This study examined factors associated with mobile device use (MDU) while driving in commercial motor vehicle operations. Analyses were performed on a naturalistic truck driving data set that involved 100 drivers operating a commercial truck that had been instrumented with data collection equipment, including video cameras. The focus of the analysis reported here was twofold. First, how does the MDU recorded in naturalistic driving video compare to the estimates of MDU from the National Occupant Protection Use Survey (NHTSA 2011)? Second, does MDU vary as a function of time-of-day? Regarding the first issue, based on video inspection, it was determined that participants used a handheld phone approximately 4.3% of the time and a hands-free phone 4.0% of the time (totaling 8.3% of the driving time). When cell phones, Citizen’s Band radios, and dispatching devices were included, it was found participants used devices 10.4% of the time. Considering time of day of MDU, one analysis binned the data to match circadian rhythm high (9 a.m. and 7 p.m.) and low (1 p.m. and 2 a.m.) points. Across the four bins, the highest proportion of MDU (accounting for exposure) occurred in the early morning (2 a.m.) bin. Results of additional analyses similarly provide support for the hypothesis that truckers may use a mobile device as a countermeasure to drowsiness. (Author/publisher)
Abstract