Hiroshima University evaluates advanced emergency braking systems for large trucks: No significant differences in collision rate and damage amount

On October 2, a research group led by Professor Toshiaki Shiomi (currently visiting professor at the School of Medicine), Associate Professor Hajime Kumagai (currently hospital clinical associate professor), and Researcher Kengo Kawaguchi (at the time of the study) of the Department of Sleep Medicine, Graduate School of Biomedical and Health Sciences at Hiroshima University, has announced their research results showing that the effectiveness of advanced emergency braking systems (AEBSs) is limited in terms of the collision rate and damage amount evaluated in drowsy driving-related real-world large truck collisions. Of the 563 collisions in which the damage amount was determined, 123 were related to drowsy driving (drowsy driving group), and there were no significant differences in the collision rate and damage amount between trucks with and without AEBS. The results highlighted the need for further improvement of AEBS and the establishment of methods for early detection of drowsiness for truck drivers. The work was published in the online version of the international journal SLEEP on August 22.

In April of this year, working hour regulations for truck drivers were introduced. To compensate for the labor shortage caused by these regulations, the speed limit for large trucks on highways was increased to 90 kilometers per hour. About 200 fatal truck accidents occur annually, although the number is declining. In Japan, AEBS equipment for large trucks has become mandatory for those manufactured after November 2018, and large trucks equipped with AEBS are becoming more common. Meanwhile, it was unclear to what extent AEBS was effective in preventing accidents.

The research group operated the Department of Sleep Medicine from 2009 until the end of March 2024, with a donation from Fukuyama Transporting Co., Ltd. They studied methods of preventing drowsy driving-related accidents involving occupational drivers. In April of last year, the research group revealed that drowsy driving-related accidents by truck drivers were attributed to short sleep for less than 15 seconds (microsleep).

In this study, they evaluated the effectiveness of AEBS on drowsy driving-related collisions involving large trucks. The evaluation employed collision rate (number of trucks with collisions/total number of trucks) and damage amount (total amount of property damage and personal injury) as measures based on real-world data on drowsy driving-related large truck collisions. The involvement of drowsy driving was determined based on drivers' self-reporting and dashcam video footage.

Specifically, of 1,699 collisions that involved large trucks of Company A and occurred between April 2016 and March 2023, 618 were on-road collisions. Among these on-road collisions, 563 collisions for which the collision damage amount was determined were included in the analysis. Large trucks were defined as those with a gross vehicle weight of 11 tons or more, including 12,887 with AEBS and 18,220 without AEBS. Of the aforementioned 563 collisions, 21.8% and 78.2% were accounted for by collisions related to drowsy driving and those not related to drowsy driving (non-drowsy driving-related collisions), respectively. Collisions involving trucks with AEBS accounted for 37.1%, while those involving trucks without AEBS accounted for 62.9%. The analysis in all collisions showed that the collision rate for trucks with AEBS was significantly lower than that for trucks without AEBS. However, the analysis in drowsy driving-related collisions showed that the collision rate did not significantly differ between trucks with and without AEBS. The comparison of the damage amount shows that no significant differences in either case.

When collision rates among trucks with the first, second, and third generation AEBS were compared, the rates of non-drowsy driving-related collisions decreased for trucks with newer generation AEBS, but the rates of drowsy driving-related collisions did not differ significantly among generations.

Shiomi said, "Accidents cannot be prevented by the vehicle function once the truck drivers have fallen asleep, and I think the vehicles are stopped by the drivers using their skills. Truck development seems stagnant and needs more improvement. I believe that this result also has medical significance in our quest to ensure safety, transport quickly, and achieve what we call 'zero traffic casualties.'"

Journal Information
Publication: Sleep
Title: Evaluation of advanced emergency braking systems in drowsy driving-related real-world truck collisions
DOI: 10.1093/sleep/zsae196