§ Mr. Geoffrey Finsbergasked the Secretary of State for the Environment what studies he is undertaking on the extent and effect of noise in the vicinity of urban motorways; and if he will make a statement.
§ Mr. Peter WalkerStudies have been made by the Noise Advisory Council; others are being carried out as part of my Department's programme of practical research.
345WThe Noise Advisory Council has recently recommended to me the adoption of the "L10" index for measuring disturbance by traffic noise.* It has also recommended that existing residential development should in no circumstances be subjected, as an act of conscious public policy, to more than 70 dB(A) on the L10 index unless some form of remedial or compensatory action is taken by the responsible authority. The Council has stressed that this level represents, in its view, the limit of the acceptable rather than a standard of what is desirable and has recommended that wherever possible planners should design to lower levels.
I have undertaken to arrange for these recommendations to be taken into account in the future work of the Urban Motorways Committee, in the Government's review of compensation, and in considering possible further guidance to local planning authorities.
* The L10 is the noise level in decibels (dB(A)) which is exceeded for 10 per cent. of the time. Studies have shown that, measured outside houses over the period 6 a.m. to midnight, it correlates well with human reactions to motorway noise.