ITE Midwest District Annual Meeting

Session 6 - June 30, 2015

Richard C. Coakley, P.E., PTOE

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Why Produce This Document?

•Safety seen as incompatible with CSS approach

•Need to integrate safety (not just “consider” it)

•Safety for all users and throughout all phases

•New tools like HSM allow for quantifying safety

•Decision makers strive for appropriate balance

“By quantifying the safety implications and by applying context sensitive and flexible design principles, the highway designer, safety engineer, planning team, and general public can make the best possible decisions for their community”. Foreword, p. iii

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Document Purpose

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Provides best practices to transportation agencies and professionals so that they can apply the most appropriate technical knowledge on quantitative safety performance—crashes and their outcomes—to develop projects for a range of highway and street types and contexts.

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Informational Report – What it is •Information on tools, best practices and resources to incorporate safety into the project development process

•Continuation of work related to Designing Walkable Urban Thoroughfares: A Context Sensitive Approach (ITE/FHWA)

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Informational Report - What it is Not

•A design rule book

•A new standard

•A replacement of the other resources

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Report Structure •Chapter 1 – Introduction

•Chapter 2 – Safety in the PDP

•Chapter 3 – Organizational Needs

•Chapter 4 – Planning and Programming

•Chapter 5 – Engineering and Design

•Chapter 6 – Construction

•Chapter 7 – System Management/Operations

•Chapter 8 – System Preservation/Maintenance

•Chapter 9 – Tort Liability, Risk Management

•Chapter 10 – Case Studies

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Introduction, Overview and Organizational Considerations

Figure 2-1

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Integration of Substantive Safety into Project Development

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Figure 2-4

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Key Concepts

•Nominal safety is the use and adherence to engineering standards and practices

•Substantive safety is the performance of the street or highway as measured by frequency of traffic crashes and their outcomes (severity).

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Nominal vs. Substantive Safety

Figure 2-2

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“The direct application of established design criteria or standards (i.e., nominal safety) is no assurance that a certain quality of design (i.e., level of substantive safety) will be achieved—indicating that such criteria are not sufficient in themselves.”

—Jack E. Leisch, “Dynamic Design for Safety,” ITE, 1972

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Planning and Programming

Figure 4-1

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Key Steps

•Problem/need identification

•Data collection and analysis

•Project formulation

•Programming and prioritization

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Substantive Safety Analysis & Tools

Application of Substantive Safety Analysis and Tools

Four Steps of Transportation Planning and Programming

Analysis Applications Problem/Need Identification

Data Collection and Analysis

Project Formulation

Programming and Prioritization

Network screening

Diagnosis/crash analysis

Road safety audits

Countermeasure development

Economic analysis

Roadway design context considerations

Design element considerations

Alternative analysis with predictive models

Highly useful and important analysis task

Moderately important task

Potentially useful task depending on circumstances

Table 4-4

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Data Needs • MMUCC: Model Minimum Uniform Crash

Criteria

• MMIRE: Model Minimum Inventory of Roadway Elements

…… both are scalable to an

agencies staff and

available resources

National Cooperative Highway Research Program, Research Results Digest 329

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Decision Making Framework

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Figure 4-2 Federal Highway Administration, Safety Focused Decision-Making Guide

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Programming and Prioritization

•Ranking

•Incremental benefit/cost analysis

•Optimization

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Engineering and Design

Figure 5-1

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Stages of Design and Engineering

Figure 5-2

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Substantive Safety Analysis & Tools

Application of Substantive Safety Analysis and Tools to Engineering and Design

Analysis Applications/Tools

Engineering and Design Steps

Scoping/Planning Preliminary Engineering

Final Engineering

Network screening Diagnosis/crash analysis Road safety audits Countermeasure development Economic analysis Roadway design context considerations

Design element considerations

Alternative analysis/ predictive models

Design exceptions

Value engineering assessment

Constructability/maintenance of traffic

Highly useful and important analysis task

Moderately important task

Potentially useful task depending on circumstances Table 5-1

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Safety and Environmental Analysis

•Include a safety analysis commensurate with complexity

•Use best available safety data specific to location

•Use best available information and tools

•Dialogue with the public and key stakeholders

•Address potential construction safety issues

•Apply innovative techniques to address speeding or impaired driving

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Safety Planning Process

Figure 5-4

Federal Highway Administration, Integrating Road Safety into NEPA Analysis

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Design for Crash Prevention

•Upgrading to standards should not be an absolute

•The principles of substantive safety are appropriate for selection and evaluation of design criteria

•An understanding of the design variables

•Insight into context sensitive design elements facilitates engineering judgment

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Typical Design Decisions

•Access vs. mobility

•Pedestrian vs. motor vehicles

•Bike lanes vs. parking lanes

•Commuters vs. freight haulers

•Private vehicles vs. transit vehicles

•Through vs. local access

•Purpose and Need vs. safety

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Integration with Engineering & Design

Sources to Integrate Safety into the Three Engineering and Design Steps

Tools and Resources Project

Scoping/Planning Preliminary Engineering Final Design

Crash Modification Factor Clearinghouse

Enhanced Interchange Safety Analysis Tool (ISATe)

Highway Safety Manual Part B Roadway Safety Management Process

Highway Safety Manual Part C Predictive Models

Highway Safety Manual Part D Crash Modification Factors

Interactive highway Safety Design Model (IHSDM)

NHCRP 17-38 Spreadsheets—HSM Predictive Methods

Road Safety Audit (RSA), Road Safety Audit Review (RSAR)

Roadside Safety Analysis Program (RSRAP)

Safety Analyst—HSM Part B Analysis Tool

Integrating Road Safety into NEPA Analysis: A Primer for Safety and Environmental Professionals

Mitigation Strategies for Design Exceptions

NCHRP Report 500: Guidance for AASHTO Strategic Highway Safety Plan

NCHRP Report 600 Human Factors Guidelines

Road Side Design Guide

Toolbox of Countermeasures for Rural Two-Lane Curves

Mitigation Strategies for Design Exceptions

Table 5-2

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Example: Superelevation

Substantive Safety Considerations Controlling Criteria

Design Element Substantive Safety Principles Safety Effects

Superelevation Horizontal curves are superelevated to reduce the friction demand and steering effort required of the driver. The superelevation on high speed horizontal curves helps drivers maintain control, thereby reducing the likelihood of lane departure crashes.

