Chapter 2.11. Noise and Vibration Assessment · 1/2/2014 · Chapter 2.11. Noise and Vibration ... 11. Noise and Vibration ... screening should be used to reduce noise levels as much

Chapter 2.11. Noise and Vibration Assessment

SBL ES: 2.11 South Bristol Link: Environmental Statement Volume 2: Noise and Vibration, July 2013

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11. Noise and Vibration 11.1. Introduction to Noise and Vibration 11.1.1. The South Bristol Link scheme would introduce new sections of road in the south-western area of

Bristol with improvements to other existing roads to provide a new route between the A370 and the A4174 in Hartcliffe. One effect of the scheme is to alter the traffic flows and composition on several existing roads in the vicinity of the scheme. The new sections of road and associated traffic changes on existing roads have the potential to alter the noise climate at nearby sensitive receptors.

11.1.2. This assessment has been carried out using the procedures described in the Design Manual for Roads and Bridges (DMRB) Volume 11 Section 3 Part 7 – Noise and Vibration. The assessment examines the effects of the Scheme on traffic noise and vibration levels in South-West Bristol. It addresses both the direct effects of traffic using the Scheme and the effects of redistributed traffic on the existing road network. The assessment takes account of traffic noise mitigation measures incorporated into the Scheme design.

11.1.3. The assessment also considers short-term temporary construction effects and describes how noise and vibration from these activities would be controlled.

11.1.4. The results of the assessment are described below with further detail provided in tables of results and noise maps in the appendices to this chapter.

11.1.5. The assessment of operational noise and vibration effects is based upon comparisons between the levels with the Scheme (Do Something) and without the Scheme (Do Minimum). These comparisons are undertaken for the opening year and for the Scheme design year, 15 years after opening. The calculated noise level changes are used to assess, via established methods for determining subjective responses to changes in traffic noise, the effects of the Scheme.

11.1.6. Noise impacts may result from changes in: • Road alignment (vertical and horizontal); • Sound generation (traffic flow, speed, gradient and road surface type); • Sound propagation (ground absorption, screening, reflection and scattering).

11.1.7. Traffic flows and the level of noise they generate fluctuate in intensity hourly, daily and seasonally, therefore the impact of traffic noise is assessed in terms of a time-averaged indicator.

11.2. Noise and Human Hearing 11.2.1. The human ear responds to a wide range of sound pressures, from 0 dB (the threshold of

hearing) up to about 130 dB (approximating to the threshold of pain).

11.2.2. Table 11–1 shows indicative noise levels associated with different noise sources. They are intended to give an appreciation of noise levels commonly experienced in various situations.

Table 11–1 Typical dB(A) Noise Levels

Noise Source dB(A) Level Rural night-time background 20-40 Quiet country bedroom at night 30-35 Quiet library 40 Quiet office, air conditioner 50 Car at 40mph at 100m 55 General office or supermarket 60


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Conversational speech at 1m 60-65 Car at 25 mph at 7.5m 70 Pavement of busy street 85 Hand held hydraulic breaker (20kg) at 7m 95 Jet aircraft at 250m 105

11.2.3. The frequency response of the human hearing system is less sensitive to low and high frequency sounds than it is in the mid frequency region. For this reason noise levels are usually expressed in dB(A) units, resulting from an electrical “A-weighting” filter having similar frequency characteristics to those of the ear.

11.2.4. The noise level response of the human hearing system is logarithmic rather than linear in nature, and able to detect a noise level difference of about 1 dB(A) between two steady sounds, when they are presented in rapid succession under controlled laboratory conditions. The smallest change in environmental noise that is generally noticed by an individual is about 3 dB(A). A 10 dB(A) change approximates to a subjective doubling or halving of loudness.

11.2.5. Noise levels close to a road fluctuate with time and may be characterised by various statistical descriptors of the noise. For example, the LA10, 1h level is the “A” weighted noise level exceeded for 10% of a 1-hour period.

11.2.6. Research has shown that the arithmetic average of the 18, 1-hour LA10 levels (depicted as LA10,18h) between 0600 and 2400 hours shows a reasonably good correlation with community responses to traffic noise. This unit is used in the UK for the assessment of road traffic noise.

11.2.7. As noise levels are logarithmic quantities, when two or more noise levels are added together, their total is the logarithmic, not arithmetic, sum of the individual levels. For example, adding together two noise levels each of 60 dB gives a total of 63 dB, not 120 dB. If the difference between two noise levels is 10 dB or more, the logarithmic sum of the two values equates to the higher of the two levels.

