Prepared for By

Project

Cranfield Airport Vehicle Testing and

Research Facility - Noise Assessment

Prepared for

Cranfield University

By

Lewis Bullivant BEng(Hons) AMIOA

Published

8 March 2021

Telephone +44(0)1787 247595 Website www.srltsl.com London, Birmingham, Manchester, Sudbury

SRL Technical Services Limited Registered office: Holbrook House, Little Waldingfield, Sudbury, Suffolk, CO10 0TF Registered in England No 907694

Quality Assurance

Project Title Cranfield Airport Vehicle Testing and Research

Facility

Document Title Noise Assessment

Client Cranfield University

Client Address

College Road

Cranfield

MK43 0AL

Author Lewis Bullivant BEng(Hons), AMIOA

Checker Jody Tan BEng(Hons) MIOA

Report Number 15653-SRL-RP-YA-001-S2-P3

Additional information -

Revision History

Revision Date Comments

P1 01/03/2021 Draft issue

P2 03/03/2021

Updated based on comments

from client. Changes by JYT and

checked by LB

P3 08/03/2021

Updated based on comments

from client. Changes by JYT and

checked by LB

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

Summary

SRL Technical Services Limited has been commissioned by Cranfield University to assess the noise impact

of the activities related to the proposed Vehicle Testing and Research Facility at Cranfield Airport.

The facility will be used by the Police Forensic Collision Investigation Network (FCIN), Highways England

and Cranfield University for testing and research. The facility will only be used during the daytime, typically

between 0800 to 1800 hours on Mondays to Fridays.

There are existing houses to the east (Townsend Close) south (High Street/Lodge Road/Swabley Lane) of

the proposed facility. The existing ambient noise around the site is dominated by activities relating to

Cranfield Airport (aircrafts landing and taking off) and the surrounding road network.

As the facility will only be used for testing and research, it is not expected to be used as frequently as a

commercial vehicle testing facility. I understand that the typical noisiest activity relating to the proposed

facility is noise from vehicles skidding on the tarmac during emergency braking. The vehicles will accelerate

up to approximately 40mph from the northern section of the facility before the driver will apply emergency

braking, causing the vehicle to skid at the southern section of the facility, away from the nearest houses on

Townsend Close. Other activities which will create significant noise at the proposed facility includes

aerodynamics and tyre tests where cars are driven up and down the tarmac at speeds typically up to

50mph. Vehicles crashing is also proposed but I understand that this is atypical of the proposed activities on

site and will be infrequent (up to 5 crashes a year).

I measured noise from typical vehicle activities at Cranfield University to replicate in my noise assessment

for the proposed facility. This included noise from a vehicle skidding on tarmac.

My assessment shows that the maximum noise levels (dB LAFmax) predicted at the nearby houses from cars

skidding at the facility is lower than the typical maximum noise levels from aircraft movements at Cranfield

Airport.

Noise from vehicles driving up and down the tarmac during aerodynamic and tyre tests is not expected to

cause any significant impact on the houses due to the nature of the tests (no skidding) and the existing

environmental noise at the houses.

I expect noise from vehicles skidding to be audible at the nearby houses but due to the existing noise levels,

frequency of skids and context of the site, noise generated from the proposed facility is not expected to

affect the amenity of the nearby residents where noise is concern.

As no data for vehicle crashing was available (and is not readily available) during the time of assessment, I

recommend SRL attend site on the day that the test is proposed to occur (on site or off site) to measure

noise from the activity. A secondary noise assessment must then be done to determine the impact on the

nearby noise sensitive receptors and if necessary, propose noise mitigation measures so that the maximum

noise levels (dB LAmax) does not exceed the existing levels.

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

Contents

Summary .................................................................................................................................................................................... 3

1.0 Introduction ................................................................................................................................................................ 5

2.0 Existing Conditions ................................................................................................................................................... 6

3.0 Assessment ............................................................................................................................................................... 11

Appendix A - Survey Details .............................................................................................................................................. 17

Appendix B - Measured Ambient Noise Levels ............................................................................................................. 18

Appendix C - Noise Measurement Parameter Definitions ......................................................................................... 22

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

1.0 Introduction

SRL Technical Services Limited has been commissioned by Cranfield University to assess the potential noise

impact of the proposed Vehicle Testing and Research Facility at Cranfield Airport for Cranfield University.

