Yes / In the past it has been found that the maximum pass-by noise for the most noisy of vehicles can be 6-8 dB(A) above the average for the sample. It is therefore useful to consider the types of vehicle that make excessive noise and their condition and to reach some conclusions on how best to reduce the problem. Measurements of maximum noise, pass-by speed together with video footage were taken on a busy dual carriageway road (A34) in the UK carrying a high percentage of heavy vehicles. The intention was to collect sufficient information on light, medium heavy and heavy vehicles to enable typical characteristics of noisy vehicles to be identified. Peak noise levels produced by vehicles under normal operating conditions of steady speed were recorded and not of vehicle being driven in an aggressive manner e.g. under harsh acceleration. This paper reports on the characteristics of excessively noisy vehicles that were identified under these cruising conditions in free flow traffic conditions. / The work described in this report was carried out in the Noise and Vibration Team of TRL Limited under funding from the Transport Research Foundation.