Annex a - Dossier on Noise and Vibration

7/28/2019 Annex a - Dossier on Noise and Vibration

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Annex A - Lambeth Residents concerns on NLE noise impacts

This dossier sets out the ongoing concerns which residents feel about theproposals as set out in the current TWAO application and accompanyingEnvironmental Statement, and in particular on the issue of noise and

vibration, which are likely to be the single biggest source of nuisance andhealth impacts on local residents.For the majority of Lambeth residents on the NLE route, the issue ofoperational noise will be the principal ongoing impact, and this group hasreceived a great deal of correspondence on the possible effects on healthof low rumblings every couple of minutes, from 05h30 till 01h00, 364 daysa year (and potentially further into the night at weekends, if TfL decides toadopt later running). This will be accompanied by periodic vibrations,which when combined with noise could have the effect of damaginghealth and property.Much greater impacts will also be felt in the concentrated period duringconstruction, when noise levels close to the main works sites could be sosignificant as to require remedial actions including potentially evacuatingparticularly-affected people.

Methodological issuesThere are a number of different scientific techniques to measure noiselevels, of which the most important in this context is dB L(A)max. Acomparison between these techniques can be found in the Appendix atthe end of this paper. This supports our and TfLs view (in theEnvironmental Statement) that the most stringent test, dB L(A)max,fast , is

the appropriate measurement for comparing the effects of the NorthernLine Extension with other relevant projects and standards.

Health implications of operational noiseNoise arises from many different types of sources and activities. Thesimple definition of noise is that it is unwanted sound, and as such, mayhave both direct physical and psychological effects on people if it isintense or persistent enough; causing sleep disturbance, interfering withnormal conversations, or annoyance and stress. Evidence is accumulatingthat noise has real health effects on people and can be particularlydamaging to normal human behaviour: it can interfere with complex task

performance, modify social behaviour and cause annoyance, and thattransport noise in particular, with its peaks and troughs in intensity isassociated with psychological symptoms and with the use of psychotropicmedication1 .A number of studies have been carried out over the years whichdemonstrate the clear linkages between ongoing noise and detrimentalhealth2

1Stephen Stansfield, Mary Haines & Bernadette Brown, Noise and Health in the Urban

Environment, Reviews on Environmental Health (vol 15, no.1, 2000)

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Annoyance: The World Health Organisation3 noted that annoyanceresponses in individuals are not just conditioned by acoustic factors suchas noise source, exposure level and time of day exposure, but also non-acoustic al factors such as the extent of interference experienced, abilityto cope, expectations, fear associated with the noise source and beliefs

about whether those responsible for causing the noise could also reduceit.Hyper-tension and coronary heart disease: a meta-analysis found that foraircraft noise, a 5dBA rise in noise was associated with a 25% increase inthe risk of hypertension compared with those not exposed to noise.4

Sleep disturbance: a recent synthesis of field studies concluded that therewas sufficient evidence that night-time noise exposure was causing directbiological responses, at approximately 40dB, as well as affecting well-being and quality of sleep.5

Railway noise has generally been considered as the least annoyingtransportation source, and, therefore, it has not achieved the sameattention as road traffic and airport noise. However, recent studiessuggest that nocturnal railway noise is as disturbing to sleep as roadtraffic noise6 and that railway noise has important short-term impact onthe cardiovascular system and might increase the risk for hypertension.Underground railways do mitigate some of the pure decibel intensity ofstandard noise pollution caused by rail and in particular the often shrillfrequency of this noise. However, groundborne noise brings subtlydifferent challenges, in that it cannot be mitigated by the standardapproaches used for airborne noise, such as double-glazing. Other recentstudies demonstrate that where there are ground-borne noise and

vibration, significantly lower noise levels are needed in order to generateannoyance and the associated ill-health effects.7 In Norway, therequirement for structure-borne noise from tunnels is no higher than 32

Stephen Stansfield & Charlotte Clark, The Effect of Transportation Noise on Health andCognitive Development: A Review of Recent Evidence, International Journal of ComparativePsychology (vol 20, pp.145-158, 2007)

3World Health Organisation, Guidelines for Community Noise, 2000

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E. van Kempen et al, The Association between noise exposure and blood pressure andischemic heart disease: a meta-analysis, Environmental Health Perspectives (issue 110,3, pp.307-317, 2002)

5HCN, The influence of night time noise on sleep and health, Health Council of the

Netherlands publication 2004/1E, 2004

6P Lercher et al, The effects of railway noise on sleep medication intake: results from the

ALPNAP-study, Noise Health (2010, 12:110-119) and J Hong et al The effects of long-term exposureto railway and road traffic noise on subjective sleep disturbance , Journal of the Acoustic Society of

America (2010, 128:2829-2835)

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dB L(A)max, fast inside dwellings, and yet this level of noise has been shownto cause annoyance to 20% of the exposed population.8

Relevant international standards for noise levels which causehealth disturbance

The World Health Organisation9 set out in 2009 a list of what it consideredto be the threshold noise levels which would have health impacts onindividuals, and its list is the following:Biological/health issue Noise threshold10