The facility will be used by the Police Forensic Collision Investigation Network (FCIN), Highways England

(HE) and Cranfield University for testing and research on vehicles stopping/skidding, aerodynamic tests and

for recreation of car crashes for investigation by the FCIN. The noisiest typical activity associated with the

proposed facility will be vehicles skidding on the tarmac.

There will also be some noise associated with vehicle movements on the tarmac, including HGVs and

forklift trucks during the recreation of crashes.

Vehicles crashing are proposed for the site, but I understand that this will be infrequent (up to 5 crashes a

year).

As the facility will be used for testing and research, it is not expected to be used as frequently as a

commercial vehicle testing facility. Figure 1 shows the layout of the test track and the location of the

nearest noise sensitive receptors (NSRs).

Figure 1 - Site layout in relation to noise sensitive receptors (NSRs)

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

2.0 Existing Conditions

2.1 Background noise levels

I attended the site on 23 February 2021 to measure the background noise levels at the nearest NSRs to the

proposed facility, the measurement location is shown below in figure 2. The microphone was fixed to a

tripod at least 1.5m above the ground and 3m from any other reflective surfaces. Table 1 shows the

measured noise level at the rear of the NSR on Townsend Close.

Figure 2 – Background measurement location used in 2021 noise survey

Table 1 - Background noise level at rear of NSR on Townsend Close

LAeq,5min (dB) LA90,5min (dB) LAFmax (dB)

53 45 72

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

Background noise measurements were dominated by distant road noise, some contraction noise to the

south-east and one small plane taking off from Cranfield Airport and flying overhead, which measured LAFmax

72dB.

Measurements were taken during the COVID-19 pandemic and at the time the governments advice was

such that "You must not leave, or be outside of your home except where necessary". It is expected that during

'normal' circumstances, noise from aircraft associated with Cranfield Airport will be the dominant noise

source at the NSRs, however due to the COVID-19, air traffic around the airport was low during our noise

survey. Therefore, I have supplemented our noise survey results with noise measurements taken at the site

by SRL in 2017 and publicly available online data measured by others in 2015.

2.2 SRL 2017 Noise survey results

SRL took measurements around Cranfield Airport, including measurements taken near to NSRs on

Townsend Close in 2017. The noise survey was done to inform the Environmental Statement for the

Cranfield Air Park hybrid planning application (LPA ref. CB/17/05862/OUT, granted 19 June 2019). Full

survey details are given in the SRL report 'T04/APP/61186A/RWB' dated 01 December 2017. The noise

survey measurement locations are shown below in Figure 3. A summary of the daytime noise

measurements results taken at position 'MP5' (circled in red), representative of NSRs on Townsend Close

are given in Table 2.

Figure 3 – 2017 Noise survey measurement locations

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

Table 2 - Noise survey measurement results taken in 2017 as location representative of NSRs on

Townsend Close

Date LAeq,T (dB) LAFmax (dB) LA90,T (dB)

Thursday 21/09/2017 51 80 39

Friday 22/09/2017 54 81 44

Saturday 23/09/2017 53 80 41

Sunday 24/09/2017 51 82 40

Monday 25/09/2017 47 75 38

Tuesday 26/09/2017 50 88 39

Wednesday 27/09/2017 52 80 42

Thursday 28/09/2017 56 85 44

Table 2 shows that daytime maximum noise levels at NSRs on Townsend Close are typically in the range

LAFmax 75-88dB and ambient noise levels are in the range LAeq 47-56dB.

2.2.1 Auracle Acoustics 2015 Noise survey results

Auracle Acoustics took noise measurements at a location representative of NSRs on High Street in 2015 to

support the planning application for the residential dwellings there (LPA ref. CB/13/04201/FULL, granted 05

March 2014). The location of this site is shown in Figure 4. Full survey details are given in the Auracle

Acoustics report 'Report-2015-08-12a', dated 12 August 2015. The measurement location is shown in

Figure 4. In summary, the highest maximum noise level of aircraft movements measured at a location

representative of NSRs on High street was LAFmax 74dB, a graph showing the noise level during the full

survey is shown in Figure 6. The report confirmed the maximum noise levels measured at the location was

mainly due to aircraft movements. Ambient noise levels were measured to be in the range LAeq,16h 48-50dB.

