Pedestrian Safety Margins Under Different Types of Headlamp Illumination

Several previous studies have been performed to evaluate the performance of vehicle headlamps with new technologies (e.g., high-intensity discharge, light-emitting diode, and adaptive forward lighting systems). Most of these studies have provided empirical evidence suggesting the promise of these newer technologies for improving roadway safety by improving visual performance of drivers. Recent efforts to develop predictive tools for characterizing headlamp performance have resulted in mathematical models to predict response times to potential hazardous objects varying in reflectance, size, angular position, and distance, as a function of the intensity and spectral characteristics of the light reaching such objects. These mathematical models can provide precise estimates of visual performance under quite controlled conditions not necessarily representative of those experienced by drivers in real-world conditions. The present report describes the results of a field study using different types of headlamp illumination (e.g., halogen and high-intensity discharge) for the detection and recognition of roadside pedestrian targets. The relative ability of drivers to stop in time when they detect pedestrians about to enter the roadway (as opposed to pedestrians about to exit the roadway) is presented. The correlation of these results to the mathematical response time models allows the results of calculations using such models to be transferable to more realistic, safety-relevant situations.