Projects

Example Reports

SAMPLE NOISE MEASUREMENTS ...

Scope of Report

To factually present noise measurements made at an existing and a proposed site of. ...

1. INTRODUCTION

1.1 The ... intend to develop a vacant site at ..., for motor-trades use.

1.2 The local authority has requested that noise measurements of sample activities that are likely to occur be made.

1.3 Civil Engineering Dynamics were instructed by the .... to undertake noise measurements of sample activities at their existing works at ..., and also measurements of the existing background noise at the proposed site.

2. THE SITE

2.1 An indicative plan of the site at is shown in Figure 1.

2.2 ... Road is a busy main road and bus route. 'Gridlock' frequently occurs at peak hours.

2.3 The proposed development would involve a line of single storey workshops facing east. An indicative outline is shown in Figure 1.

2.4 The residence that bounds the site to the east (in ... Road) is expected to be most affected by noise from the workshops. The western wall of the house is approximately 9m distant from the eastern face of the workshops. There are no windows in the western wall of the house, although some windows on the south façade are bays.

3. MEASUREMENT PROCEDURE

3.1 All measurements were made using a Bruel & Kjaer 2260 Investigator Type 1 Sound Level Meter.

3.2 Measurements were made on 2nd February 01. The weather was dry with little wind.

3.3 Measurement locations are shown in Figure 1.

3.4 Three one-minute noise samples were made at the ... Road entrance to the site, approximately 10m from the nearside carriageway edge (location 1).

3.5 Three one-minute samples were made at the south-eastern corner of the site, near to the house (location 2). The wall surrounding the site is approximately 1.8m at this point.

3.6 Sample measurements were made of the following activities occurring at the ... Road site:

  • Air gun removing wheel nuts
  • Radio (general measurement in room - not 1m from radio)
  • Ramp raising and lowering car.
  • Spanner being dropped on workshop floor.
  • Engine Idling
  • Roller shutters raise / lower.

3.7 All measurements were made at approximately 1m to reduce the effects of reverberation specific to the ... Road site (the proposed building is to be lower and less reverberant) and to reduce contamination from background noise.

3.8 The measurement duration varied depending upon the source. Where an impulsive noise was in question, the noise sample includes a number of repetitions of the noise.

4. RESULTS

4.1 The results of the background noise measurements made at are shown in Table A.

Table A: Background Noise Measurements

Meas. Loc. Start Time LAeq,1min (dBA) LAmax,s (dBA) LAF90 (dBA)
1. 11:42
71.0
79.1
63.6
11:45
70.1
75.6
62.2
11:46
71.0
77.9
64.6
2. 11:50
58.4
61.4
54.6
11:51
58.6
66.4
50.8
11:52
56.9
61.5
48.8

4.2 The results of the sample measurements made at ... Road are shown in Table B.

4.3 The parameters used are those considered to be the most useful to categorise the sound in question. LAmax,S (maximum sound pressure level occurring) is used for impulsive sounds such as bangs and clatters. LAeq,T (equivalent continuous sound pressure level) for continuous or random sources such as the car idling.

4.4 An estimate of the possible noise levels present at the windows of the house adjoining Road is shown in Table B.

4.5 The levels are corrected for the range of distances that may occur. The distance correction takes into account the spectral content of the source as high frequencies decay over a shorter distance that lower frequencies.

4.6 It is difficult to estimate the reduction that will occur due to the partially open enclosure of the workshops. PPG24 'Planning and Noise' suggests that an open window provides 10 - 15 dB reduction. Sample measurements of the spanner drop made outside the workshops, although contaminated to a degree by background noise, showed a decay of over 20 dB over a distance of about 15m. Assuming that 6 dB/doubled distance is a reasonable distance correction for a high frequency transient such as a spanner drop, 5 dB may be a reasonable correction to apply for an open double door.

TABLE B: Sample Measurements

Source Meas. Time (s) LAeq,T (dBA) LAmax,S (dBA) Range of Distances (m) Range of estimated distance correction (dB) Estimated SPL at window
LAeq,T (dBA) LAmax,S (dBA)
Air Gun
21
90.7
9 - 25
15 – 20
-
65 - 70
Radio
11
60.2
62.0
10 – 15
40 - 45
Ramp
30
74.3
82.9
15 – 20
49 - 54
63 - 68
Spanner
11
99.5
20 – 30
-
65 - 75
Engine
11
65.5
66.1
10 – 15
45 - 50
Roller Shutters
14
64.8
67.5
10 – 15
45 - 50