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

Figure 4: Aerial view of development with noise monitoring location shown as red dot

Figure 5 – 2015 Noise survey measurement location (extract from Auracle Acoustics report)

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

Figure 6 – 2015 Noise survey measurement result graph (extract from Auracle Acoustics report)

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

3.0 Assessment

3.1 Proposed operations

The facility will be used by Cranfield University, FCIN and Highways England. I understand that the typical

hours of operation are between 0800 to 1800 hours on Mondays to Fridays.

The proposed facility will be used for three types of test scenario.

• The first type of test is referred to as Method Validation test, in which cars are fitted with new types of tyres from different tyre manufacturers; the effect different road surfaces and weather conditions will also be investigated. The vehicles will be driven down the track at speeds of approximately 60mph before the driver hits the brakes to cause the car to skid at the southern portion of the facility. It is estimated that a maximum of 300 skids will be done over 5 days. In practice, this would typically mean that there can be up to approximately 40 skids a day for one or two days, before the vehicles are taken away for a few days to be serviced and new tyres fitted before the next batch of tests to be done. Each skid will last for approximately 3 to 5 seconds and will only be done during the daytime.

• The second type of test is referred to as Competency Testing. This is used for police training FCIN staff

in investigating accident scenes. Typically, skid marks will be created at a speed of up to 40mph before

the mock accident scene is created. This is done by placing vehicles around the area where the skid is

produced. It is expected that there will be approximately 48 skids done in an entire week. In the week

after the skids, FCIN staff will process their findings so no noisy activity will take place on site.

• The third type of test is referred to as Method Witnessing. The process of this test is similar to Competency Testing but will only take place four weeks in a year.

It is evident that majority of the activities for the proposed site will not be noisy. The noisy events are

relatively infrequent when compared to the dominant noise source within the area which is aeroplane

movements from the airport.

In addition to the tests by FCIN, Cranfield University will from time to time use the facility for aerodynamic

and tyre tests. In these tests, cars are driven up and down the track at speeds of up to 50mph. There will

not be any skidding during these tests and they are no different to a normal vehicle driving on a road.

In very rare occasions, FCIN may use the facility to do vehicle crash tests, if required by Highways England.

This type of test will only happen up to 5 times a year and is unlikely to take place before 2023.

3.2 Activity noise levels

As previously discussed, the typical noisiest activity related to the proposed facility will be vehicles

stopping/skidding during emergency braking. I attended site accompanied by a representative of Cranfield

University to measure noise from a vehicle skidding and some of the other proposed activities on 23

February 2021.

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

For all measurements, the microphone was fixed to a tripod at least 1.5m above the ground and 3m from

any other reflective surfaces. In some cases, multiple measurements were taken for each activity, in these

cases I have presented the representative noise level of the activity, summary results are below in Table 3

and given in full in Appendix B. All noise measurements were taken at approximately 2 meters from the

source, except where noted. Measurements were taken with the vehicle on an asphalt road which is

comparable to the road surface that will be laid at the new test track. Measurement duration for each

event varies and is shown in Appendix B.

Table 3 - Activity noise levels

Noise source LAeq (dB) LAFmax (dB) SEL (dB)

Land Rover driving past* 69 77 78

Land Rover accelerating* 72 79 80

Land Rover brake (skidding)* 95 102 101

Range Rover driving past* 69 77 77

Range Rover accelerating* 79 86 86

Range Rover brake (no skid)* 72 79 78

HGV passing 79 85 87

HGV accelerating 79 85 87

HGV idling 72 73 84

Forklift truck passing 80 84 89

Forklift truck turning, lifting and reverse

(no reverse alarm), measured at 5

meters from source

72 77 84

* vehicles travelling at 40-50mph.

3.3 Noise modelling

Using the measured activity noise levels presented in Table 3, I have produced a noise model of the

proposed site using CadnaA (3D noise modelling software). I have modelled two variants to assess the

noise levels associated with the two main activities at the proposed site, which are vehicle movements for

aerodynamics and tyre tests and cars skidding. Results are shown in Figures 7 & 8.

