Project: Roll Stability of Large Passenger Vehicles

Reference: S300A/VC

Last update: 11/12/2003 15:15:03


Proposed European legislation does not include the need for a tilt test. This project is to determine if tilt testing is necessary or if an analytical method represents a satisfactory alternative.


Bus and Coach safety represents a significant area of VSE interest. Although these vehicles represent the safest form of road passenger transport, any major bus or coach accidents, particularly those which involve rollover, can result in large numbers of casualties, and a considerable degree of public concern. Rollover accidents are relatively rare, but they account for a disproportionately high number of casualties. Studies have shown that while rollovers account for only 9% of recorded coach accidents, they cause over 40% of the fatalities and serious injuries. A reduction of rollover incidents could make a significant contribution to the Government's casualty reduction targets.

Since the 1920's, concerns over the possibility of rollover have been addressed by means of a static 'tilt test' which is currently a requirement in the UK Certificate of Initial Fitness, Equipment and use Regulations for PSV's. Single deckers are required to be tested to 35o and double deckers to 28o. This standard has probably been beneficial in minimising the number of rollover accidents in the UK, and it is likely to be used as the basis for a stability test to be included in new EU and UNECE bus type-approval legislation. However, due to the need for specialised equipment in order to perform the tilt test, there is some support within Europe for a calculation method to be used as an alternative to the UK's practical test. This research will establish whether such a method is capable of producing equivalent results to the practical test.


Anthony Best Dynamics
Holt Road, Bradford-on-Avon, Wiltshire, BA15 1AJ
+44 (0)1225 860200

Contract details

Cost to the Department: £163,430.00

Actual start date: 01 April 1994

Actual completion date: 31 December 1997


832. Tilt Behaviour of Large Passenger Vehicles: Practical and Calculation Methods. Final Report
Author: Anthony Best Dynamics Ltd
Publication date: 23/06/1997
Source: Contact:

Summary of results

  1. This research studied the tilt characteristics of buses and coaches and compared these with the current UK tilt test. The results of this study are fully detailed in the comprehensive final report.