The European Regulations introduced over the last years on the enhancement of secondary safety of buses and coaches are proving to be efficient, reducing accident seriousness and their consequences, as real accident data can show. However these measures seem to be insufficient, especially in certain impact configurations such as frontal collisions in which not only the driver and the crew are the most prone to casualty but also the rest of the occupants who often suffer severe or fatal injuries.
The aim of the study presented in this paper is to identify the main characteristics of large passenger vehicles (LPVs) frontal collisions that have occurred in Spain over the last years, and to analyse the compatibility of these vehicles with their collision partners or obstacles in frontal impacts.
The study has two main parts: a statistical analysis based on the Spanish Accident Database that includes bus accidents occurred in Spain between 1993 and 2008 investigated by the Police Forces with at least one injured person as consequence of the accident; and an in-depth study using a LPV accident database including highly detailed information, retrospective investigation, reconstruction, police reports and medical records with injury description and mechanisms. A total of 28 real-world accidents were considered, in depthanalysed by the Accident Research Unit of INSIA and investigated in collaboration with the Police Forces, Paramedics and Hospitals.
It is expected that the results obtained in this research will help to gauge the extent of the problem in the Spanish roads and to understand the influence of compatibility on the injury severity of the occupants of both vehicles and their mechanisms.
The statistical analysis revealed that interurban frontal bus accidents represent around 50% of the total Spanish interurban bus accidents with killed or severe injuries. The in-depth analysis based on the injury mechanisms most commonly found suggests that new structural solutions in the frontal design of the bus should be considered to enhance occupant protection and to improve the compatibility between the vehicles involved.
There are not many research works about LPVs frontal collisions up to day, so the potential enhancement of secondary safety is still high. This study is based on Spanish data and its conclusions reflect the situation in the Spanish roads, however it should be extended and considered as guidelines for future research works.