Systematic control study was made of passing judgment in situations where sight distance is a limiting factor. A passing car and a lead car were employed in the experiment. The experiment was conducted at the Vineland speedway, a 1.5-mile closed-road racing circuit in Vineland, new jersey. The passing car and the lead car were each equipped with fifth wheels to provide speed and fine distance information. The subjects in the experiment were 24 Philadelphia yellow cab co. Drivers, ranging in age from 26 to 58, with a minimum of 9 years of driving experience. The experiment was conducted to determine which cues a driver is sensitive to in making a pass/no-pass decision in a flying pass situation in which remaining sight distance is the limiting factor. Results indicate that drivers are responsive to all of the variables that determine the validity of the passing decision: the speed of the passing car, the passing car-lead car closing rate, the distance of the passing car from the end of the passing zone, and the passing car-lead car headway. While drivers were not able to compensate perfectly for speed and closing rates, it is clear that they did respond appropriately to these variables by passing more at shorter distances when passing-car speed was low and closing rate was high. Drivers were able to compensate partially for errors of judgment by increasing their speed and passing in less time when a marginal passing opportunity was accepted. The data suggest that there would be little to gain by reducing the variability associated with distance and headway judgment.
Abstract