This note review some aspects of the problem of spray throw up by vehicles travelling at high speeds on wet roads. Reports of accidents on the M1 M10, and M45 were examined in order asses the degree to which spray could be considered as a cause of accidents on these motorways. It was found that 1.3. per cent of the wet weather accidents ( 1 in 245 of all accidents) which occurred on the main carriageways were attributed in the accident reports to vision being obscured by spray. To obtain some information on the factors affecticine-films have been made of both private and commercial vehicles travelling on wet roads. These films have shown these films have shown the spray to be of the kinds: water throw up directly by the wheel, and a fine mist-like spray which permeates the region of disturbed air around the vehicle. This fine spray is produced by a number of atomisation by high velocity air streams and by impaction of larger drops of water on the vehicles bodywork.Spray is caused by water throw up by the front wheels as well as the rear wheels. The quantity and distribution of spray is very dependent upon speed water depth and the vehicles aerodynamic characteristics. Flexible mud-flaps rear wheels do not appear to be particularly effective in reducing spray especially at high speed. Further investigations into the problem are in hand.
Samenvatting