Abstract
In Japan, 70% of fatal accidents involving pedestrians occur while the pedestrian is crossing a road, and 70% of these accidents occur at nighttime. Although nighttime crossing accidents occur under various lighting environments, the relevant data has yet to be analyzed systematically. In contrast, nighttime illuminance conditions are a very important element in performance assessments of pedestrian pre-crash safety systems (PCS). Therefore, this research investigated the illuminance conditions of fatal nighttime crossing pedestrian accident sites following the walking locus of the pedestrian to calculate the illuminance distribution at the site. Based on the results of the analysis, this paper describes nighttime illuminance conditions for pedestrian PCS assessment and a method to reproduce these conditions.
This research selected Tokyo as the investigation location since fatal pedestrian accidents are common (Tokyo generally has the highest or second highest number of fatal pedestrian accidents in Japan) and because the available accident data includes the loci of the vehicles and pedestrians involved. In the investigation, all 76 fatal pedestrian accidents that occurred between May 2012 and May 2013 were analyzed and confirmed to be representative data for Japan. From these 76 incidents, this research then extracted all 35 accident sites at which a vehicle going straight on collided with a crossing pedestrian at nighttime. The nighttime illuminance conditions were analyzed following the locus of the crossing pedestrian to identify the horizontal and vertical illuminance distributions. The cumulative illuminance distribution was calculated at the collision point between the vehicle and pedestrian, and for one-meter intervals from that point.
The cumulative illuminance probability of 0.2, 0.5 and 0.8 was showed. For example, the nighttime illuminance conditions for horizontal illuminance are as follows, respectively. In the case of accidents involving pedestrians crossing from the left (i.e., the near side), each illuminance at the collision point is 6.9 lx / 15.3 lx / 29.0 lx. In the case of accidents involving pedestrians crossing from the right (i.e., the far side), each illuminance at the collision point is 4.7 lx / 15.2 lx / 32.0 lx.
KEYWORDS – illuminance, nighttime, pedestrian, crossing, pre-crash safety system