11.2.8. To aid the interpretation of predicted noise changes, DMRB 11:3:7 (Tables 3.1 and 3.2 in that document) gives the following classification for the magnitude of noise impacts, recognizing that it may not be applicable in all circumstances:

Table 11–2 Classification of Magnitude of Noise Impacts

Noise Change, LA10,18h Magnitude of impact (short term)

Magnitude of impact (long term)

0 No change No change 0.1 - 0.9 Negligible Negligible 1 - 2.9 Minor Negligible 3 - 4.9 Moderate Minor 5 - 9.9 Major Moderate 10 + Major Major


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11.3. Policy Context and Guidelines of Relevance

National Policy

Noise Policy Statement for England

11.3.1. The Noise Policy Statement for England (NPSE) applies to all forms of noise including environmental noise, neighbour noise and neighbourhood noise but does not apply to noise in the workplace. The Government recognises that the effective management of noise requires a co-ordinated and long term approach that encompasses many aspects of modern society.

11.3.2. The long term vision of Government noise policy is set out: Promote good health and a good quality of life through the effective management of noise within the context of Government policy on sustainable development.

11.3.3. This long term vision is supported by three aims: • avoid significant adverse impacts on health and quality of life; • mitigate and minimise adverse impacts on health and quality of life; • where possible, contribute to the improvement of health and quality of life.

11.3.4. The NPSE states in its explanatory note that the World Health Organisation (WHO) guidance should be used for assessing noise related health effects. Quoting the WHO it defines effect levels as follows: • NOEL – No Observed Effect Level. This is the level below which no effect can be detected. In

simple terms, below this level, there is no detectable effect on health and quality of life due to the noise.

• LOAEL – Lowest Observed Adverse Effect Level. This is the level above which adverse effects on health and quality of life can be detected.

11.3.5. The NPSE then extends this concept to include: • SOAEL – Significant Observed Adverse Effect Level. This is the level above which significant

adverse effects on health and quality of life occur.

11.3.6. No definition of SOAEL is provided in the NPSE, and it is described that SOAEL is likely to be different for different noise sources, for different receptors and for different times of day.

National Planning Policy Framework

11.3.7. The NPPF includes the following statements relating to noise and the requirement to take it into account in the planning process: Paragraph 109 indicates that “The planning system should contribute to and enhance the natural and local environment by: • preventing both new and existing development from contributing to or being put at

unacceptable risk from, or being adversely affected by unacceptable levels of soil, air, water or noise pollution or land instability”.

11.3.8. Section 123 indicates that “Planning policies and decisions should aim to: • avoid noise from giving rise to significant adverse impacts on health and quality of life as a

result of new development; • mitigate and reduce to a minimum other adverse impacts on health and quality of life arising

from noise from new development, including through the use of conditions; • recognise that development will often create some noise and existing businesses wanting to

develop in continuance of their business should not have unreasonable restrictions put on them because of changes in nearby land uses since they were established1;

• identify and protect areas of tranquillity which have remained relatively undisturbed by noise and are prized for their recreational and amenity value for this reason.”

1 The NPPF contains the caveat “Subject to the provisions of the Environmental Protection Act 1990 and other relevant law”.


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11.3.9. The NPPF does not therefore provide absolute limits on noise that are acceptable or unacceptable in a given situation. It does however, set out the need to use planning decisions, including through the use of conditions, to avoid or mitigate adverse impacts on health and quality of life resulting from noise.

Building Bulletin 93 Acoustic Design of Schools (BB93)

11.3.10. Building Bulletin 93 (BB93) sets out the acoustic performance requirements for educational buildings and Section 1 of BB93 provides design standards to ensure that the requirements of the Building Regulations are met.

11.3.11. Section 1 of BB93 includes limits on internal ambient noise levels in teaching and learning spaces. Ambient external noise levels have a direct effect on the noise levels within teaching spaces. BB93 sets upper limits for ambient noise levels in classrooms and playgrounds. For primary schools, the upper limit for ambient noise levels inside a classroom in 35dB LAeq, 30min. A 15dB reduction is allowed for attenuation through a partially open window, indicating that external noise levels of 50dB LAeq, 30min and below would not require further acoustic treatment of the façade. Section 1 of BB93 is currently being replaced by the document Acoustic Performance Standards For The Priority Schools Building Programme which generally retains the 35dB upper limit for ambient noise for primary school classrooms.

