Abstract
The conclusions drawn from accident statistics are the basic tools in the improvement of road safety including vehicle safety. The paper discusses some theoretical ideas being important in collecting, analysing and comparing accident statistics: statistical sample, sample size, limit of validity, generality/peculiarity. The sample may depend on the bus categories being involved (city bus, tourist coach, double deck bus, small bus, etc.), or on the type of the accident (rollover, frontal collision, fire, etc.) and the casualties (injured in the accident, fatality in the accident, casualty on board, etc.) The relation between accident statistics and the in-depth accident analysis is also discussed. The more precise grouping of accidents into a statistical sample, the more reliable, comparable and more effective conclusions. The paper shows a new way to collect bus accident information: to collect the media information, reports. The bus accidents generally are very “spectacular”, “shocking”, therefore the media is very sensitive for these events. The paper presents the accident statistics of buses collected by the author containing information about more than 1000 bus accidents. The major accident types are analysed on the basis of the statistics: rollover, frontal collisions, fires, collision with trains and to compare them in respect of their severity using the concept of casualty rate. The casualty rate is the average number of casualties in one accident related to a statistical sample. This is a good parameter to characterize the severity of different accident situations. The paper shows the major injury mechanism in rollover and frontal collision of buses. The bus fire is a two-faced accident type in respect of the casualty rate, as the paper shows. The paper clearly points out that to improve the road safety – based on accident statistics – is a completely different task as to improve the vehicle safety, e.g. to improve the occupant safety of buses in rollover. The accident statistics could be a very useful tool to check the effectiveness of safety orders, provisions (e.g. introducing new international safety regulation). As an example, UN-ECE Reg.66 is examined. The bus rollover statistics, as a direct and indirect feedback is studied that requirements of R.66 are really effective, good enough to improve significantly the occupants safety in rollover. The bus accidents are rather rare compared to other vehicle categories; this is due to the small number of buses in the total road vehicle fleet. Therefore every available bus accident statistics is useful and welcomed. The collected accident information – as a large database – may be used not only for statistical evaluations, but also for in depth analysis of different accident situations. As an example, the usability of different emergency exits of buses in different accident situations are shown and briefly analysed. The very high injury probability of the drivers in frontal collisions is also proved by the statistical data. Finally, as conclusions, the paper gives some advices how to collect, evaluate and use bus accident statistics in the safety improvement process of buses.