Prediction of L ₁₀ on Urban Main Roads

A simple and non-statistical theoretical method for predicting L ₁₀, tne sound level in dBA exceeded for 10 per cent of the time, due to traffic in urban main roads, is given here. L ₁₀ is determined as a function of the rates of flow of different types of vehicle for a given position of the observer (e.g. at kerbside or at 10m from the kerb). It is assumed that the traffic speed is generally uniform; this is consistent with vehicle behaviour on single carriageway urban roads subjected to a low speed limit (e. g. 48 km h⁻¹). Variations of speed and the effects of “bunching” are taken into account. The predictions of L _l0 compare well with experimental values obtained by STEPHENSON and VULKAN. It is also shown that, except where the density of heavy vehicles is low, L _l0 is determined solely by the presence of heavy traffic.