Providing Infrastructure that improves Road Safety Bucharest, May 10-11, 2011

{ Road Safety Impact Assessment

Quantification Challenges for Worldwide Application

Basil Psarianos, Professor National Technical University of Athens, Greece

International Road Federation

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Directive 2008/96/EC on Road Infrastructure Safety Management ONLY for the Trans-European Road Network

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Road Safety Impact Assessment: A Proactive Design Decision Process for Road Safety

Road Safety Impact

Assessment

Road Safety Audits

Road Safety Inspections

Road Network

Safety Management

P R O A C T I V E

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Strategic Level of Decision Making for Road Design and Planning

New Roads and Substantial Modifications of existing Roads

Safety Implications of Design and Planning Alternatives

Safe Route Planning

All Road Projects

Prerequisite for Approval of any Road Project

Safety Considerations associated with Alternative selected

Cost-beneficial Component of Alternative

AIM of RIA for New & Old Roads

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Elements of a road safety impact assessment: (a) problem definition; (b) current situation and ‘do nothing’ scenario; (c) road safety objectives; (d) analysis of impacts on road safety of the proposed alternatives; (e) comparison of the alternatives, including cost-benefit analysis; (f) presentation of the range of possible solutions.

Elements to be taken into account: (a) fatalities and accidents, reduction targets against ‘do nothing’ scenario; (b) route choice and traffic patterns; (c) possible effects on the existing networks (e.g. exits, intersections, level crossings); (d) road users, including vulnerable users (e.g. pedestrians, cyclists, motorcyclists); (e) traffic (e.g. traffic volume, traffic categorization by type); (f) seasonal and climatic conditions; (g) presence of a sufficient number of safe parking areas; (h) seismic activity.

RIA Content

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Denmark

Germany

Finland

Lithuania

Netherlands

Portugal

Slovakia

RIA: An Old Story (more or less) for some Members States

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One Dimensional (Major Roadwork, Road Facility, Reconstruction) Engineering Judgment Literature Review Local Network Impact C-B Analysis

Two Dimensional (Areal Level) Baseline Situation (year 0) Future Situation w/o Measures (Autonomous

Development) Road Safety Alternatives C-B Analysis Optimization of Alternatives for best C-B ratio

Two Types of RIA

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The Achilles Heel: Quantification

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Road Safety?

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Safety Impact Assessment

There is actually NO Safety!

Instead there is RISK

RISK (R) is a combination of Crash Severity (SH) and its Probability (p):

R=SH*p or

d(SH)p(SH)R

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VII SEMINARIO

A:Local Entrance Street

B:Local Entrance Street

C:Shopping Street

D:Central Square

E:Shopping Street

F:Local Entrance Street

G:Local Entrance Street

Different Sections and Characters (after H. Heinz)

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Can Someone define EXACTLY for each Section the appropriate:

Design Speed?

Cross-Section?

Curvature?

Intersection Form and Type?

Equipment?

Traffic Characteristics?

ETC?

Safety Impact Assessment

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{

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Evidence-Based Road Safety: The conscientious and judicious use of current best evidence in providing

road safety for individuals, facilities, and transportation systems.

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Safety Impact Assessment

CrashesofNumber

VictimsofNumber

Exposure

CrashesofNumberExposureimpactRoadsafety

__

____

RISK LOSS

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Usual Prediction Model

• E(λ)=Expected Number of Accidents • Q=Traffic Volume for Major & Minor

Road • β=Elasticity • γi=Coefficients • xi=Risk Factors •

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Example: Motorways

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Accident Modification Factors (AMF)

Accident Modification Factor is a constant or equation that represents the change in safety following a change in the design or operation of a facility.

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Crash Reduction Factor: CRF

Crash Reduction Factor is a constant that represents the portion of crashes reduced as a result of a safety improvement (e.g., add a left-turn bay) at a specific location or along a specific road segment.

Crash Reduction Factor: CRF

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CRF:

CRF 1Nw

Nw /oCRF = crash reduction factor associated with a specific improvement; Nw = expected number of crashes with the improvement, crashes/yr; and Nw/o = expected number of crashes without the improvement, crashes/yr.

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Volumes change on Network: RIA on Network

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Volumes???

Motorway Korinthos-Patra

Motorway Attiki Odos

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Experience on Traffic Forecasts

Source: Halkias, B., Tyrogianni; H.:

PPP Projects in Greece: The Case of Attika Tollway, Route-Roads No. 342, 2008

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% Errors in Traffic Forecasts (Flybjerg et al., 2006)

underestimation overestimation

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GIS-Support Tool

Input

•Accident Data

•Network Data

•Road Characteristics

•User Behavior

•Etc

Intervention Scenarios

•Technical

•Juridical

•Etc

Output

•Total Costs of Measures

•Crash Modifications

•Presentation of Alternative Measures (scenarios) for comparison

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SEROES Expert System

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Safety Impact Assessment: Example

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Safety Impact Assessment: Example continued

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Safety Impact Assessment: Cost?

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Cost-Benefit Analysis By EZRA HAUER

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Cost-Benefit Analysis

By Ezra Hauer, TRB 2011

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Cost-Benefit Analysis

By Ezra Hauer, TRB 2011

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Cost-Benefit Analysis

By Ezra Hauer, TRB 2011

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Public Consensus: For Example Access Management

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Public consensus, ie is prohibition of property access possible?

Typical Example: people assess property rights higher than road safety

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Road Safety Impact Assessment

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RIA: Conclusions

QUANTIFICATION PROBLEMS

Knowledge Gap

Data Sets

Modelling

Calibration Factors

Statistical Evidence

Traffic Forecasting

CBA Weaknesses

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RIA: Conclusions

Setup a Plan and Action Program at International / EU and National / Local Level to address the quantification problems of Road Safety Impact Assessment and get the public consensus for it!

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RIA: Conclusions

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Engineer’s Role in Informal RIA Application

SAFETY: NOMINAL vs SUBSTANTIVE SAFETY i.e.

Guidelines vs Performance, or

Rhetoric vs Reality

FLEXIBILITY to make Professional Design Choices AND Assuming Responsibility for them

PRACTICAL DESIGN

RIA: Conclusions

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Basil Psarianos, Nat’l Tech. Univ. Athens, Greece

bpsarian@mail.ntua.gr

International Road Federation