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Guidelines for Slope Traversability

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TRB’s National Cooperative Highway Research Program (NCHRP) has released a pre-publication version of Research Report 911: Guidelines for Slope Traversability, which includes guidelines for determining the traversability of roadside slopes considering the characteristics of the current passenger vehicle fleet.

As part of development of this report, researchers performed full-scale traversability tests and compared the performance of the vehicles with the simulations performed for the same test conditions.

Rollovers are the leading cause of fatalities in single vehicle ran-off-road (SVROR) crashes. Analysis of six years of data from the National Automotive Sampling System Crashworthiness Data System indicates that 31% of SVROR crashes result in a rollover. Approximately 75% of these rollover crashes are initiated by vehicles digging into the ground on embankments or in ditches after encroaching onto the roadside.

Development of NCHRP Research Report 911 was prompted by concern that some roadside slope conditions that have for many years been considered traversable for passenger cars may not be traversable for light trucks. With the steadily increasing percentage of light trucks in the vehicle fleet, further research was needed to determine what should be considered as safe sideslope conditions for today’s vehicle fleet. Proper assessment of slope traversability may help reduce the number of rollover crashes and associated fatalities.


Suggested Citation

National Academies of Sciences, Engineering, and Medicine. 2019. Guidelines for Slope Traversability. Washington, DC: The National Academies Press.

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