11.3.12. For playgrounds, Section 2 of BB93 describes that noise levels should not exceed 55dB LAeq, 30min and there should be at least one area suitable for outdoor teaching activities with noise levels which should not exceed 50dB LAeq, 30min. If these noise levels in external areas cannot be met, screening should be used to reduce noise levels as much as is practicable. Section 2 of BB93 remains current guidance.

11.4. Local Policy

Bristol

Bristol Core Strategy, adopted June 2011

Policy BCS23 Pollution

11.4.1. This policy states that development should be sited and designed in a way as to avoid adversely impacting upon environmental amenity or biodiversity of the surrounding area by reason of: • Fumes, dust, noise, vibration, smell, light or other forms of air, land, water pollution, or creating

exposure to contaminated land; and • The quality of underground or surface water bodies. • In locating and designing development, account should also be taken of: • The impact of existing sources of noise or other pollution on the new development; and • The impact of the new development on the viability of existing uses by reason of its sensitivity

to noise or other pollution.

Saved policies of the adopted Bristol Local Plan 1997

Policy ME4 Controlling the Impact of Noise

11.4.2. Policy ME4 states that: • Development which has an unacceptable impact on the environmental amenity or wildlife of

the surrounding area by reason of noise will not be permitted; and • In determining planning applications in areas of existing noise such as roads, aerodromes,

railway lines, industrial/commercial developments and sporting, recreational and leisure facilities, account will be taken of the provision of adequate sound insulation measures.

Site Allocations and Development Management Preferred Approach Document, March 2013

Policy DM35 – Noise Mitigation Noise-Generating Development


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11.4.3. Development which would have an unacceptable impact on environmental amenity or biodiversity by reason of noise will be expected to provide an appropriate scheme of mitigation.

11.4.4. In assessing such a scheme of mitigation, account will be taken of:

Existing levels of background noise and the potential for a cumulative impact; and Measures to reduce or contain generated noise; and Hours of operation and servicing. Development will not be permitted if mitigation cannot be provided to an appropriate standard with an acceptable design, particularly in proximity to sensitive existing uses or sites.

Noise-Sensitive Development

11.4.5. Noise-sensitive development in locations likely to be affected by existing sources of noise such as busy roads, railway lines, aerodromes, industrial/commercial developments, waste, recycling and energy plant and sporting, recreation and leisure facilities, will be expected to provide an appropriate scheme of mitigation to ensure adequate levels of amenity for future occupiers of the proposed development.

11.4.6. In assessing such a scheme of mitigation, account will be taken of: • The location, design and layout of the proposed development; and• Measures to reduce noise within the development to acceptable levels, including external

areas where possible; and• The need to maintain adequate levels of natural light and ventilation to habitable areas of the

development.

11.4.7. In areas of existing noise, proposals for noise-sensitive development should be accompanied by an assessment of environmental noise and an appropriate scheme of mitigation measures.

11.4.8. Development will not be permitted if mitigation cannot be provided to an appropriate standard with an acceptable design.

North Somerset

NSC Core Strategy (2012) Policy CS3

11.4.9. The NSC Core Strategy states that: “Development that would result in air, water or other environmental pollution or cause harm to amenity, health or safety will only be permitted if appropriate mitigation measures are put in place to mitigate against any potential negative impact.”

11.5. Assessment Methodology 11.5.1. The guiding principle when designing road schemes is to maximise noise decreases and

minimise noise increases. The latter aim is not always achievable, so that under the circumstances set out in the Noise Insulation Regulations 1975 as amended in 1988 an offer of noise insulation may be made.

The DMRB Assessment Method

11.5.2. Section 3 and Annex 1 of DMRB 11:3:7 describes three levels of study as follows: • Scoping to determine the need for a noise and vibration impact assessment;• Simple assessment to identify the noise and vibration impacts associated with the project;• Detailed assessment of noise and vibration impact at dwellings and other sensitive receptors

when threshold values are exceeded.

11.5.3. From the Scoping Study and inspection of the engineering drawings it is clearly evident that the project could result in threshold values being exceeded. In accordance with the flow chart shown in Figure A1.1 of the DMRB, this study therefore follows the ‘detailed assessment’ method


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described in paragraphs A1.25 to A1.38 of the DMRB. The assessment steps are outlined below: • Assessment of permanent traffic noise impacts • Assessment of permanent traffic nuisance impacts. • Assessment of permanent traffic induced vibration impacts. • Assessment of temporary impacts. • Assessment of cumulative impacts.

