Comparison of driving performance on-road and in a low-cost simulator using a concurrent telephone dialling task

Driving performance in an instrumented vehicle was compared with performanc e in a low-cost, fixed-based driving simulator. Six men and six women drove a freeway route while periodically dialling simulated phone calls. The sam e subjects drove a laboratory driving simulator using two visual fidelity l evels: a colour scene with relatively high detail, and a monochrome (night) scene showing only road-edge markings. Lane position, speed, steering-whee l angle and throttle position were recorded in both contexts. Lane-keeping in the simulator was less precise than on the road, but speed control perfo rmance was comparable. The SD of lane position in normal driving was about twice as large, on average, in the simulator (0.360 versus 0.165 m). Lane k eeping and speed control were less precise when dialling the phone than in normal driving, both in the simulator and on the road, but the performance decrement was greater in the simulator. The addition of the phone task incr eased the mean lateral speed in the car by about 43%, while in the simulato r the mean lateral speed increased by 158% with the addition of the phone t ask. Subjects > 60 years of age showed larger performance decrements during a concurrent phone dialling task than did subjects 20 - 30 years of age bo th in the simulator and on-road. No important differences in driving perfor mance were found between the high and low simulator scene fidelity levels. The simulator demonstrated good absolute validity for measures of speed con trol and good relative validity for the effects of the phone task and age o n driving precision.