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

Figure 7 - Noise levels due to vehicles movements for aerodynamics and tyre tests at 1.5m receiver

height, dB LAeq,T

Noise levels are predicted to be LAeq 50-51dBA at NSRs on Townsend Close and 37-39dBA at NSRs on

High Street.

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

Figure 8 - Noise levels due to vehicle skidding at 1.5m receiver height, dB LAmax

Maximum noise levels are predicted to be 44-57dB LAmax at NSRs on Townsend Close and 59-62dB LAmax at

NSRs on High Street.

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

3.4 Assessment in context

The predicted noise from the typical activities related to the proposed vehicle testing and research facility

is significantly lower than noise from aircraft taking off and landing when assessed at the NSRs. Noise from

noisier activities on the proposed facility such as vehicles skidding and aerodynamic and tyre tests are likely

to be audible at the NSRs but is not expected to affect the amenity of the nearby residents based on the

existing noise climate and the frequency of the activities. Table 4 shows the comparison of noise levels.

Table 4 - Comparison of noise levels

Receptor

Measured

ambient noise

level, dB LAeq

Predicted

LAeq due to

vehicle

movements

for

aerodynamic

and tyre

tests, dB(A)

Measured due to

aircraft, dB LAFmax

Predicted due

to vehicle

skidding, dB

LAFmax

NSRs on Townsend

Close 47-56 54 88 57

NSRs on High Street 48-50 42 74 62

Table 4 shows that the predicted noise level at the NSRs due to the typical use of the vehicle testing and

research facility is lower than the measured dB LAeq and significantly lower than the measured LAFmax noise

levels due to aircraft and therefore the proposed testing is unlikely to cause a noise disturbance especially

with the low frequency of events compared to noise from aircraft movements. As the current noise levels

on site are already accepted by CBC, I expect the lower noise levels and the less frequent noise events

from the proposed facility will also be accepted.

It is worth noting that the predicted noise levels are external noise levels at the NSRs, when assessed

internally within the dwellings, the predicted noise levels are expected to be between 10-15 dB lower

(assuming partially open windows) and are unlikely to be significantly noticeable over the daily activities

within the dwellings and the existing environmental noise.

In addition to noise generated by the typical activities (vehicle movements for aerodynamic and tyre tests

and vehicles skidding) at the facility, FCIN may occasionally use the site for crash testing, if required by

Highways England (up to 5 times a year). We were unable to assess the impact of noise from vehicles

crashing as there are no noise data available to do the assessment due to the nature of the activity. I

understand that as this is an atypical activity at the proposed facility, the operators will communicate with

the local community by giving advance warning to nearby residents when the crashes will occur. If crash

testing is permitted at this facility, I recommend SRL attend site on the day that the test is proposed to

occur. Noise from a crash will be measured and assessed to the nearby noise sensitive receptors. If

required, noise mitigation measures can be recommended so that the maximum noise levels (dB LAmax)

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

from car crashes do not exceed the existing maximum noise levels at the noise sensitive receptors during

the proposed time of activity.

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Appendix A - Survey Details

A1. Location of Survey

Cranfield Airport

A2. Date & Time of Survey

10:00 - 13:30 23 February 2021

A3. Personnel Present During Survey

Lewis Bullivant (SRL)

Kim Blackburn (Cranfield University)

A4. Weather Conditions during Survey

Sunny, dry, high winds

A5. Instrumentation

Bruel & Kjaer - Noise Meter AT2

Description Location SRL No. Make Model Serial

Sound Level Meter

(AT2, Green) Altrincham 814 B&K 2250 2575775

Pre-amp Altrincham 814 B&K ZC0032 5843

Microphone Altrincham 814 B&K 4189 2573767

Calibrator Altrincham 815 B&K 4231 2575525

A6. Calibration Procedure

Before and after the survey the measurement apparatus was check calibrated to an accuracy of ±0.3 dB

using the type 4231 Sound Level Calibrator. The Calibrator produces a sound pressure level of 93.8 dB

re 2 x 10-5 Pa at a frequency of 1 kHz.

