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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

Driver Brake and Accelerator Controls and Pedal Misapplication Rates in North Carolina

After a 2010 study of the phenomenon of unintended acceleration (UA), the National Highway Traffic Safety Administration (NHTSA) found that pedal misapplication could be a cause of many UA claims, specifically when drivers intend to apply the brake but instead apply the accelerator. Consequently, NHTSA determined that it would be worthwhile to study elements of vehicle pedal design and location to see if they might contribute to the propensity for pedal misapplication. Previous research efforts into UA hypothesized that certain design criteria such as lateral separation, the horizontal gap between the brake and accelerator pedal, and the distance between the surface planes of the brake and accelerator may contribute to driver error. As an exploratory effort, NHTSA conducted a quantifiable study of the relative locations of pedals in a limited set of passenger cars at its Vehicle Research and Test Center (VRTC) to determine whether elements of vehicle pedal design and location contribute to the propensity for pedal misapplication. Vehicles from populations of low and high rates of pedal misapplication were selected and dimensional variables as defined by an industry standard were measured. Since it was the only source of such comprehensive information, make and model information for pedal misapplication events were taken from the North Carolina State Crash Database. A NHTSA software program was used to define vehicle groups that were substantially similar based on factors such as brand, model, and vehicle wheelbase. North Carolina vehicle registration records were used to limit the vehicles studied to passenger vehicle groups with over 100,000 model-years of exposure in the State with high misapplication rate (HMR) and low misapplication rate (LMR). Ten HMR models and 10 LMR models were selected for study. In addition, 12 models were selected for special interest, including vehicles with the highest exposure that did not fall in either of the previous groups, vehicles similar to HMR or LMR models with significantly different rates, and a vehicle that was the subject of a previous investigation into pedal misapplication. Three vehicles of each model were located and measured. A statistical correlation of the measurements was conducted and for the first stage of the study, only vehicle dimensions were considered. No single variable had a high correlation to the misapplication rate, though stepover and accelerator position were the most correlated. Standard stepwise regression procedures produced an R2 value of 0.476, indicating a general relationship. After exhausting pedal variable data, a second analysis was performed that added variables regarding driver characteristics including age, height, and gender. This improved the model significantly and produced an overall R2 of 0.94. The addition of this data also inverted the correlation with stepover by indicating that higher stepover may specifically be related to higher pedal misapplication rates for older drivers, though this does not suggest that low stepover is not an issue for drivers in general. The results of the study indicate that adding driver characteristics with pedal dimensions affects the predicted rate and that optimal pedal dimensions for one demographic may not be optimal for another.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 52p

Subject/Index Terms

Filing Info

  • Accession Number: 01567287
  • Record Type: Publication
  • Report/Paper Numbers: DOT HS 812 058
  • Files: HSL, TRIS, ATRI, USDOT
  • Created Date: Jun 26 2015 1:41PM