11.5.4. In accordance with paragraph A4.14 in DMRB 11:3:7, the noise predictions have been based upon the forecast ‘most likely’ annual average weekday traffic (AAWT) flows, speeds and percentage of heavy vehicles for the Do Minimum and Do Something situations in both the opening and design years. Only roads with flows of at least 1000 vehicles per 18 hour AAWT have been considered, in accordance with the advice in Calculation of Road Traffic Noise (CRTN). The following paragraphs explain the process in more detail.

Study Area

11.5.5. The study area is defined as being within 600m of both the Scheme boundary and any other roads in the network that are predicted to experience noise level changes of at least 1 dBLA10,18h in the opening year, out to a maximum distance of around 1km from the actual Scheme boundary.

11.5.6. Noise predictions have been conducted at a first floor receiver height of 4m above local ground level, so representing the worst case at each receiver location.

11.5.7. The predicted noise levels relate to the façades of buildings so include the 2.5dB ‘façade correction’ described in CRTN. These façade LA10,18h levels are used in the quantitative assessment of the scheme. The noise contour maps shown in Volume 3, Appendix 11.1 (E) refer to ‘free-field’ LA10,18h noise levels (i.e. without the reflective effect of a façade) and serve to illustrate the geographic extent of noise level bands and changes within the study area, which consists of open countryside and residential areas.

11.5.8. Noise levels have been calculated at residential and non-residential noise sensitive receptors, including Schools and Colleges, Churches, Hotels, Hospitals and public open spaces within the study area. The non residential receptors considered were as follows: • Amelia Nutt Clinic, New Withywood Centre, Queens Road, Bristol, BS13 8QA • Ashton Park School, Blackmoors Lane, Bristol, BS3 2JL • Ashton Park Secondary School House, Blackmoors Lane, Bristol, BS3 2JJ • Ashton Vale Primary School, Avebury Road, Bristol, BS3 2QG • Bishopsworth C of E Junior School, Ellfield Close, Bristol, BS13 8EF • Fair Furlong Primary School, Vowell Close, Bristol, BS13 9HS • Four Acres Primary School, Four Acres, Bristol, BS13 8RB • Headley Park Primary School, Headley Lane, Bristol, BS13 7QB • Highridge Infants School, Ellfield Close, Bristol, BS13 8EF • Merchants Academy, Gatehouse Avenue, Bristol, BS13 9AJ • Northleaze C of E Primary School, Brook Close, Long Ashton, Bristol, BS41 9NG • South Bristol Crematorium & Cemetery, Bridgwater Road, Bristol, BS13 7AS • St. Davids Centre, Queens Road, Bristol, BS13 8LF • St. Pius X Primary School, Gatehouse Avenue, Bristol, BS13 9AB • Sure Start, Four Acres Primary School, Four Acres, Bristol, BS13 8RB • Town & Country Lodge, Bridgwater Road, Long Ashton, Bristol, BS13 8AH • Highridge Common


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11.5.9. Noise impacts on the public rights of way are described in the Amenity Space chapter.

Comparison Years

11.5.10. The key dates for the South Bristol Link Scheme assessment are: • ‘Opening year’ 2016 • ‘Design year’ 2031

11.5.11. Noise changes associated with the South Bristol Link Scheme are assessed using the following comparisons: • Opening Effect - opening year 2016 Do Something compared to Do Minimum 2016; • Opening Year Do Minimum/Design Year Do Something Effect - design year 2031 Do

Something compared to Do Minimum 2016 (this comparison represents the combined effect of both ‘natural’ traffic growth and the Scheme);

• Do Minimum Effect - Do Minimum 2031 compared with Do Minimum 2016 (this comparison represents the change in noise due to traffic growth which would occur if the scheme were not built)

• Design Year Changes - Do Something 2031 compared with Do Minimum 2031. (this comparison represents the longer term change in noise with the scheme)

Night-time Traffic Noise

11.5.12. The DMRB requires an assessment of the impact of night-time noise where receptors would be exposed to a freefield Lnight, outside of 55dB or greater in any scenario. Night time noise levels have been calculated using the advice in the TRL report ‘Converting the UK traffic noise index LA10, 18h to EU noise indices for noise mapping’.

