Older-Driver Foot Movements

NHTSA - Behavioral Safety Researchhttps://doi.org/10.21949/15259202017PDFTech ReportLococo, Kathy H.Staplin, LorenMastromatto, TiaBrooks, Johnell O.Srinivasan, RaghavanSifrit, Kathy J.TransAnalytics, LLCClemson University. International Center for Automotive ResearchUniversity of North Carolina at Chapel Hill. Highway Safety Research CenterUnited States. Department of Transportation. National Highway Traffic Safety Administration. Office of Behavioral Safety ResearchUnited States. Department of Transportation. National Highway Traffic Safety AdministrationUnited StatesAged driversBrakesCamerasCognitive impairmentCountermeasuresCollisionsDriversInjuriesPedalsPedal application errorspedal misapplicationunintended accelerationsafetyolder driversdriver performancefunctional abilitieshuman factorsmedical conditionsperipheral neuropathymild cognitive impairmentorthopedic surgeryResearch HubDOT HS 812 431DTNH22-11-D-00223, Task Order No. 02Final reportThis study explored how drivers 60 and older control the accelerator and brake while driving and parking. It built upon the findings of a study documenting the prevalence and characteristics associated with pedal misapplication crashes (Lococo, Staplin, Martell, & Sifrit, 2012). Researchers measured functional ability, and used an instrumented vehicle on a test route in actual traffic to obtain measures of foot movement and positioning that could be expected to affect the likelihood of a pedal error. Participants included two medical status groups: (1) a medical conditions group comprised of six drivers with peripheral neuropathy of the feet and two drivers with a recent right hip replacement, and (2) a group of 18 normally aging drivers. Researchers also documented participants\u2019 height, and femur and tibia length to determine whether these factors were related to pedal control. An additional objective was to learn how older drivers positioned their seat in relation to the brake, and whether poor vehicle fit was associated with stature, tibia or femur length, leg functional reach, and/or driver sex.Anthropometry, rather than medical status group, accounted for the majority of significant differences in foot movements; differences by sex were also observed. Short stature and shorter tibia and/or femur length were related to lifting the foot during the transfer from accelerator to brake (rather than pivoting), more efficient foot movements, longer foot hover time, and foot placement on the brake closer to the center of the pedal. Females were more likely to lift the foot, while males pivoted. Females had faster transfer time and foot placement closer to the center of the brake. Normally aging participants pressed the brake slightly harder than those in a medical conditions group. There were no differences between groups in on-road performance. However, drivers with medical conditions scored significantly poorer than the normally aging drivers while parking. A logistic regression found that leg functional reach (but not sex, height, or any other individual lower limb measure), was significantly related to goodness of fit; as leg functional reach decreased, the probability of good fit decreased. Pedal extenders may be a solution for drivers who must fully extend their legs to reach their pedals to maintain a safe distance from the airbag. Power adjustable pedals as standard equipment would permit better fit for all drivers, without the inconvenience of acquiring and installing pedal extenders, especially for multiple-operator vehicles. Education to reinforce safe seat positioning for every trip is also recommended.129