Evaluation of Short-Range Roadway Delineation

A distinction is drawn between long- and short-range delineation, the latter being provided to aid the driver in tracking the roadway at night and under poor visibility conditions. A quasi-linear describing function approach is employed to represent the driver as a sensor and controller, and it is hypothesized that reductions in the quality of the driver's visual field will be reflected by an increase in the level of the “remnant” (interpreted in part as visual observation noise). Experiments were performed on a rural road, to which a variety of delineation treatments were applied, using a vehicle that permitted the identification of driver-vehicle describing functions as subjects negotiated the test course. The results are generally supportive of the experimental hypothesis, with the describing function parameters yielding evaluations of delineation treatments that are consistent with each other and with subjective ratings of task difficulty.