Traffic Noise Nuisance

11.5.13. The DMRB requires an assessment showing the change in the number of people bothered by noise. The methodology is described in the DMRB and the number of properties predicted to experience increases and decreases in nuisance is reported.

Traffic-induced Vibration

11.5.14. Traffic-induced airborne vibration may manifest itself as the rattling of badly fitted windows or light objects if the exhaust note of (usually heavy) vehicles happens to coincide with a resonant frequency of an element of the building. Airborne vibration nuisance has been assessed on the basis that ‘for a given level of noise exposure, the percentage of people bothered by vibration is 10% lower than the corresponding figure for noise nuisance’ (DMRB 11:3:7 Annex 3 paragraph A3.22).

11.5.15. Traffic-induced ground borne vibration may result from the passage of vehicles over discontinuities, such as badly reinstated trenches, in the road surface. TRL Research Report 102 concludes that with a surface irregularity of about 20mm within about 5m of a building, there was the possibility of perceptible ground borne vibrations being generated during the passage of heavy vehicles. The threshold of vibration perception is significantly lower than the threshold for building damage. As newly constructed and well maintained roads would not have surface irregularities of this magnitude, it may reasonably be concluded that ground borne vibration would not be an issue, and has not been considered further.

11.6. Calculation of Road Traffic Noise (CRTN) 11.6.1. Road traffic noise levels have been calculated at representative receptors using the method

detailed in CRTN 1988. This is the Government’s prescribed method and has been developed from extensive measurement data and validated out to distances of about 300m from trafficked roads for the purposes of the Noise Insulation Regulations. Studies undertaken by TRL in connection with the current version of DMRB 11:3:7 have shown that the CRTN algorithms can be reliably used up to 600m.


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11.6.2. The CRTN method for predicting noise from a road consists of five main stages: • Division of the road into a number of segments. • Calculation of the Basic Noise Level for each road segment, at a reference distance of 10m

away from the nearside carriageway edge. • Calculation of the noise level from each road segment at the reception point by modifying the

Basic Noise Level to take account of distance, ground attenuation and screening. • Correction of the noise level at the reception point to take account of site layout features

including reflections from buildings and façades, and the size of the source segments. • The combination of the contributions from all road segments to give the total noise level at

each reception point.

11.6.3. Traffic noise predictions have been conducted using the NoiseMap Five computer program. This program implements the algorithms contained within CRTN and the additional calculation advice described in Annex 4 of the DMRB. It has been used to build three-dimensional models of the existing road layout, the Scheme and surrounding areas including features such as buildings, landforms and barriers. Other inputs to the model include traffic flows and speeds, the nature of the road surface and the type of intervening ground between each road segment and each receiver.

11.7. Construction Noise and Vibration BS5228: Parts 1 and 2, 2009

11.7.1. Temporary noise and vibration effects may occur during the construction stages of the Scheme. Noise impacts may be quantified using the procedures given in BS 5228 Part 1, with Part 2 providing general advice on the control of vibration.

11.8. Noise Legislation The Noise Insulation Regulations 1975 as amended 1988

11.8.1. Under the circumstances specified in The Noise Insulation Regulations (NIR) 1975 (as amended 1988) residential properties may qualify for an offer of noise insulation. In respect of road traffic noise, properties may qualify if all four of the following conditions are satisfied: • the property must be within 300m of the nearest point on the carriageway; • the façade noise level due to road traffic on any highway (the ’relevant’ noise level) for the

design year, or for any intervening year if noisier, must equal or exceed 68 dBLA10,18h, (the ’specified’ level), with levels of 67.5 dBLA10,18h being rounded upwards;

• the ’relevant’ noise level for the design year, or for any intervening year if noisier, must be at least 1 dBLA10,18h higher than the pre-construction year road traffic noise level

• noise from the new or altered road must contribute at least 1 dBLA10,18h to the ’relevant’ noise level.

11.8.2. The highway authority has a duty under Regulation 3 of the NIR to make an offer of insulation to residential properties with respect to noise from a new road, and discretionary powers under Regulation 4 in respect to altered roads. Various discretionary powers are also available in relation to façades or parts of façades contiguous with a qualifying façade. The authority also has the discretionary power to offer insulation against construction noise. The Regulations apply to habitable rooms and so exclude bathrooms, toilets, halls and smaller kitchens that do not include dining areas.