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

Appendix B - Measured Ambient Noise Levels

Measurement

Duration Activity LAeq LAFmax SEL

00:00:09 2m from road edge - Land Rover driving past 69 79 79




00:00:06 2m from road edge - Land Rover accelerating 72 79 80




00:00:04 2m from road edge - Land Rover skidding 89 98 95





00:00:26

plane flying overhead, measured near to parked car by test

track 59 67 73

00:00:04 2m from road edge - new Range Rover accelerating 72 79 78

00:00:23 plane flying overhead, measured next to test track 66 74 80

00:00:05 2m from road edge - new Range Rover driving past 69 76 76

00:00:06 2m from road edge - new Range Rover driving past 69 77 77


00:00:04

2m from road edge - new Range Rover braking (no skid)

72 79 78


00:00:06 2m from track edge - HGV passing by 79 85 87

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

Measurement

Duration Activity LAeq LAFmax SEL

00:00:06 2m from track edge - HGV passing by 78 82 86

00:00:06 2m from track edge - HGV accelerating 79 85 87

00:00:05 2m from track edge - HGV accelerating 79 85 86

00:00:16 HGV idling at 2m 72 73 84

00:00:08 Forklift passing by at 2m 80 84 89

00:00:16 Forklift turning, lifting and reversing at 5m 72 77 84

00:00:22 Forklift turning, lifting and reversing at 5m 71 77 85

00:05:09 Background at rear of NSR 53 72 77

LAFmax Octave Band Levels

Measurement

Duration Activity 63 125 250 500 1k 2k 4k dB(A)

00:00:09

2m from road edge -

Land Rover driving past 86 79 77 75 74 72 67 86

00:00:06

2m from road edge -


00:00:07

2m from road edge -


00:00:06

2m from road edge -


00:00:06

2m from road edge -

Land Rover accelerating 87 82 76 76 74 72 67 87

00:00:05

2m from road edge -


00:00:07

2m from road edge -


00:00:05

2m from road edge -


15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

Measurement


00:00:04

2m from road edge -

Land Rover skidding 84 76 72 92 97 85 75 84

00:00:04

2m from road edge -


00:00:05

2m from road edge -


00:00:04

2m from road edge -


00:00:04

2m from road edge -


00:00:26

plane flying overhead,

measured near to

parked car by test track 73 70 70 67 62 57 58 73

00:00:04

2m from road edge -

new Range Rover

accelerating 85 73 75 77 76 68 62 85

00:00:23


measured next to test

track 75 71 75 72 69 69 63 75

00:00:04

2m from road edge -

new Range Rover

accelerating 76 69 68 71 74 69 61 76

00:00:23


measured next to test

track 82 71 69 72 75 70 62 82

00:00:05

2m from road edge -

new Range Rover

driving past 70 76 81 82 81 77 73 70

00:00:06

2m from road edge -

new Range Rover

driving past 81 72 69 70 75 74 67 81

00:00:05

2m from road edge -

new Range Rover

accelerating 77 81 82 82 82 79 74 77

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

Measurement


00:00:04

2m from road edge -

new Range Rover

braking (no skid) 88 83 86 83 81 75 69 88

00:00:05

2m from road edge -

new Range Rover

accelerating 85 85 86 80 77 72 67 85

00:00:06

2m from track edge -

HGV passing by 90 87 87 83 80 76 69 90

00:00:06


HGV passing by 89 87 89 82 78 74 69 89

00:00:06


HGV accelerating 77 75 70 69 70 67 61 77

00:00:05


HGV accelerating 93 86 81 83 78 78 70 93

HGV idling at

2m HGV idling at 2m

85 81 75 76 71 72 65 85

Forklift passing

by at 2m Forklift passing by at 2m

86 81 77 72 71 73 64 86

Forklift turning,

lifting and

reversing at 5m

Forklift turning, lifting

and reversing at 5m 84 74 76 73 64 57 55 84

Forklift turning,

lifting and

reversing at 5m

Forklift turning, lifting

and reversing at 5m 86 79 77 75 74 72 67 86

Background at

rear of NSR

Background at rear of

NSR 81 77 76 74 72 70 65 81

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

Appendix C - Noise Measurement Parameter Definitions

LAmax - The “A” weighted maximum noise level measured during the stated measurement period.

LAeq - The "A" weighted equivalent continuous sound pressure level. A representation of a continuous

sound level containing the same amount of sound energy as the measured varying noise, over the

measurement period. It can be considered as the "average" noise level.

15653-SRL-RP-YA-001-S2-P3 08/03/2021 of 23

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