Project: Paralellepipoid Noise Measurement Project
Acoustical Assessment
Client: Construction Contractor - Joint Venture
Location: China
Type of Project: Acoustic Assessment and Noise Measurement
Start: 2004

A major Joint Venture consortium of contractors engaged the services of Dr. David Green, of as an Accredited Monitoring Professional to determine sound power levels (SWL) for various powered mechanical equipment (PME) and prepare a noise assessment report. The use of SWL measurements provided business value and were used to advantage in the application for construction noise permits for a major drainage construction works contract.

The commencement of several related contracts had successfully brought the sewerage improvement works for the city forward into the construction phase. Advanced site preparation work started in February 2004 and construction commenced accordingly. Several sites were begun simultaneously to undertake tunnel construction works using trench less technology. Works were being carried out between the hours of 07.00hrs and 19.00hrs but not on Sundays or public holidays. However, in order to improve the progress of the works and therefore reduce the overall programme and duration of disturbance it was proposed that works could be extended from 19.00hrs to 23.00hrs or perhaps even overnight.

The objective of the noise measurements was to provide sound power levels (SWL) for several PME used routinely in the suite of trench-less technology plant and to advise on how to reduce the SWL from the individual PME by adding acoustic insulation where practicable.

This provided business value for the contractor and was necessary since the suite of PME used in trench-less works contains several pieces of equipment (de-sander etc.) not included on the list of typical sound power levels for PME published by the noise authority. Based on observation, some of the other typical construction PME used by the contractors was quite new and well maintained and had SWL much lower than the published sound power levels used for calculations under local statutory procedures.

The measurement site was selected to provide an uncomplicated environment to meet the normative qualifications for the acoustic environment set in Annex A to the BS EN ISO 3746:1966. No major items of plant or engines were near the PME being measured. The site was adjacent to a busy main road but there was not heavy traffic flowing during any of the measurement periods.

Noise measurement positions

The SWL for all major items of PME in the trench-less technology suite and some other typical plant were measured. Noise measurement followed the British and European Standard BS EN ISO 3746:1966 (Acoustics - Determination of Sound Power Levels of Noise Sources using sound pressure – Survey method using and enveloping surface over a reflecting plane).

Background monitoring of noise was undertaken with the PME switched off immediately prior to noise measurements, intermittently during noise measurements and immediately after noise measurements. Background levels were in all cases >10dB (A) lower than the measured noise at the microphone positions therefore no background correction was applied. The weather conditions and noise sources were recorded before and during monitoring. An anemometer was used to check wind speed during the noise measurements. The measurement site is fairly well sheltered and wind conditions on all occasions were still.
Sound Level Meter: O1dB SIP95 (MVI technologies group) Serial No. 988124
Acoustic Calibrator: O1dB type Cal 1 IEC 942:1988   Serial No.108800
The monitoring professional calibrated the equipment prior to use. The measurement surfaces and microphone positions from the reference box were on the parallelepiped surfaces in strict compliance line with BS EN ISO 3746:1996.

Business value could be derived since some of the PME were unusual items of equipment for which the local noise enforcement authority had no standard SWL. Others were items of equipment which ran with SWL much lower than the standard SWL generally accepted by the local noise authority. The measurements could therefore be used for applications for construction noise permits and to determine if suites of equipment could be operated at certain times (e.g. 19.00hrs to 23.00hrs or later) in compliance with regulatory requirements. Business value for the contractor and benefits to the project accrued through greater flexibility in operating times, more optimal use of resources and the advancement of the contract programme.

Further advice was provided on how to modify the plant and include additional acoustic insulation, especially around the noisier elements of the plant, in order to reduce further the noise impact and provide additional business value.
could be derived since some of the PME were unusual items of equipment for which the local noise enforcement authority had no standard SWL. Others were items of equipment which ran with SWL much lower than the standard SWL generally accepted by the local noise authority. The measurements could therefore be used for applications for construction noise permits and to determine if suites of equipment could be operated at certain times (e.g. 19.00hrs to 23.00hrs or later) in compliance with regulatory requirements. Business value for the contractor and benefits to the project accrued through greater flexibility in operating times, more optimal use of resources and the advancement of the contract programme.

Further advice was provided on how to modify the plant and include additional acoustic insulation, especially around the noisier elements of the plant, in order to reduce further the noise impact and provide additional business value.

Locations for additional acoustic insulation