Written question asked by Lord Arbuthnot of Edrom (Conservative) on Thursday, 21 June 2007, in the House of Commons. It was due for an answer on Monday, 25 June 2007. It was answered by Stephen Ladyman (Labour) on Monday, 25 June 2007 on behalf of the Department for Transport.

Lorries: Noise

Question: To ask the Secretary of State for Transport if he will estimate the change in noise level adjacent to an (a) A class road and (b) motorway arising from an additional traffic volume per day of (i) 400, (ii) 600, (iii) 800 and (iv) 1,000 heavy goods vehicle movements.

Answer: The method used in the UK for calculating road traffic noise requires a baseline volume of traffic. The change in road traffic noise, including from heavy goods vehicles (HGVs), is calculated from the change in the baseline traffic level. A change in traffic noise level cannot be calculated with only absolute increases in traffic volumes.If all the other factors that influence road traffic noise remained unchanged, a 10 per cent. change in HGVs is approximately equivalent to a one decibel noise change.

Secondary information