Impacts of Luminosity in the Cab at Night on the Dynamic Distance of Visual Cognition

Suddenly encountering light sources at night will reduce drivers' dynamic distance of visual cognition. In order to investigate the law of quantitative changes of the visual recognition distance under the conditions of different speeds and different environmental luminosity around drivers, calibration experiments were conducted on an actual road. And on the basis of the data set from the experiments, using the method of curved surface regression analysis, the function models describing the rule of the visual recognition distance changing with the environmental luminosity around drivers and running speeds were established. The models were effective via statistical tests. Furthermore, combined with the automobile braking distance, the reaction time allowed for drivers and the critical speeds were analyzed then. Verification tests were also designed to test the established function model. Results showed that as the environmental luminosity around drivers increases, vision recognition distance decreases; as vehicle speed increases, vision recognition distance decreases. Therefore, the sudden showing-up light sources will affect the environmental luminosity in the cab and lead to the reduction in the visual recognition distance as well as the reaction time for drivers. In this circumstance, drivers must control the speed lower than the critical speed to avoid collision.