PENNSYLVANIA DEPARTMENT OF TRANSPORTATION

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PENNSYLVANIA DEPARTMENT OF TRANSPORTATION

USING SPATIAL TOOLS TO ANALYZE CRASH AND ROADWAY DATA PROJECT

RFQ NO. 06-05 (C08)

FINAL REPORT

Draft Final Report on a research project to define a methodology that will help PennDOT "take highway safety to the next level".

Prepared by:

February 25, 2008

1. Report No.

2. Government Accession No.

FHWA-PA-2008-002-060508

4. Title and Subtitle

Using Spatial Tools to Analyze Crash and Roadway Data, Project Number 0605(08)

Technical Report Documentation Page 3. Recipient's Catalog No.

5. Report Date February 25, 2008 6. Performing Organization Code

7. Author(s) Gannett Fleming, Inc. (J. Cichocki, A. Sarvis)

8. Performing Organization Report No. GF Project Number 048026

9. Performing Organization Name and Address

Gannett Fleming, Inc. PO Box 67100 Harrisburg, PA 17106-7100

12. Sponsoring Agency Name and Address

The Pennsylvania Department of Transportation Bureau of Planning and Research Commonwealth Keystone Building 400 North Street, 6th Floor Harrisburg, PA 17120-0064 15. Supplementary Notes

10. Work Unit No. (TRAIS)

11. Contract or Grant No. 355I01-060508 13. Type of Report and Period Covered Final Report February 2007 ? February 2008

14. Sponsoring Agency Code

16. Abstract PennDOT engaged Gannett Fleming to conduct research into best practices in the use of geospatial analysis tools for highway safety analyses. The goals of the effort were to define a methodology for PennDOT to follow in identifying the best candidate locations for highway safety improvements, and to develop a Proof of Concept to test the proposed methodology. After conducting interviews and workshops involving more than 35 of PennDOT's stakeholders in highway safety processes, Gannett Fleming interviewed highway safety managers in five other state and federal highway agencies to determine what innovative tools and practices are currently being used. Gannett Fleming `s research also included a review of literature related to the study from more than 80 sources. Based on Gannett Fleming's research and analysis, PennDOT selected the "Highway Safety Data Relationships Knowledge Base" for further research. The knowledge base is an information repository based on concepts in data mining and expert systems. It uses advanced statistical analysis methods and expert business knowledge rules to discover data patterns based on correlation and other forms of relationships in the data. The knowledge base can be applied to diagnosing specific combinations of data attributes and features that may indicate the causative factors among homogeneous populations of crashes. Most highway safety data analyses involve studying correlations among multiple data sets. The knowledge base is an innovative and comprehensive tool for such an application. It provides a framework for identifying and managing relationships among many combinations of data sets that are useful in highway safety analyses. Gannett Fleming proceeded to develop a prototype as a proof of concept. Gannett Fleming demonstrated the prototype using actual PennDOT crash data. Three analysis scenarios were demonstrated: evaluating safety programming alternatives for alcoholinvolved crashes, diagnosing data patterns of crashes at a selected highway location, identifying potential sites for system-wide deployment of a selected countermeasure.

17. Key Words Highway safety Crash data analysis Safety Management Spatial analysis Geospatial analysis

Data mining Knowledge base Data pattern recognition Statistical correlation K-means cluster analysis

18. Distribution Statement No restrictions. This document is available from the National Technical Information Service, Springfield, VA 22161

19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages

22. Price

Unclassified Form DOT F 1700.7

Unclassified (8-72)

25 Reproduction of completed page authorized

Using Spatial Tools to Analyze Crash and Roadway Data Final Report

Table of Contents

1 Introduction ........................................................................................2

1.1 Document Purpose ......................................................................................... 2 1.2 Document Organization ................................................................................ 2 1.3 Version Information....................................................................................... 3

2 Final Report Context and Background............................................4

2.1 Statement of Problem.................................................................................... 4 2.2 Project Objectives .......................................................................................... 4 2.3 Task A Analysis ............................................................................................... 5 2.4 Task B Analysis ............................................................................................... 6 2.5 Task C Analysis ............................................................................................... 9

3 Proof of Concept Defined ..................................................................12

3.1 Decision History for the Knowledge Base Proof of Concept ................. 12

3.1.1 Presentation of Proof of Concept Options........................................................12 3.1.2 Other Decision Considerations..........................................................................13

3.2 Overview of the Knowledge Base Proof of Concept ............................... 13

3.2.1 What is a Knowledge Base?.............................................................................14 3.2.2 What are the benefits of a Knowledge Base?...............................................14 3.2.3 How is a Knowledge Base Used? ......................................................................15 3.2.4 Knowledge Base Specifications ........................................................................16 3.2.5 Proof of Concept Requirements and Design.................................................18