Motility, onset of motility 32 dB L(A)max, insideEEG awakening 35 dB L(A)max, insideChanges in sleep structure 35 dB L(A)max, insideWaking up in the night 42 dB L(A)max, insideIncreased use of sedatives andsomnifacient drugs

40 dB (L)night, outside

Self-reported sleep disturbance 42 dB (L)night, outsideOnset of hypertension 50 dB (L)night, outside

On the basis of the above effects, the World Health Organisationsuggested that night noise above 40 dB(L)night, outside would bepositively damaging to health, while recognising that vulnerableindividuals (for example children, the chronically ill and the elderly) wouldbe susceptible to health impacts given noise levels in the 30-40 dB(L)night, outside range

It should be noted that the WHOs guidelines on night noise are expressedin terms of decibels encountered at night, and that this measure assumesthat for part of the year, bedroom windows will be open for the purposesof ventilation. Rupert Thornley-Taylor, who is incidentally the noiseconsultant engaged by TfL for the Northern Line Extension, explained to agroup of Lambeth residents in January 2013 that to make the these WHOnight noise guidelines meaningful, this figure needs to be converted into afigure for noise encountered inside a bedroom, which he stated would beapproximately 25 dB L(A)eq, 8hr.

Anita Gidlf-Gunnarsson et al, Railway noise annoyance and the importance of number oftrains, ground vibration, and building situational factors , Noise and Health, (vol14, issue 59, 2012)

8Gunn Marit Aasvang et al,Annoyance and self-reported sleep disturbances due to

structurally radiated noise from railway tunnels, Applied Acoustics (vol 68, Issue 9, Sep 2007, Pages970981)

http://www.sciencedirect.com/science/article/pii/S0003682X06000892

9World Health Organisation, Night Noise Guidelines for Europe, (WHO Regional Office for

Europe, 2009)http://www.euro.who.int/__data/assets/pdf_file/0017/43316/E92845.pdf

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N.B. WHO did not make clear whether these figures are quoted as dB L(A) max,fast ordB L(A)max,slow
http://www.sciencedirect.com/science/article/pii/S0003682X06000892http://www.euro.who.int/__data/assets/pdf_file/0017/43316/E92845.pdfhttp://www.sciencedirect.com/science/article/pii/S0003682X06000892http://www.euro.who.int/__data/assets/pdf_file/0017/43316/E92845.pdf


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Given the long average of this 8-hour figure which is not equivalent tothe peak noises that could be expected from a railway it is safer andbetter to use the dB L(A) max, inside figures quoted by the WHO in their reporton when peak noise can cause biological effects on sleep patterns.In this case, as quoted above, WHO believes that noise levels of 32 dB

L(A) max, inside can cause the onset of motility, and so it is safer for TfL andother designers of underground railways to ensure that their systems to abetter standard than this. As has previously been noted, this is alreadythe maximum level of ground-borne noise permitted from new tunnels inNorway.

British Standards for operational noiseCurrently no British Standards exist which recommend a method by whichto assess intermittent ground-borne or structure-borne noise, such as thatinduced by trains.TfLs Environmental Statement also makes reference to levels of adversereaction which might be expected to result in adverse reactions andcomplaints. Whilst there is no widely accepted method of evaluation ofground-borne noise, there is some consensus that for levels at and above50 dB L(A) max, slow during daytime, there is likely to be significant adversereaction. For residential situations, the dB L(A)max, slow noise levels for whichthere are likely to be very little adverse comment can be taken as around30 dB L(A) max, slow during the daytime and around 25 dB L(A) max, slow duringnight time. These levels do not equate to the train pass-by beinginaudible, but are considered to be reasonable. For reference, 25 dB L(A)max, slow is approximately equivalent to 28 dB L(A) max, fast

On the basis of the above publications, Lambeth residents aretherefore suggesting 30 dB L(A) max, fast is a suitable target for TfLto aim for in designing the Northern Line Extension, and would bebetter for health than the 35 dB L(A)max, fast which TfL is currently aiming todeliver. This view is shared by the statement of Ramboll, engineeringadvisors to Lambeth Council, who in their report in December 2012 statedthat a target of 30 dB L(A) max, fast would be preferable, compared to TfLsexisting target.

Can the Northern Line Extension be designed so that operationalnoise is below 35 dB L(A) max, fast?International standards in tunnelling construction have progressed greatlyin recent years, and noise mitigation is now routinely designed intotunnels from the earliest stage as part of current best practice. As anexample, Rupert Thornley-Taylor stated to residents in January 2013 thatcontinuous welded track on resilient base plates is now the standardpractice since the development of the Jublilee Line Extension. SinceCrossrail was approved, technology has further improved, and also noiseforecasting techniques.Indeed, since Crossrail, a number of railway tunnelling projects have been

developed internationally which incorporate noise standards in excess of


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the 35 dB L(A) max, fast which TfL is working towards. A table outlining anumber of these is attached below:

