For mobile items of plant that pass at intervals (such as earth-moving machinery passing along a regular, well-defined route such as a haul road), it is possible to predict an equivalent continuous sound level using the following method:
`L_(eq,T) = L_W -33 + 10log_10(Q) - 10log_10(V) - 10log_10(d) + C`where:
`L_W` is the sound power level of the plant, in dB
`Q` is the number of vehicles per hour
`V` is the average vehicle speed in km/h
`d` is the distance from the centre of the haul road to the receiver position in m
`C` is 3 dB for plant items with twin engines, 0 dB otherwise
References:
BS 5228-1:2009, Code of practice for noise and vibration control on construction and open sites, Part 1: Noise, eqn F.6