The National Academies

NCHRP 17-43 [Active]

Long-Term Roadside Crash Data Collection Program

  Project Data
Funds: $1,000,000
Staff Responsibility: Mark S. Bush
Research Agency: Virginia Polytechnic Institute and State University
Principal Investigator: H. Clay Gabler
Effective Date: 4/27/2010
Completion Date: 6/30/2016

Roadside crashes account for 35 percent of the fatalities on the nation's highways. Safety professionals have strived to address this problem and have had some success. Continued improvement in roadside safety will depend on improved understanding of the conditions that lead to injuries and fatalities during ran-off-road crashes. There is a fundamental need to collect better and more detailed information about roadside crashes and the conditions under which they occur. The National Automotive Sampling System (NASS) Crashworthiness Data Subsystem (CDS) has collected detailed information on vehicles and occupants for a strategically selected sample of crashes across the country since 1979. This data collection system was designed to provide information regarding vehicle safety performance, and it has proven to be very valuable in developing vehicle countermeasures to reduce the risk of injuries and fatalities in highway crashes. However, the NASS-CDS program collects very little data on the roadway, roadside, and safety features at the site of ran-off-road crashes limiting its usefulness for the analysis of roadside crashes.  Some recent research studies have supplemented the NASS data with road features data for selected crashes. NCHRP Project 17-22 (published as NCHRP Report 665, Identification of Vehicular Impact Conditions Associated with Serious Ran-off-Road Crashes), gathered supplemental roadway and roadside data for selected NASS CDS cases, and the crashes were reconstructed to estimate the impact conditions. It also incorporated the data gathered in NCHRP Project 17-11, Determination of Safe/Cost Effective Roadside Slopes and Associated Clear Distances, and the FHWA Rollover Study to increase the size of the database.  A plan for a long-term accident data collection program was also developed under Project 17-22. The Project 17-22 plan advances the concept of an ongoing, detailed crash data base. This database may incorporate other data, particularly those from new research efforts. While this database will be helpful in answering some current questions, ongoing collection of data will help address the changing fleet, road design, roadside hardware features, and traffic conditions and provide a significant data set for future research.  For example, the data could be used to establish some of the following distributions and relationships: 
  • Optimal longitudinal barrier length of need.
  • Factors associated with crashes related to trees and utility poles.
  • Factors associated with rollovers on slopes.
  • Safety performance of all common roadside safety features to provide highway designers with more objective criteria for safety hardware selection.
  • Link between occupant compartment deformation and occupant risk in ran-off-road crashes.
  • Occupant risk associated with partial rollovers by vehicle class.
  • Link between impact conditions and probability of injury for common safety features and roadside hazards.
  • Distribution of vehicle trajectories and the effects of roadside slopes on vehicle trajectories.
  • Relationship between impact angle and crash severity for longitudinal barriers.
  • Effects of curbs, ditches, and other terrain irregularities placed in front of safety hardware on the probability of injury during a crash.
  • Distributions of impact conditions, including speed, angle, and vehicle orientation, as a function of highway type or functional class.
  • Improved severity indices for the Roadside Safety Analysis Program (RSAP).
This list is by no means exhaustive, but it serves to illustrate the many unanswered questions that can be addressed with in-depth crash data. An area of particular importance is the development of an improved procedure to determine the length of need (LON) for longitudinal barriers that considers site-specific conditions and is consistent with the philosophy of only installing barriers that present less risk to the traveling public than the roadside obstacle being shielded. This improved procedure should be rational, simple to apply, and provide consistent, cost-effective results. This will promote greater uniformity of LON application across the country.
The objectives of this project are to (1) supplement the long-term crash data collection program created under NCHRP Project 17-22, (2) investigate options for modifying the database and linking it with other relevant databases, (3) demonstrate the types of analyses that would be possible with a detailed database of roadside crashes, (4) develop an improved procedure for determining longitudinal barrier length of need, and (5) recommend procedures for ongoing collection and management of the database. This research should provide solid evidence that demonstrates the value of having a long-term, detailed roadside crash database that can provide an in-depth, continually growing, data resource applicable to solving roadside safety problems.
(1). Review the long-term data collection process and protocols developed under NCHRP Project 17-22. The review shall include content and structure of the database, the protocols for supplemental roadway data collection, the procedures used for crash reconstruction, and the robustness of the various analyses undertaken using the database to date. (2). Assess the adequacy and appropriateness of the Project 17-22 database components to address the types of roadside issues identified in the Background section of this Research Project Statement.  For example, given that the Project 17-22 database focuses on serious roadside crashes, assess how the absence of lower severity crashes may affect potential applications of the database. (3). Identify data elements missing from the Project 17-22 database that are needed to address the identified roadside issues.  For the missing data elements, identify potential sources for these data and propose a process for linking the identified data to the Project 17-22 database. (4). Propose a work plan for using the Project 17-22 and other identified databases to assess how crash risk, impact severity, and site conditions affect optimal length of longitudinal barriers. Also propose a work plan for developing an improved procedure for determining longitudinal barrier length of need.  (5). Propose work plans for using the Project 17-22 and other identified databases for analyzing the factors associated with (1) crashes related to trees and utility poles, (2) rollovers on slopes, and (3) two additional issues as recommended by the contractor.  (6). Develop a work plan for ongoing data collection to supplement and enhance the Project 17-22 database.  The work plan shall include appropriate quality control techniques, consider any procedural changes identified in the above tasks, and include recommendations for long-term management and dissemination of the data. Periodic updates of the database are expected.  A summary of the descriptive statistics shall be provided with each update of the database. (7). Submit an interim report that summarizes the findings from Tasks 1 through 6, including the work plans and associated budgets. (8). Meet with the NCHRP panel to review the Task 7 interim report approximately 1 month after its submittal. Submit a revised interim report addressing the panel’s review comments. (9). Execute each of the approved work plans. (10). Conduct an annual presentation on the findings of the project to an appropriate roadside safety committee designated by the NCHRP. (11). Submit a final report that documents the entire research effort and includes a recommended plan for long-term data collection and dissemination. Detailed documentation of the database shall be included in the final report.
STATUS: The interim report was received in June 2012 and was approved.  Phase 2 of the research is in progress.  The TRB NHTSA MOU is for providing the cooperation and coordination of crash data collection between this NCHRP research project and NHTSA efforts through June 2016.

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