Abstract
Research objective
The Euro NCAP protocol for pedestrian AEB system assessment only considers day-light conditions. Nearly half (48%) of all pedestrian fatalities within the EU‐23 states in 2008, however, occurred during night-time with low light conditions. Little information is available about night-time light conditions and the performance of pedestrian AEB system under these low light circumstances. This paper provides a method to reproduce typical measured night-time light conditions for performance assessment of pedestrian AEB systems under night-time light conditions in a reproducible way.
Methodology
To determine typical light conditions at which night-time accidents between passenger cars and pedestrians happen in Europe, the light conditions at blackspots are investigated. A blackspot is defined as a location at which a passenger car collides with a crossing pedestrian at night time. The typical night-time light conditions are reconstructed using white colored LED street lights in an indoor test facility to ensure reproducible test conditions for pedestrian AEB assessment tests. Pedestrian AEB systems of three passenger cars are assessed under day-time light conditions at an outdoor track as well as different levels of night-time light conditions, including fully dark, in TNO’s indoor test facility in Helmond, Netherlands. 14 near-side as well as 14 far-side pedestrian AEB tests are performed for each light condition with different vehicle speeds (20-50 km/h) using a static pedestrian dummy with white and black colored jacket that crosses the vehicle path with 5 km/h.
Results
The illuminance levels during night-time are measured at 20 different accident locations in the Netherlands and Germany. Both horizontal and vertical illuminance distributions over the pedestrian path are measured. From these measurements two well-defined night-time light conditions (low and average) are determined for near-side as well as far-side accidents. These well-defined night-time light conditions are successfully reconstructed in a reproducible way in the indoor test facility. For each car, a total of 112 pedestrian-AEB assessment tests are performed with light conditions varying from daylight to night-time in 4 levels: daylight, average street light, low street light and fully dark. The performance of pedestrian AEB systems under different light conditions are compared by measuring the speed reduction at collision and time to collision at braking and warning. Differences are found between the performance of the pedestrian AEB systems under different light conditions for the different cars.
Limitations of this study
The illuminance levels during night-time were measured at 20 locations in two countries in Europe. To determine typical illuminance levels for night-time pedestrian accident locations in Europa data from more locations in more countries is needed.
What does the paper offer that is new in the field in comparison to other works of the author?
This paper provides information about night-time light conditions (in Europe) for performance assessment of pedestrian AEB system under low-light circumstances. Conclusions The paper will show that the performance of pedestrian AEB systems depends on the light conditions, which should be taken into account in the assessment methodologies for pedestrian AEB systems.
Key Words : Pedestrians; Night-Time Light Conditions; AEB VRU Assessment