Analytical and experimental studies were done related to braking signals which indicate the level of deceleration, to allow selection of a limited set of such signalling concepts for evaluation of their effectiveness in reducing rear-end crashes in a field test. Literature reviews of prior simulator, driving and field tests were made, as well as accident data analyses. These tasks indicated that braking deceleration signals would have limited applicability, but one field test produced a large reduction in rear-end crashes. Potential means of coding rear lighting deceleration signals were developed, and subjectively evaluated in day and night driving. A study of flash rates showed that not more than three rates could be discriminated between 1 and 9 Hz, with an automotive bulb. Based on the foregoing tests a driving test was used to evaluate brake signalling displays, including deceleration signals, and a simulated brake signal failure. Measures related to car-following and rear-end collision performance were clearly degraded by the brake signal failure, and there were a few differences between the conventional and experimental configurations. Measurement of the braking deceleration distributions used by taxis and some motor-pool vehicles showed that taxis were a suitable fleet for the field testing phase of the study of braking deceleration signals, based on over 30,000 miles of exposure in both grous. Five configurations of braking signals were recommended for evaluation in a field test in their effects on rear-end crashes.
Abstract