The HSM has a CMF for superelevation on 2-lane rural roads. On other facilities the effect on crash frequency based on superelevation is unknown.

In urban conditions superelevation is not an influencing factor on substantive safety.

From Table A-1

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…. Safety Effect

Potential Crash Effects of Improving Superelevation Variance of Horizontal Curves on Rural Two-Lane Roads [16, 35] for Rural Two-lane Highways

Treatment Traffic Volume Crash Type (Severity) CMF

Improve Superelevation Variance < 0.01

Unspecified All types

(all severities)

1.00

Improve 0.01 < Superelevation Variance < 0.02

= 1.00 + 6 (SV-0.01)

Improve Superelevation Variance > 0.02

= 1.06 + 3 (SV-0.02)

Base Condition: Superelevation variance <0.01.

American Association of State Highway and Transportation Officials, Highway Safety Manual

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Example: Lane Width

Substantive Safety Considerations Controlling Criteria

Design Element Substantive Safety Principles Safety Effects

Lane Width The primary safety concerns with reductions in lane width are crash types related to lane departure, including run-off road crashes. Wider lanes are beneficial to substantive safety for two primary reasons: Wider lanes increase the average

separation between vehicles in adjacent lanes.

Wider lanes provide more room for driver correction in near crash circumstances.

Lane width affects safety differently for varying roadway types. It is a factor in safety performance for rural 2-lane, 2-way roadways and rural multilane highways, but not for urban and suburban arterials. The CMFs for lane width are based on average annual daily traffic volume (AADT) and generally the predicted number of crashes increases with decreased lane width and with increased AADT. On high-speed, rural 2-lane highways, the risk of

cross-centerline head-on or cross-centerline sideswipe crashes increases with decreasing lane width affecting driver ability to stay within the travel lane.

For 2-lane, 2-way roadways, lane widening will reduce crash frequency. The effects of this reduction begin to diminish between 11 and 12 feet, with the effects on widening above 12 feet to be negligible.

From Table A-1

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…Safety Effect

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Cra

sh M

od

ific

atio

n F

acto

r

AADT (veh/day)

0 400 800 1,200 1,600 2,000 2,400 1.00

1.10

1.20

1.30

1.40

1.50

1.60

1.70

The factor applies to single-vehicle run-off-the-road and multiple-vehicle head-on opposite-direction sideswipe, and same-direction sideswipe crashes.

1.50 9-ft Lanes

1.30 10-ft Lanes

1.05 11-ft Lanes

1.00 12-ft Lanes

Figure 5-8 American Association of State Highway and Transportation Officials, Highway Safety Manual

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Construction

Figure 6-1

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Traffic Management Approaches Traffic Management Approaches

Work Zone Short-Term

Maintenance Resurfacing Patching/

Repair 3R Project Reconstruct

in Place

Reconstruct New

Alignment

Close one lane while work is conducted

● ● ●

Use flaggers with one way operation

● ● ●

Long-term lane closure for multi-lane highway

● ● ● ●

Long-term multi-lane closure ● ●

Shoulder or lane closure for adjacent work

● ● ●

Temporary work access ● ●

Construct temporary road/lanes ●

Close road sign USE ALT ROUTE ●

Close road with signed detour route

●

Table 6-1

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Application of Substantive Safety to Construction

•Road Safety Audits

•Performance Monitoring and Evaluation

•Transportation/Traffic Management Plans

•Work Zone Enforcement

•Visibility and Training

•ITS

•Work Zone Traffic Control

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Transportation System Management and Operations

Figure 7-1

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Integration of Safety into TSM&O

•Safety data collection, analysis, and management

•Development review

•Problem identification and diagnosis

•Countermeasure development and recommendations

•Monitoring and evaluation

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System Preservation and Maintenance

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Figure 8-1

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“The fact that new design values are presented herein does not imply that existing streets and highways are unsafe, nor does it mandate the initiation of improvement projects . . . For projects of this type (resurfacing, restoration, or rehabilitation [3R]), where major revisions to horizontal and vertical curvature are not necessary or practical, existing design values may be retained.” —AASHTO, A Policy on Geometric Design

of Highways and Streets

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Tort Liability and Risk Management

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Professional engineering analysis and design

judgment during project development are

necessary to manage risk, regardless of whether one

adheres strictly to standards

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Risk Management: Best Practices

•Decision Making - A process that considers alternative treatments can be more important than the selection of a particular treatment itself.

•Documentation - the decision-making process must be fully documented to record the policy and engineering bases upon which those decisions are made.

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Risk Management: Best Practices

•Design Exceptions - documents the decision-making process when a particular design feature does not fit neatly within existing policies, standards, warrants, or guidelines

•Continuing Evaluation - provides a sound basis for evaluating the effectiveness of its decisions and better informs future decisions

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In Summary…..

The science of substantive safety provides quantitative estimates of roadway safety, which can be successfully used in project

development and the detailed comparison of the effectiveness of safety

improvements.

The Informational Report will be published and available at http://www.ite.org/css/

This Informational Report has been published by ITE

It is available online at: http://library.ite.org/pub/e4edb88b-bafd-b6c9-6a19-22e98fedc8a9

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Questions