Classification Effects on Highway Design

Design Factors Affecting Safety the Most

Some National Crash Characteristics and Trends.

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Highway Characteristics and Safety

Major Highway Characteristics by Functional Class Traffic Volume Traffic Control Highway Geometry Auxiliary Lanes Roadside Lighting Speed Enforcement.

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Intersection/interchange Characteristics and Safety

Major Intersection Characteristics by Functional Class Volume Traffic Control Intersection Layout/Skew Angle Interchange Configuration Turn Lanes/Islands Lighting.

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Roundabout, A New Type of Intersection

Traffic Circles (Rotaries) Neighborhood Traffic Circles Modern Roundabouts

• Yield control• Channelization• Geometric curvature to limit the speed

Safety Effect of Replacing Intersections with Roundabouts

New Researches on Roundabouts.

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Types of Crash Data and Crash Studies

Observational vs. Experimental Data Longitudinal vs. Cross Sectional Data Panel Data Before-and-After Data Some Sources for Inconsistencies and

Biases Basic Types of Highway Safety Studies

• Naïve and Improved Before-After Studies• Cross Sectional Studies• Empirical Bayes Studies.

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Crash Data, Sources National highway Traffic Safety

Administration (NHTSA)• National Automotive Sampling System (NASS)• Fatality Analysis Reporting System (FARS)• Crashworthiness Data System (CDS)• General Estimates System (GES)

Highway Safety Information System (HSIS)

Other State Data GIS Data NDS Data Collected in SHRP2 Project.

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Common Types of Crash Prediction Models

Main Assumptions• Crash count obeys Poisson probability law• Estimates of crashes follow Gamma distribution

Most Common Models• Negative Binomial• Linear and Non-Linear Regression

Models with Crash Modification Factors• Safety Performance Functions• Crash Modification Factors

Empirical Bayes Process.

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Highway Safety Manual (HSM)

Part A – Introduction & Fundamentals• Chapter 1 Introduction and Overview• Chapter 2 Human Factors in Road Safety• Chapter 3 Fundamentals

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.

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More on Highway Safety Manual (HSM)

Part C – Predictive Methods• Chapter 10 Rural, Two-Lane Roads• Chapter 11 Rural, Multilane Highways• Chapter 12 Urban/Suburban Arterial Highways

Part D – Accident Modification Factors• Chapter 13 Roadway Segments• Chapter 14 Intersections• Chapter 15 Interchanges• Chapter 16 Special Facilities & Geometric Situations• Chapter 17 Road Networks

Part C – HSM Supplement• Chapter 18 Freeways• Chapter 19 Ramps.

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SHRP2 Safety Program

A Quick History What Is Naturalistic Driving Study (NDS)? Collecting NDS Data SHRP2 Roadway Information Data (RID) Collecting and Assembling RID Using NDS in Conjunction with RID Brain Storming.

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Course Project, IHSDM Software

Highway Safety Concepts Used in Each Module

Setting Attributes Mechanics of the Software A Quick Review of Administrative Tool Running the IHSDM Software Reporting and Customizing Report

Templates Interpretation of Results.

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Questions ?

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Highway Safety Manual (HSM) Part C Implemented in IHSDM

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HSM, Background, History, and Future

Joint Task Force sponsored by several TRB committees Partnership Among AASHTO, TRB and FHWA $7 Million/10 year research program Thousands of hours of volunteer effort of reviewing AASHTO Joint Task Force with members from Safety,

Design and Traffic Engineering Publication of the HSM by AASHTO (2010), Supplement

(2014) A new TRB Committee (Highway Safety Performance) Works to complete HSM 1st Edition and moving toward 2nd

Edition.

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HSM Partitions into

Part A Introduction,

Human Factors, and

Fundamentals

Part B Roadway

Safety Management

Process

Part C Predictive Method

Part D Crash

Modification Factors

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Concepts

Nominal Safety Substantive

Safety

Examined in reference to compliance with standards, warrants, guidelines and sanctioned design procedures

The expected or actual crash frequency

and severity for a highway or roadway

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What is IHSDM? A product of FHWA’s Safety Research and

Development Program A suite of software tools that support

project-level geometric design decisions by providing quantitative information on the expected safety and operational performance

Free Distribution and Support, First Release 2003, Latest Release 2014.

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Evaluation Modules

Crash Prediction Policy Review Design Consistency Intersection Review Traffic Analysis Driver/Vehicle

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Crash Prediction Module

Faithful implementation of the HSM Part C

Estimates expected crash frequency (i.e., Substantive Safety) as well as crash severity based upon roadway geometry and traffic volumes.

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Relationship between IHSDM and the HSM

A. Introduction and Fundamentals

B. Roadway Safety Management Process

C. Predictive Method (IHSDM CPM)Chapter 10: Rural, Two-Lane RoadsChapter 11: Rural, Multilane HighwaysChapter 12: Urban & Suburban ArterialsChapters 18 and 19: Freeways and Ramps. Recently published as supplements to the 1st edition of the HSM.

D. Crash Modification Factors.

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CPM / HSM Part C Scope

From AASHTO Website: An Introduction to Highway Safety Manual

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CPM / HSM Part C Scope - Continue

HSM Chapter Urban Rural

18 Freeway Segments 10 Lanes 8 Lanes

18 Speed-change Lanes 10 Lanes 8 Lanes

19 Ramps and C-D Roads

2 Lanes 1 Lanes

19 Ramp Terminals 7 Types 7 Types

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Models Components

Safety Performance Functions (SPFs) Crash Modification Factors (CMFs) Empirical Bayes (using crash history data) Calibration Factors

• Enter via IHSDM Administration Tool.

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Maximizing Safety Improvement Benefits in A Sustainable Highway System

Cost, the Factor in Decision Making • Construction Cost• Operational Costs, Users Cost • Environmental Costs• Crash Cost.

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Maximizing Safety Improvement Benefits in A Sustainable Highway System Continue

Network-level Maximization, Part B of the HSM

From AASHTO Website: An Introduction to Highway Safety Manual

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Maximizing Safety Improvement Benefits in A Sustainable Highway System Continue

Project-level Maximization, Part C of the HSM

Predicting Crashes for Different Alternatives Estimating Construction, Operational,

Environmental, and Crash Costs for Different Alternatives

Search for the Alternative with the Minimum Total Cost.

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Other IHSDM Modules, Policy Review

Checks roadway segment geometry against relevant design policy and “flags” variations.

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Other IHSDM Modules, Design Consistency

Estimates 85th percentile speed profile along alignment to evaluate operating speed consistency.

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Other IHSDM Modules, Traffic Analysis

Traffic simulation model (TWOPAS)

Estimates traffic quality of service measures.

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Other IHSDM Modules, Driver / Vehicle

Simulates driving behavior and vehicle dynamics on a two-lane highway

Provides profiles of predicted speed and other response variables, via a simulation of a single driver/vehicle combination.

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Other IHSDM Modules, Intersection Review

Expert system that applies rules of good practice in a comprehensive diagnostic review of a single intersection

Identifies possible safety concerns and typical treatments.

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IHSDM 2014 Release (10.0.0)

May be downloaded free-of-charge at: http://www.ihsdm.org

Technical support: • E-mail: IHSDM.Support@fhwa.dot.gov• Phone: (202)-493-3407

IHSDM Training (Offered by NHI): • FHWA-NHI-380071 On-site Course• FHWA-NHI-380100 Web-based Course

(http://nhi.fhwa.dot.gov )