Need for Revised Total Eyes-Off-Road Criterion in the NHTSA Distraction Guidelines: Track Radio-Tuning Data

Abstract

This study re-analyzes participant-level glance data from a NHTSA-sponsored test track study of nine radio-tuning tasks in five radios. NHTSA stated that in its judgment, all nine tasks met the definition of traditional manual radio tuning, and so collapsed the data across all participants to estimate an 85th percentile. NHTSA further stated that it combined that track percentile with the 85th percentile from a radio-tuning task in a separate simulator study, to set its total-eyes-off-road time (TEORT) acceptance criterion. Given NHTSA’s statements, individual radio-tuning tasks should, in general, meet the criteria created from them. This study performed such an analysis, and found that this expectation was not met. Four out of nine radio-tuning tasks did not meet the criterion. One problem is that NHTSA did not allow for variability in its 85th percentile estimate. Additionally, TEORT values were higher in the simulator than track for the same task with age-matched data, meaning that if the track tasks had been run in the simulator then the 85th percentile TEORT may have been higher. These issues illustrate the need for revising the criteria based on an improved analysis of the data that NHTSA used to set those criteria. Without doing so, many commonly-accepted secondary tasks (including manual radio tuning in many vehicles) would not meet the current NHTSA Guidelines glance criteria. Revised criteria should be derived in a way that would provide the needed consistency with age-balance requirements of task-acceptability testing, as well as allowing robustness for variability in the percentile estimates.