HEAVY VEHICLE DRIVER WORKLOAD ASSESSMENT. TASK 7B: IN-CAB TEXT MESSAGE SYSTEM AND CELLULAR PHONE USE BY HEAVY VEHICLE DRIVERS IN A PART-TASK DRIVING SIMULATOR

This report contains the results of a simulator study conducted to serve as a supplement to a National Highway Traffic Safety Administration (NHTSA) heavy vehicle driver workload field study. Its purpose was the evaluation of effects of cellular phone and text message display use tasks on driver-vehicle performance. Fourteen truck drivers participated and were asked to engage in three cellular phone dialing tasks (auto-dialing; local, 7-digit dialing; and long-distance dialing), two cognitive cellular phone tasks (responding to questions of a biographic nature or involving mental arithmetic), and seven CRT text message reading tasks (tachometer checking, time checking, radio tuning, 4-line reading, auto-dial, local-dial and long-distance dial). Driver-vehicle performance was also evaluated relative to traffic density. Results indicated that driver-vehicle performance varied with respect to each of the three kinds of in-cab tasks. Performance was also differentiated with respect to traffic density, although to a lesser extent. Of note is that the CRT reading tasks had a relatively more noticeable impact on driver-vehicle performance than did either the dialing or cognitive tasks. This report concludes with a comparison of simulator and on-the-road data collection results and prospects for future heavy vehicle driver workload assessments.