The Control of Pollution Act 1974

11.8.3. The Control of Pollution Act 1974 Section 61 sets out the procedures whereby contractors may obtain ‘Prior Consent’ for construction works within agreed noise limits. Applications for such consents would be made to the local authority and would contain a construction method


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statement and the steps to be taken to minimise noise. The local authority has the power to attach conditions to any consent given.

The Environmental Protection Act 1990

11.8.4. Under Part III of the Environmental Protection Act 1990 as amended by the Noise and Statutory Nuisance Act 1993, local authorities have a duty to investigate noise complaints relating to a variety of sources, excluding road traffic noise. If the local authority is satisfied that the noise amounts to a statutory nuisance it will serve an Abatement Notice which may require that the noise be stopped altogether or limited to certain times.

The Land Compensation Act 1973

11.8.5. Part I of the Land Compensation Act 1973 includes provision for compensation for loss in property value resulting from physical agents including noise. Part II includes provision for noise mitigation measures at dwellings adjacent to new highways if certain conditions are satisfied. The Noise Insulation Regulations described above have been enacted under Part II of the Act.

The Environmental Noise (England) Regulations 2006 (as amended)

11.8.6. These regulations implement the European Commission Directive 2002/49/EC, which requires strategic noise maps and noise action plans to be produced for all sources of environmental noise, including that from road traffic using major roads. England's Noise Action Plans have identified 'Important Areas' at which measures to address environmental noise must be investigated, and those 'Important Areas with First Priority Locations' to be investigated as a priority.

11.8.7. Figure 11.1 below is derived from Map 32 on the Defra website2, and identify in dark blue the areas containing Important Areas with First Priority Locations, and in light blue, other Important Areas.

2 http://archive.defra.gov.uk/environment/quality/noise/environment/actionplan/locations.htm


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Figure 11–1 Plan of Important Areas


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11.9. Significance of operational noise impacts 11.9.1. The NPSE sets out the framework by which significance of noise impacts can be considered, but

without providing noise levels. Guidelines produced by the WHO give some noise level guidance for the onset of adverse effects. There is no guidance which defines the boundary between an adverse effect and a significant adverse effect.

11.9.2. To consider the impacts of this scheme in the context of the NPSE it is necessary to define a noise level above which noise effects are regarded as significant. This section reviews current WHO and UK guidance to define “adverse effect” levels and “significant“ levels.

Daytime Noise Levels

11.9.3. The onset of some adverse health effects is given in the WHO Guidelines for Community Noise. A level of 50dB LAeq,16hour is given for moderate annoyance in outdoor living areas, increasing to 55dB LAeq,16hour for serious annoyance, in the majority of the population. Similarly 55dB LAeq,T is set as the threshold for annoyance from external source in a school playground during playtime and this lines-up with the advice in Building Bulletin 93, Acoustic design of schools (BB93).

11.9.4. For residential dwellings internal thresholds are set at 35dB LAeq,16hour for speech intelligibility and annoyance during daytime. A 10-15dB reduction for attenuation through a partially open window is allowed which gives an external noise target of 45-50dB LAeq. The DfT consider in their TAG guidance that there is a willingness to pay for lower noise at levels above 45dB LAeq, 18hour.

11.9.5. Atkins therefore considers 45dB LAeq, 16hour to be a logical level for the onset of adverse effects in the daytime.

11.9.6. The Noise Insulation Regulations specify that a dwelling may be entitled to noise insulation when a new or improved road transport noise source causes increases in noise at a dwelling by at least 1dB to above 68dB LA10, 18h. Using a façade correction of 2.5dB and advice in the TRL report ‘Converting the UK traffic noise index LA10, 18h to EU noise indices for noise mapping’ results in a levels of 63dB LAeq, 16Hour under free-field conditions.

11.9.7. Atkins therefore considers 63dB LAeq, 16Hour to be a logical threshold for significant effects at dwellings in the daytime. There is no clear guidance for a threshold for significant daytime effects for other receptors and for the purposes of this assessment the threshold for dwellings has been applied to all receptors.

Night-time Noise Levels

11.9.8. The WHO Night Noise Guidelines for Europe (2009) indicate that there are no effects on sleep at noise levels below 30dB Lnight, outside and that effects at levels below 40dB Lnight, outside are not harmful to health and define NOEL and LOAEL accordingly.

11.9.9. The DMRB guidelines indicate that a night time noise assessment is not required if noise levels are below 55dB Lnight, outside, corresponding to the interim target in the WHO night noise guidelines.

