SafetyAnalyst Michael S. Griffith FHWA July 2003

2 What is SafetyAnalyst? Vision Statement Provide state-of-the-art analytical tools for use in the decision making process to identify and manage a systemwide program of site-specific improvements to enhance highway safety by cost- effective means

3 Why is SafetyAnalyst Being Developed? Both FHWA and participating state highway agencies have perceived a need to improve the analytical tools available to highway agencies for safety management of the highway system

4 Participating States

5 Who is Developing SafetyAnalyst? Federal Highway Administration Technical Working Group, 13 participating states Midwest Research Institute and subcontractors ITT Industries, Software development contractor

6 Tools for Safety Management To assist agencies in making better decisions about: Where to make highway safety improvements Determining what improvements to make Evaluating the effectiveness of implemented safety improvements

7 Target Audience Professionals involved in deciding: Where to make highway safety improvements Determining what improvements to make Evaluating the effectiveness of implemented safety improvements

8 Scope Addresses site-specific improvements based on site-specific needs, not general programs like vehicle design improvements, occupant restraints, etc. Uses state-of-the-art technology to advance the state of the practice Should be comprehensive – including all stages of the safety management process

9 What Tools will be Available in SafetyAnalyst? Network screening to identify sites with promise for safety improvement Diagnosis of safety concerns Selection of countermeasures Economic appraisal of countermeasures Priority ranking of countermeasures Evaluation of implemented projects

10 Network Screening Review entire roadway system or selected parts – roadway segments, intersections, ramps, railroad grade crossings, etc. Identify sites with promise for safety improvement Rank sites with promise for safety improvement Select sites as candidates for diagnosis

11 Types of Network Screening Basic network screening Screening for high proportions of specific target accident types Detection of safety deterioration Screening for high frequency of specific target accident types Screening for corridors with promise

12 Basic Network Screening Two screening approaches: –sliding window –peak searching Two measures of potential for safety improvement: –expected accident frequency –expected excess accident frequency

13 Diagnose Safety Concerns at Selected Sites Consider both sites with promise identified by network screening tool and from other sources Identify accident patterns Investigate causal factors Consider site conditions and safety performance from engineering and human factors viewpoints Assess whether a potentially correctable safety concern exists

14 Select Appropriate Countermeasures Present lists of countermeasures that are potentially appropriate for identified accident patterns and safety concerns Final selection made by user Where appropriate, user may select: –combination of countermeasures –alternative countermeasures for economic appraisal and priority ranking

Economical Appraisal and Priority Ranking Assess the cost-effectiveness of candidate countermeasures Rank candidate countermeasures to assist choices among them Select an optimal program of countermeasures to maximize systemwide safety benefits

Types of Economic Appraisal Cost-effectiveness EPDO-based cost-effectiveness Benefit-cost ratio Net benefits

Optimization Considers multiple sites selected by the user User specified total budget constraint Optimization routine selects countermeasures to maximize safety benefits within budget constraint

Evaluation Assess the effectiveness of countermeasures based on a formal before-after evaluation Evaluation results should be suitable for future use as AMFs in SafetyAnalyst

19 Scope of Evaluation Evaluation types: –percent change in accident frequency –change in proportion of target accident types

20 How Will Safety Analyst Be Implemented? SafetyAnalyst will be implemented as a set of integrated software tools to perform key steps in the safety management process SafetyAnalyst will be made available to highway agencies by FHWA SafetyAnalyst will be maintained as the state of knowledge advances

21 What Is the Planned Schedule? “New Approaches to Highway Safety Analysis“ training course – Fall 2003 Release interim tools – 2004 Release final tools – 2006

22 SafetyAnalyst Website