4 Proof of Concept Results and Implications .....................................19

4.1 Analysis of the Proof of Concept Results ................................................. 19 4.2 Implications of Results to PennDOT's Safety Analysis Process ........... 21

4.2.1 Process Areas where the Knowledge Base is Applicable ...........................22 4.2.2 Implications for Wider Implementation of the Knowledge Base .............23

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Using Spatial Tools to Analyze Crash and Roadway Data Final Report

1 Introduction

1.1 Document Purpose

This document is the deliverable report for Task E: Final Project Report in the research project titled "Using Spatial Tools to Analyze Crash and Roadway Data" (RFQ Number 06-05 (C08). This document provides a summary of the data inventory, interviews/research, and methodology selection phases of the project and provides details and results from the Task D proof of concept. Based upon the results of this project, PennDOT's vision for the future of the proof of concept is also presented.

In many ways, the Pennsylvania Department of Transportation (PennDOT) has been a national leader in the use of information technologies for highway safety data analysis. The Bureau of Highway Safety and Traffic Engineering (BHSTE) has continued to aggressively pursue new approaches to applying technology tools in its crash reduction goals. In 2006 PennDOT authorized a project to extend its capabilities in the application of geospatial information technology for crash data analysis. GeoDecisions was awarded the contract to execute the "Using Spatial Tools to Analyze Crash and Roadway Data" project as part of a larger program conceived by the Safety Management Division in BHSTE to "take safety to the next level".

The purpose of this research project was to explore new methods of applying geospatial technologies to analyze crash and roadway data producing meaningful information to support Pennsylvania's highway safety goals. The scope of work included performing research through literature review and interviews of other transportation agencies to determine what innovative tools and practices are currently being utilized for the same reasons that PennDOT was seeking. The project scope also included defining a methodology for PennDOT to follow in identifying the best highway locations for safety improvements, and testing that methodology via proof of concept.

After completing the research, GeoDecisions identified several alternative methodologies, from which PennDOT selected the Highway Safety Data Relationships Knowledge Base. GeoDecisions tested the Knowledge Base by developing a prototype for proof of concept. GeoDecisions demonstrated the proof of concept using PennDOT's crash data. The demonstration pointed out how the Knowledge Base met the criteria established earlier during the research phase of the project. This document is a report on the project performance.

1.2 Document Organization

This document contains four sections, plus appendices: ? 1. Introduction ? Defines the purpose of the document, and provides an overview of the document contents and version information.

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Using Spatial Tools to Analyze Crash and Roadway Data Final Report

? 2. Final Report Context and Background? Presents the primary drivers and background for the project, previous project tasks (Tasks A ? C), and an overview of the Task D proof of concept.

? 3. Proof of Concept Defined ? Presents a review of the decision rationale for choosing the Knowledge Base Proof of Concept and an overview of what a knowledge base is.

? 4. Proof of Concept Results and Recommendations ? Presents an analysis of the Proof of Concept results and recommendations for extended implementation at PennDOT.

1.3 Version Information

Version Num.

Edit Date

Edited By

0

November 30, 2007 J. Cichocki,

A. Sarvis

1.0

February 8, 2008 J. Cichocki,

A. Sarvis

1.0

February 25, 2008 J. Cichocki

Comments Preliminary Outline Draft Final Approved Final document

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Using Spatial Tools to Analyze Crash and Roadway Data Final Report

2 Final Report Context and Background

2.1

Statement of Problem

The Pennsylvania Department of Transportation (PennDOT) is responsible for continually maintaining and improving the safety of the Commonwealth's transportation network. Addressing this responsibility requires successful development and implementation of processes to: identify and analyze the locations and contributing factors of crashes; select locations that have the highest potential for improvement; evaluate possible countermeasures and their probable impact on safety; and track the effectiveness of implemented countermeasures. The tangible and measurable success of this goal are stated clearly in PennDOT's Comprehensive Strategic Highway Safety Improvement Plan (CSHSIP) which calls for reducing traffic fatalities in the Commonwealth to 1.0 per 100 million vehicle miles traveled by 2008.

The perpetual need for improved processes and tools means that PennDOT must constantly look at industry trends and best practices for new opportunities. Modern geographic information systems (GIS) and database software show great potential for integrating and analyzing crash and roadway data. PennDOT has used its existing crash location clustering algorithms for many years now, but is specifically interested in identifying new spatial analysis tools that can be used to support its safety improvement processes.

PennDOT does have an extensive set of established and effective crash analysis tools and methodologies including, crash databases, the spatial query tool CDART, algorithms for developing Location Priority Lists, and customized file of standard engineering countermeasures. In order to best address the problem of highway safety, PennDOT needs to leverage these existing tools and datasets, including spatial data/tools, to provide better information for decision making. All of these existing datasets, tools and processes are core components for crash location analysis at PennDOT, but each provides a foundation and opportunity for potential improvement through the use of new "state of the practice" tools.