11.9.10. Atkins therefore considers 55dB Lnight, outside to be a logical threshold for significant effects at dwellings at night. Night time impacts are only assessed at dwellings.

Significant Noise Levels

11.9.11. These levels have been summarised in the table below:


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Table 11–3 Levels of Significance

Effect Level Daytime threshold noise level Night time threshold noise level (free-field dB LAeq, 8Hr) (free-field dB LAeq, 16Hour) (facade dB LA10,

18h) Adverse effects ≥ 45 ≥ 50 ≥ 40 Significant effects ≥ 63 ≥ 68 ≥ 55

11.10. Significance of construction noise impacts 11.10.1. Part 1 of BS5228 provides a number of examples, in its Annex E, to allow the significance of

construction noise impacts to be assessed. For the purposes of this chapter, and given the construction information available, it has been taken that construction noise levels would be significant if the noise levels exceeded baseline noise levels by more than 5dB (A) and were in excess of cut-on values of 65dB LAeq, 12hour (07:00-19:00) 55dB LAeq, 4hour (19:00 23:00) or 45 dB LAeq 8hour (23:00 07:00) depending on the time of day.

11.10.2. Noise levels from construction activities are significant if baseline noise levels are exceeded by at least 5dB(A) provided that the noise from the construction activities exceeds the cut-on values. Where noise from construction activities are less than the cut-on values the impact is not significant.

11.11. Baseline Conditions 11.11.1. The South Bristol Link Scheme covers a large area and therefore the dominant noise sources are

not consistent across the entire area.

General noise climate

11.11.2. Noise sensitive receptors in the Long Ashton and Yanley areas are currently affected by traffic generated noise from the A370. Noise sensitive receptors near Ashton Vale Road or Ashton Drive are affected by noise from the A370 and the A3029, Winterstoke Road. NSRs near Ashton Drive would also be affected by rail noise. The A38, Bridgwater Road, is the dominant noise source for NSRs in the Uplands area (including South Bristol Crematorium and Yew Tree Farm) and Yanleigh Close. Currently, the most direct route between King Georges Road and the A38 is along Highridge Green. Therefore Highridge Green is one of the dominant noise sources in this area.

11.11.3. Noise measurements were taken at a number of the closest noise sensitive properties in 2012. Figure 11.2 shows the locations of the measurements taken.

11.11.4. Measured noise levels did not generally fall below 45 dB LA10 during the noise survey.


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Figure 11–2 Plan of Baseline Survey Measurement Locations

Contains Ordnance Survey data © Crown copyright and database right 2013

11.11.5. The measured noise levels support the predictions of the existing noise levels, giving further confidence to the noise modelling process. In order to provide a consistent and comprehensive assessment of the scheme, and considering the small changes in noise expected from ‘natural’ traffic growth, the ‘existing’ noise levels are considered to equate to those predicted for the ‘Do Minimum’ situation in 2016.

St. Pius Primary School

11.11.6. Existing internal and external noise levels at St. Pius Primary School conform with the requirements of Building Bulletin 93, as shown in Volume 3, Appendix 11.1 (A).

Highridge Common

11.11.7. Existing noise levels on Highridge Common are shown to be between 45 and 55dB LAeq,16Hour as shown in Volume 3, Appendix 11.1 (B).

11.12. Identification and Assessment of Noise Impacts and Likely Significant Effects

11.12.1. A total of 5937 residential and 16 non-residential NSRs within 600m of the scheme have been assessed and their noise impacts have been classified using the advice in the DMRB. Given the results of the noise survey and the uncertainty in the prediction of lower noise levels a noise floor of 45 dB LA10,18h has been applied to the results for the DMRB assessment.


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11.12.2. The results at all 5937 residential receptors are included in Volume 3, Appendix 11.1 ( F) and noise contours showing the geographical extent to changes in free field noise level are included in Volume 3, Appendix 11.1 (E). A selection of representative receptors near the scheme are shown in Volume 3, Appendix 11.1 (D).

11.12.3. To aid the qualitative assessment of properties beyond 600m from the scheme approximately 9000 further residential receptors have been included in the noise model up to a distance of approximately 1500m from the scheme.

11.12.4. All Do Something scenario calculations undertaken have accounted for two 2.5m barriers along the reserved corridor next to Waverley Gardens and St. Pius Primary School, described in Section 6, below.

