THE PREDICTION OF NOISE LEVELS FROM UNRESTRICTED TRAFFIC IN URBAN SITUATIONS BY MEANS OF A DIGITAL COMPUTER SIMULATION

A program has been developed which enables noise from road traffic to be simulated. This is achieved by using a digital computer to simulate the traffic behaviour at one-second intervals. At each interval the position, velocity and acceleration of every vehicle in the system is known. This enables empirically-derived functions which relate instantaneous sound pressure level from individual vehicles to velocity and acceleration to be incorporated. These functions allow instantaneous sound pressure level due to all the vehicles in the system at an observer position to be calculated. Hence the noise indices L10, L50, L90 and the increasingly applied leq can be derived over a simulated period. A series of 250 simulations has been carried out over a wide range of traffic parameters. The noise indices thus obtained have been related to the traffic parameters by the use of multiple regression techniques. This has enabled prediction equations for the noise indices to be derived.(a) (TRRL)