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AURACLE ACOUSTICS  -  Road traffic

Road traffic noise

The central reference document in the UK for the monitoring and prediction of road traffic noise is the technical memorandum 'Calculation of Road Traffic Noise' (CRTN). This document was published by the Department of Transport in 1988 to provide a standardised approach to noise assessments undertaken in connection with the Noise Insulation Regulations 1975. The Noise Insulation Regulations were themselves introduced at that time to provide a standard means of delivering compensation to property owners whose properties were adversly affected (at or beyond the criteria specified in the Regulations) by noise from new or altered roads.

CRTN provides information on the monitoring of road traffic noise and its prediction from traffic flow counts or forecasts, taking account of factors such as percentage heavy vehicles, vehicle speed and road surface type and gradient.  It also includes a comprehensive series of noise prediction techniques which take account of the sound attentuation which can derive from propagation distance, reduced angles of view of the noise source, acoustic barriers and soft ground absorption.

The shortened noise monitoring procedure set out in CRTN requires that road traffic noise is monitored for a continuous period of three hours on a normal week-day between 10.00 hours and 17.00 hours at a location which is at least 4.0 metres from the nearest carriageway edge.  The 3-hour LA10 thus measured can then be converted to an 18-hour LA10 by subtracting 1 dB, and this figure is then readily converted to a 16-hour LAeq by subtracting a further 2 dB.

An 8-hour night-time noise level can be derived from a 16-hour LAeq figure by using a correction based on aveage hourly traffic flow figures provided in the 1999 DETR publication 'Transport Statistics Bulletin - Road Traffic Statistics 1999'.  The average hourly traffic flow figures in Table 3 of this document yield a day-time to night-time correction of -7.4 dB.  The 16-hour daytime and 8-hour night-time LAeq noise levels derived in this way may then be used for noise assessment undertaken in accordance with the requiremements of PPG24.

Auracle Acoustics is able to undertake all aspects of the monitoring, prediction and assessment of road traffic noise in accordance with national guidance such as CRTN, PPG24 and the specific requirements of local planning authorities, including the preparation of acoustic reports to support planning applications and liaison as required.

Information on the various means of controlling and mitigating against noise from sources such as road traffic may be found on the Noise Control page.


Copyright © 2003-2006 Owen Clingan - Auracle Acoustics


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