A COMPARISON OF TIME-TO-CONTACT, TIME-TO-ARRIVAL, AND TIME-TO-COLLISION, IN TWO ROAD-SIDE ENVIRONMENTS AND ON STRAIGHT AND CURVED ROADS
 
Godley, S. and Hesketh, B., University of Sydney, Australia
 
In driving, time and speed estimations of our own and other vehicles are extremely important in many situations, including left-turn and over-taking maneuvers. These judgments include a driver's estimations of when an approaching vehicle will reach his or her position, both when the driver is stationary (time-to-contact) and moving (time-to-collision), and a driver's estimates of when his or her own vehicle will reach a position on the road ahead (time-to-arrival). Past research had not contrasted these three judgments, and very little is known about how the road-side environment and road curvature influenced these estimations. Eighteen licensed drivers drove a simulator at three speeds (stationary, 60 and 100 kph), and estimated when they should have reached the same position as approaching vehicles which disappeared 2.5 seconds before they met, and which were traveling at three speeds (stationary, 60 and 100 kph). Time estimations were made in a highly textured and built-up urban environment, and a low contrast open rural environment, whilst positioned on straight roads, left curves and right curves. Judgments were generally underestimated, and time- to-contact estimates were more accurate than time-to-collision estimates, which were more accurate than time-to-arrival estimates. When the participant was moving (but not stationary), estimates were more accurate (less underestimated) in the rural environment than the urban environment, but mostly only on straight roads and not on curves. Judgments were also more accurate on right curves than left curves. Implications of these results will be discussed.