This paper describes a system for the measurement of driving task difficulty. It entails the concurrent recording of driver performance on a secondary task, parameters of his physiological activity, steering control movements, vehicle speed and distance travelled. A binary choice, serial response task was selected. This scored in terms of omissions, errors and response times. The stimuli are tones of 690 Hz and of 70m sec duration, directed via headphones to either the left or right ear, in random order, at a constant rate of one every 1.5 seconds. The driver responds with his left foot by pressing either the left or right of two adjacent microswitches mounted beside the brake pedal. This response does not cause any peripheral interference with driving, since the research vehicle is fitted with automatic transmission. Heart rate and respiration rate were the two physiological parameters selected for measurement. Details are given of the data acquisition and data reduction equipment fitted on the 1967 ford fairlane v8 sedan, with automatic transmission, used in the experiment. The results of the preliminary studies showed that on a test track, secondary task response times and omissions decreased as lane width increased, over five different widths and in traffic, 84% of traffic events were associated with secondary task omissions and/or long response times. Details are given of a before-and-after evaluation of clearway parking restrictions in the city of adelaide, australia, using the system described above. Results of that study are outlined and discussed. For the covering abstract of the conference, see IRRD abstract no. 215031.
Abstract