Expansion of NASS/CDS for characterizing run-off-road crashes

Abstract

Objective

Run-off-road (ROR) crashes account for one-third of all annual crash fatalities in the US. The National Automotive Sampling System Crashworthiness Data System (NASS/CDS) is a dataset which may be used to understand the nature of ROR crashes. Despite the wealth of coded data available in NASS/CDS, this dataset lacks coded information about the roadside environment and the off-road trajectory of the vehicle. This information would be useful for determining lane departure warning (LDW) benefits, residual safety problems, performance of current safety hardware, lane marking inventory, LDW test procedure development, radius of curvature characterization, and effectiveness of ESC. The purpose of this paper is to demonstrate a methodology for expanding the data available in NASS/CDS to form and validate a specialized road departure database.

Methods

Observed, measured, and reconstructed data elements were extracted from NASS/CDS and compiled into the National Cooperative Highway Research Program (NCHRP) 17-43 database. Observed variables were primarily coded from the scene photographs and included information such as the lane markings, and geometry of the roadside cross-section. Additional variables were measured from the scaled scene diagrams including the path of the vehicle, road dimensions, and roadside object positions. The vehicle impact speed and departure speed were reconstructed using the WinSMASH delta-v, roadside object characteristics, and vehicle path. Two studies were conducted to demonstrate the usefulness of the NCHRP 17-43 database in evaluating both vehicle-based and infrastructure-based ROR countermeasures.

Results

The resulting NCHRP 17-43 database includes 1,581 NASS/CDS cases representing 510,154 ROR crashes. Analysis of the database found that drivers which crashed following an overcorrection were younger than drivers which did not overcorrect. This may indicate that inexperienced drivers are more likely to overcorrect when departing the roadway. The 85^th percentile impact severity of ROR crashes, which occur on roads with a speed limit greater than 65 mph, is higher than the practical worst-case test conditions for roadside barriers.

Conclusions

The NCHRP 17-43 database contains information extracted from NASS/CDS cases to better understand the nature of ROR crashes, driver behavior in these crashes, and the potential benefits of both vehicle-based and infrastructure-based ROR countermeasures.

Keywords:

• Run-off-road crashes
• road departure crashes
• lane departure warning
• roadside barrier
• NCHRP 17-43 Database

Acknowledgements

The authors gratefully acknowledge the Transportation Research Board for funding this study. We wish to thank the NCHRP 17-43 project panel and Mark Bush, NCHRP Senior Program Officer, for their insights and feedback. Our thanks to the Virginia Tech students and research assistants who helped develop the database: John Arbolino, Kay Battogtokh, Kristen Dunford, Andrew J. Galloway, Joseph-Brandon Gopiao, Arnab Gupta, Daniel Gutierrez, Alexandra Haynes, David Holmes, Steven Hunter, Nick Johnson, Taylor Johnson, Katelyn Kleinschmdit, Alec Klevenhagen, Sydney Laverly, Elizabeth Mack, Stephanie Martinelli, Kellie Matthews, Kerri McBride, Jordan Moon, Kyle Naddeo, Kevin Ota, Jonathan Perdue, Dillon Richardson, Colin P. Smith, Daniel Surinach, Yvonne Teng, Jacob Valente, Robert Vasinko, and Kaitlyn Wheeler. We also gratefully acknowledge Chuck Niessner, our initial NCHRP Senior Program Officer on this project.

Data availability statement

The data on which this study was based are all publicly available as detailed in the paper.