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FHWA Highway Safety Programs

Chapter 2 – Data Collection and Analysis

Introduction

The SHSP is a data-driven process. All elements of the SHSP process, from development to evaluation, require States to analyze and make effective use of State, regional, local and tribal safety data.

Data enable managers to identify safety problems, select proper strategies and countermeasures, monitor progress toward achieving SHSP goals and objectives, measure the effectiveness of SHSP strategies, identify needed improvements, and direct limited resources to the highest potential for reducing fatalities and serious injuries. A variety of strategies can be employed to improve and collect data, perform analysis, and allow SHSP stakeholders access to the data and analysis. For example, States may qualify for a State Traffic Safety Information System Grant (NHTSA Section 405) for data improvement activities, such as improving the timeliness, accuracy, completeness, uniformity, integration, and accessibility of data that is needed to identify priorities for Federal, State, and local highway and traffic safety programs. In some States, multiple agencies provide funding for data collection and management through interagency agreements.

States should strive to improve the safety data needed to identify priorities for Federal, State, regional, tribal and local highway and traffic safety programs. When developing their SHSP, they should use the best available data to identify SHSP initiatives and plan data improvements, if needed.

To advance data gathering capabilities, States should develop an active partnership with the TRCC. TRCCs are responsible for identifying data system enhancement strategies that can affect access to data, as well as its accuracy and timeliness. FHWA and NHTSA data improvement programs, such as the Crash and Roadway Data Improvement Program (CDIP), the Roadway Data Improvement Program (RDIP), and NHTSA’s Traffic Records Assessments, also provide opportunities to improve data systems. They are designed to assess the strengths and weaknesses of State safety data systems and offer expert consultation and recommendations for corrections and other improvements.

Availability of complete and accurate crash data for all public roads is a critical highway safety issue. Some States identify the need to upgrade, improve, and standardize the traffic records information system as an emphasis area in the SHSP to improve the completeness and accuracy of the safety data. This makes safety data improvements a priority, which will lead to a better SHSP in the future.

Types of Data

A variety of data are available to support the development of SHSPs. These include the following:

  • Crash Data – Type of crash (lane-departure, intersection, rear-end, etc.), weather conditions, time of day, day of week, vehicle type, person type (driver, occupant, bicyclist, pedestrian, etc.), number and severity of injuries, traffic law violations, crash location, manner of collision, number of vehicles involved, alcohol or drug impairment, direction of travel, crash diagram, narrative description of the crash;
  • Injury Surveillance – EMS response time, hospital injury severity assessment, hospital length of stay and cost, rehabilitation time and cost;
  • Roadway and Traffic – Functional classification and ownership, roadway inventory data (i.e., roadway segment, intersection, ramp/interchange data), traffic control devices, location referencing system, rail grade crossings, structures (bridges, tunnels), traffic volume, locations that do not have an empirical history of fatalities and serious injuries, but possess risk factors for potential crashes, vehicle types on the roadway, road safety audit findings;
  • Vehicle – Vehicle Identification Number (VIN), registration information and plate, age/model/year, weight, owner information, Commercial Motor Vehicle (CMV) data (e.g., U.S. DOT number, carrier information, inspection/out-of-service records;
  • Driver – Age and date of birth, driver history (previous convictions and crashes), license status, gender, ethnicity, education, training;
  • Law Enforcement – Citations, prosecutions, convictions, sentencing, case tracking, adjudication; and
  • Other – Statewide occupant protection use survey, insurance data (carrier, policy number, claims cost), demographic data, etc.

The data may be collected from various sources, including State and local crash data systems and roadway inventory files, the National Fatality Analysis Reporting System (FARS), the General Estimates System (GES), the Motor Carrier Management Information System (MCMIS), the National Emergency Medical Services Information System (NEMSIS), the Crash Outcome Data Evaluation System (CODES), Federal Railroad Administration Highway-Rail Crossing Inventory Data, and others.

Data Integration

Data integration refers to connecting to, combining, and/or linking data residing in various systems to provide a unified view of the data. With respect to highway safety, data integration can help SHSP leaders better understand highway safety needs and develop effective strategies for addressing them. Currently, each State maintains a crash database to which local agencies are required to submit crash reports. However, crash data alone do not typically provide sufficient information on the characteristics of the roadway, vehicle, driver experience, or medical consequences. When crash data are linked to (or integrated with) roadway inventory, driver licensing, vehicle registration, citation, conviction, EMS, death certificate, census, and other data, it is possible to evaluate the relationship among the roadway, vehicle, and human factors at the time of the crash. Linkage to medical information clarifies level of injury and other crash outcomes. For example, plotting lane departure crashes by location can provide valuable information about where these crashes have occurred in the past. Combining lane departure crash location data with roadway inventory data (shoulder widths, rumble strips/stripes, cable median barriers, curve configurations, hills, etc.) provides greater understanding of the relationship between roadway configuration and lane departure crashes and enables SHSP leaders to develop effective strategies to reduce them. The integration of these two datasets (crash data and roadway inventory) provides more and better information than either of them provide individually. In addition, integrating databases promotes collaboration among the agencies, which can lead to data collection improvements.