Operational noise level commitments from selected recent internationaltunnelling projectsRailway system Maximum noise

limitEquivalent in dBL(A)max,fast

Dublin metro centre of town 25 dB L(A)max,slow 28Oslo metro 30 dB L(A)max,slow 32Malmo Citytuneln 30 dB L(A)max,slow 32Gothenburg Vstlnken project 30 dB L(A)max,slow 32Stockholm Citybanan 30 dB L(A)max,slow 32LUL 2012 Noise and Vibration AssetDesign Guidance reasonableendeavours

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Dublin metro suburbs 35 dB L(A)max,slow 38LUL 2012 Noise and Vibration AssetDesign Guidance maximum allowable

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Crossrail 40 dB L(A)max,slow 43Source: Experts Report on Environmental Statement for Dublin Metro North

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On this basis, it seems eminently possible for TfL to design its project to ahigher degree of tolerance than its current design reference and thiswithout needing to adopt some of the more expensive techniques fornoise mitigation, of which examples have been shown in theEnvironmental Statement.

Procurement strategyWhile Lambeth residents believe it is entirely possible for TfL to achieve,and indeed exceed, its target operational noise limit without incurringexcessive costs, we recognise that this may be all that it is willing toguarantee to residents at this stage in the procurement of contractors.In this context, it is vital for TfL to outline precisely what its procurementstrategy for tendering suitably qualified contractors, and what standardsthey will be held to as part of the tendering process. Outstandingquestions which need to be tested further during a public inquiry include:

how does TfL intend to procure contractors who are able to operate

at the cutting edge of noise mitigation technology?

What standards will TfL require to be demonstrated by contractors,as part of a wider requirement on their own behalf to demonstrate

best practical means to reduce operational noise levels? What remedies could be available to residents at a later date, if it

becomes clear that noise levels are above those predicted in theEnvironmental Statement included in the TWAO application?

Construction noiseLambeth residents recognise that it is inevitable that the tunnellingprocess will require a certain amount of temporary noise in certainlocations, which will take place in a concentrated duration. In order to

11http://www.pleanala.ie/news/na0003/rNA0003B.pdf
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ensure that this noise is kept to the minimum necessary, the followingquestions need to be tested further in a public inquiry:

What standards does TfL intend will apply to their contractors inorder to demonstrate compliance with best practical means toreduce construction noise impacts?

What is the content of a Code of Construction Practice that TfLintends to enter into with the relevant local authorities, and enforceon their contractors?

What role do local authorities intend to play in enforcing bestpractice, and what assurances can they offer to local residents thatthey are ready and willing to enforce these standards?

In particular, what standards will there be in order to limit workingtime involving significant construction noise, such that at the veryminimum it is limited to daytime during the working week.

The fact that TfL intends to seek a statutory defence to common law

claims for nuisance means that it is vital that limits on acceptable noiselevels are clearly stated as part of the TWA Order it ultimately receives.Furthermore, questions need to be asked about how TfL intends toimplement the Construction Noise and Vibration Mitigation Scheme whichis enclosed as an annex to its TWAO application:

What measures will TfL put in place to ensure that all qualifyingresidents are made aware of their rights under this scheme?

How will TfL and the local authority plan to assist affected residents

to benefit from the scheme, and in particular the right to seekcompensation, either in the shape of monetary payments,temporary resettlement and/or double-glazing?

VibrationTfL further need to answer questions about how they intend to deal withthe damage to properties along the line due to vibration and/or groundsettlement:

What arrangements do TfL intend to put in place to conduct beforeand after surveys on all homes within the limits of deviation, inorder to assess damage caused by vibration and/or groundsettlement?

What terms will be available to carry out remedial works to

properties, even if TfL initially predicts that effects of vibrationand/or settlement will be in the low-risk categories?

In what timescales can property owners expect that remedial works will becarried out and/or monetary compensation paid?


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Appendix - Note on measurementsNoise can be defined as unwanted sound. The standard measurement ofsound is in terms of the pressure changes in acoustic waves against alogarithmic (decibel) scale. In these terms, a 5dB increase represents a50% increase above the baseline, while a 10dB change represents a

doubling of the baseline level. The standard dB unit of noisemeasurement can be adjusted such that it concentrates on thebandwidths which are within the range of frequencies that can bedetected by the human ear this is represented by the dB L(A) measure.

It is not easy to compare directly constant, background noise levelsagainst intermittent, time-sensitive noises which have distinct peaks ofintensity. There are two main ways of describing such peak noises.

dB L(A)eq measures the equivalent continuous A-weighted soundpressure level over a given period of time;

dB L(A)max measures the maximum value that the A-weightedaveraged sound pressure level reaches during a measurementperiod. This can subdivided according to the measurementtechnique that divides peak sound by 1 second (dB L(A)max,slow), orby 0.125 seconds (dB L(A)max,fast).

For underground trains, the dB L(A)max,fast measurement is the mostaccurate way of measuring peak sound intensity, and a rough comparisonof the same noise level, when measured by the different techniques, isattached below.

dB L(A)max,fast dB L(A)max,slow30 2832 3035 3238 3540 38

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Annex a - Dossier on Noise and Vibration