2.2

Project Objectives

In light of the need for continual highway safety improvements, and in recognition of the new compliance requirements of SAFETEA-LU, PennDOT entered into this project to investigate new methods to improve crash data analysis capabilities and produce meaningful information to support the States highway safety goals.

The project was organized into multiple tasks intended to methodically gather requirements and expectations, and research "state of the practice" spatial tools for highway safety analysis. Comprehensive research began with a review of PennDOT's safety analysis goals; current crash and roadway data; and current crash analysis processes. It also included research into the processes being used by other state and

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Using Spatial Tools to Analyze Crash and Roadway Data Final Report

federal government agencies and to assess the capabilities available through commercial-off-the-shelf (COTS) GIS and spatial database products. The information gathered during these tasks was intended to establish candidate tools for an improved approach for identifying locations where safety improvements are needed. From these candidates a tool was selected and then tested by conducting a Proof of Concept analyses. This organized approach for discovering new highway crash analysis tools is detailed in each of the sections below.

2.3 Task A Analysis

A review of PennDOT's current safety Analysis capabilities and future expectations established the technology/data foundation and comprehensive safety analysis themes that were of significant interest to PennDOT's Bureau of Highway Safety and Traffic Engineering staff.

The first project task was intended to capture the current status of PennDOT's safety analysis capabilities from both headquarters and district personnel to collect their ideas and impressions for new tools or improvement to existing tools. With that objective Task A documented PennDOT's current safety analysis tools, procedures and datasets and collected the expectations and goals of the Bureau of Highway Safety and Traffic Engineering (BHSTE) staff for the future of safety analysis at PennDOT.

PennDOT's Strategic Safety Goals and Objectives were developed as part of the CSHSIP that defines specific safety focus areas and sets goals for reduction of highway fatalities. The goals of PennDOT's CSHSIP provide the basis for most of the safety analysis expectations discovered during the PennDOT interviews of this task. Another primary expectation, relevant to the discovery of spatial tools, was that PennDOT's investment in CDART would be leveraged and not simply augmented and/or duplicated by a new tool.

In addition to expectations, the PennDOT interviews yielded a range of other common safety themes that contribute to a comprehensive safety analysis process. These themes included:

? Dissect/rank/prioritize known clusters: Closer examination of clusters to discover why crashes of a given type occurred with such frequency. Need to discern to what degree the conditions at that location make it a candidate for applying certain countermeasures.

? What factors matter in prioritizing clusters?: Need a way to looking for new ways to interrogate their databases to extract the most significant factors in crash causation and location ranking.

? Pattern recognition: Would like software that proactively scan the database and look for patterns that reveal the nature of crash history as it relates to road configuration, driver population, highway usage, and any number of other factors.

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Using Spatial Tools to Analyze Crash and Roadway Data

Final Report

? Combine linear and intersection clusters: A clustering algorithm should be able to analyze crashes that are spatially related, regardless of roadway network configurations.

? Include safety engineering and "soft side": Future safety analysis methodologies and tools need to support all types of countermeasure programs not just engineering.

? Integrate non-transportation data: Future methodologies should include other environmental factors such as land use and demographics.

? Integrate prescribed countermeasures: Future analysis tools should include the concept of tracking safety engineering and soft-side countermeasures applied to roadway locations where crash clusters have been previously identified.

? Utilize cost/benefit data: Evaluate the cost of a proposed countermeasure versus the potential societal benefit of the expected reduction in crashes within a safety analysis system environment.

? Integrate performance metrics: Inclusion of data that measures the effectiveness of countermeasures would complete the safety management system cycle. This would provide management with useful information for high-level planning, and it would provide critical input to advanced predictive modeling tools.

? Analyze cluster data for systemic improvements: When countermeasures are shown to be effective in crash reduction, PennDOT wants to identify other locations where there is the likelihood that the same countermeasure will have the same positive effect.

The ultimate goal of these common themes is to improve the department's ability to proactively address highway safety issues rather than deal with them in a reactive manner. Additional details of PennDOT's specific safety goals, initiatives, expectations and existing crash analysis resources can be found in the Task A report.

2.4 Task B Analysis

Literature review and state/federal interviews, guided by PennDOT's areas of interest, found that there were no "commercial off-the-shelf" spatial tools for safety analysis, that FHWA's Safety Analyst application does not yet contain significant spatial capabilities, and that other state DOT's efforts toward spatial tools do not exceed PennDOT's current capabilities. Based upon best practice findings, key themes for specific low cost safety improvements and new alternative analysis methodologies were presented.

Task B compiled literature reviews, Web searches, and DOT and Federal Highway Administration (FHWA) interviews to summarize the current best practices in crash analysis and safety improvement. The literature review examined over 80 sources, and included analysis of documents generated by the Transportation Research Board (TRB), the American Automobile Association (AAA), and a state survey done by the Arizona DOT. Research also included a review of the FHWA's pooled fund project to develop

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