Data Collection and Management

Safety data are fundamental to SHSP development. Data enable managers to identify safety problems, select proper strategies and countermeasures, monitor progress toward achievement of SHSP goals and objectives, measure the effectiveness of SHSP strategies, identify needed improvements, and direct limited resources to where they have the highest potential for reducing fatalities and serious injuries. Of all the data types needed to develop and evaluate an SHSP, perhaps the most frequently used are crash data. But other safety data (e.g., vehicle, roadway, behavioral) also can and should be used to effectively inform SHSP decisions.

Safety data collection is a complex process that requires collaboration among agencies, organizations, modes of transportation, and disciplines. One method for establishing collaboration is accomplished through the State TRCC, which facilitates project planning, coordination, and implementation designed to improve a State’s traffic records system and oversees the State Traffic Records Strategic Plan, which details the critical traffic records data issues. Typically, all levels of law enforcement are represented on the TRCC. Some States develop a data emphasis area team to work in collaboration with the TRCC to improve crash data collection, distribution, and management processes and to determine what data to analyze as well as appropriate analysis methods. This may help all involved organizations to not only understand the need for data improvements, but also to agree on the priority areas identified through data analysis.

Data Analysis

States must analyze the available safety data to identify the critical highway safety issues and safety improvement opportunities (23 U.S.C. 148(a)(12)(B)). The analysis is used to develop emphasis area goals, objectives, and strategies and action plans; monitor and evaluate results; and provide feedback for future updates to the SHSP.

Analysis can involve simple statistical investigations of crash trends, types, and contributing factors, or use advanced methods such as those presented in the Highway Safety Manual (HSM). The basic data analysis required to support the SHSP process is usually performed in-house. If States feel like they need additional data analysis assistance, this can often be provided by university research centers, other State agencies that work with similar data, etc. Data are used as a foundation for identifying SHSP priorities for the SHSP process and serve as the basis for the following:

  • Identification of emphasis areas – By identifying and describing safety problems quantitatively, an agency knows the magnitude of the problem and can focus its efforts on areas with the greatest potential to improve safety.
  • Identification of crash type – Data analysis is used to discern trends in the frequency of certain types of crashes (e.g., rear-end collisions, lane departures, impaired driving, etc.). Crash type data are used to identify SHSP emphasis areas and develop action plans.
  • Strategy and countermeasure selection and prioritization – Analysis of safety data helps managers to select and prioritize strategies and countermeasures. High priority should be given to those strategies and countermeasures that could significantly reduce highway fatalities and serious injuries in the key emphasis areas. Consideration also should be given to systemic safety improvements, which address high-risk roadway features that are correlated with specific severe crash types, rather than crash frequency. Low-cost countermeasures (e.g., rumble strips) are ideal to apply on a systemic basis.
  • Performance-based program management – Analysis of safety data allows managers to determine the extent to which the SHSP is achieving its goals and objectives.
  • Monitoring and evaluation – Data monitoring and evaluation helps managers make course corrections as the SHSP is implemented; develop new programs using more effective countermeasures and strategies; improve existing programs; and direct resources toward implementation of the most effective programs, policies, and projects.
  • Resource justification – Data-driven prioritized road safety projects provide transportation planners, engineers, law enforcement officers, and others with justification for additional resources.

Data Sharing

Local governments, MPOs, advocacy groups, and others require safety data for conducting safety planning and project-related activities. Some State agencies provide raw data, as well as filtered datasets that can be readily used by local agencies. Collaboration is fostered by providing stakeholders with access to safety data and training on analysis techniques. Data sharing also promotes local efforts to improve data accuracy.

Stakeholder access to reliable data helps provide consistency between the SHSP and other transportation and safety plans. Some effective and efficient data sharing practices include:

  • Provide a mechanism for State and local agency partners to access data (such as a data fact book or a web-based centralized data site) to promote the consistent use of data and information among partners;
  • Provide safety data and analysis to both internal and external partners;
  • Develop policies to establish data dissemination schedules;
  • Develop a standard procedure for handling data requests that clearly identifies who will manage requests and how they will be processed;
  • Host forums to discuss data issues and enhancement strategies (for MPOs, local agencies, etc.);
  • Encourage MPOs to conduct safety analysis for their member jurisdictions, including crash location mapping;
  • Work with the Local Technical Assistance Program (LTAP) personnel and others to support safety planning efforts at the local level by providing data for non-State highways;
  • Develop a highway basemap, which is a representation of all public roads that can be used to geolocate attribute data on roadways; and
  • Provide training to State and local agency partners on the collection and analysis of safety data to enhance their ability to generate and share reliable data.

Checklist

Following the recommended steps in the checklist below will help support the data collection, management, analysis, and sharing procedures necessary for developing an SHSP.

❑ Develop a data emphasis area team to collaborate with the State TRCC to improve crash data collection, distribution, and management processes and to determine what data to analyze as well as appropriate analysis methods.

❑ Analyze the available data to identify critical highway safety issues, safety improvement opportunities, and emphasis areas.

❑ Provide a mechanism for State and local agency partners to access consistent data (such as a data fact book or a web-based centralized data site).

❑ Conduct forums to discuss safety data issues and enhancement strategies.

❑ Provide safety data and analysis to internal and/or external partners to support safety efforts.

❑ Encourage MPOs to conduct safety analysis for their member jurisdictions.