Weighting waiting: Evaluating perception of in-vehicle travel time under moving and stopped conditions

Experiments are described in which traditional computer-administered stated-preference (SP) data are compared with virtual experience SP data to ascertain how people value stopped delay compared with stop-and-go or free-flow traffic. The virtual experience SP experiments were conducted by using a wraparound driving simulator. The two methods produced different results: the traditional computer-assisted SP data suggested that ramp delay is 1.6 to 1.7 times more onerous than delay on freeways, whereas the virtual experience SP data based on the driving simulator suggested that freeway delay is more onerous than ramp delay. Several factors are advanced to explain the differences, including recency, simultaneous versus sequential comparison, awareness of public opinion, intensity of the stop-and-go traffic, and the goal-directed nature of driving in the real world. However, without further research, it is unclear which, if any, of these factors will eventually prove to be the right one. What is clear is that a comparison of the computer-administered SP data with virtual experience SP data produces different results, even though both procedures strive to find the same answers in nominally identical sets of conditions. Because people experience the world subjectively and make decisions on the basis of those subjective experiences, future research should be aimed at better understanding the differences between these subjective methodologies.