11.13. Changes on Scheme Opening (2016) 11.13.1. This compares the Do Minimum and Do Something scenarios in the opening year. The results of

this assessment classify each Noise Sensitive Receptor (NSR) according to the magnitude of the short term noise impact at its façade.

Table 11–4 Opening year impacts

Change in noise level Daytime Night Time

Number of dwellings

Number of other sensitive receptors

Number of dwellings

Increase in noise level, LA10, 18h

0.1 - 0.9 1425 5 182 1 - 2.9 566 0 69 3 - 4.9 155 0 5 >=5 325 2 81

No Change = 0 1136 3 87 Decrease in noise level, LA10, 18h

0.1 - 0.9 1486 2 510 1 - 2.9 698 4 272 3 - 4.9 107 0 37 >=5 39 0 29

11.13.2. The majority of the decreases in noise are found to be along the northern part of Highridge Green between Elsbert Drive and Kings Head Lane. This is due to traffic re-routing along the scheme to get to the A38.

11.13.3. Increases of 5 dBA or more are generally at properties along the reserved corridor and King Georges Road. Increases between 3 and 5 dBA are generally along Goulston Road, Gatehouse Avenue and Highridge Green, south of Sandburrows Road.

11.13.4. At St Pius Primary School, although noise levels increase BB93 levels are still met except in the North East corner of the playing fields. In this area noise levels meet the requirement for play but not the requirement for outdoor teaching. Detailed results are included in Volume 3, Appendix 11.1 (A).

11.13.5. The proposed exchange land for the Common is predicted to experience similar noise levels to the existing Common. Parts of the Common are predicted to experience increases of at least 3dB when the scheme opens. Detailed results are included in Volume 3, Appendix 11.1 (B). Significant effects are not expected beyond 25m from the scheme. Impacts on public rights of way are described in Chapter 19, land use and soils.


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11.13.6. Of the properties further than 600m from the scheme but included in the model over 1100 would be likely to experience at least a minor decrease in noise. No properties are expected to receive a perceptible increase in noise. The properties with decreases in noise are along and near: • Highridge Green (further than 600m from the scheme) • Kings Head Lane • Church Road • Whitchurch Road • Highridge Road (further than 600m from the scheme) • Yanley Lane • The A38 north of the scheme (Part of this road is an Important Area) • The A370 south of the scheme • Properties in Long Ashton near the A370, south of the scheme

11.13.7. Analysis of the wider network shows that decreases in noise are predicted along the B3130 where approximately 35 properties will experience a minor decrease in noise. The one way system near Parson Street railway station will also experience a minor decrease in noise affecting approximately 100 properties. This area contains both Important Areas and Important Areas Containing First Priority Locations. Increases of 1 to 2 dBA are predicted on Brunel Lock Road and Cumberland Road near Cumberland basin affecting approximately 20 properties.

Table 11–5 Significance of daytime impacts within 600m of the scheme

Impact Effect Level Number of Properties Opening year Do Minimum

Number of Properties Opening year Do Something

Difference

Less than adverse effects 2707 2421 -286 Adverse effects 2747 3060 313 Significant effects 483 456 -27

11.13.8. The scheme increases the net number of properties that would experience adverse effects due to noise. However, the scheme also reduces the net number of properties experiencing significant effects due to traffic noise in the opening year.

Table 11–6 Significance of Night Time Impacts within 600m of the scheme

Impact Effect Level Number of Properties Opening year Do Minimum

Number of Properties Opening year Do Something

Difference

Less than adverse effects 3305 3098 -207 Adverse effects 2201 2420 219 Significant effects 431 419 -12

11.13.9. The significance of night time noise levels is similar to the daytime pattern with overall more properties with adverse effects and fewer properties with significant effects.

11.13.10. It should be noted that the provision of Noise Insulation (described in Section 5.5) would reduce internal noise levels at approximately 90 of the properties above the significant effect level with the scheme to below this level for both day and night periods.

Summary of Opening Effects

11.13.11. When the scheme opens perceptible increases in noise are expected at approximately 1100 sensitive receptors and perceptible decreases in noise are expected at approximately 2100 sensitive receptors.


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Table 11–7 Summary of daytime opening noise impacts

Location Perceptible increases in noise

Perceptible decreases in noise

Within 600m 1048 848 600m to 1500m 0 1100 Wider network 20 135 Total 1068 2083

11.13.12. Within 600m of the scheme there are more properties overall which would receive adverse effects and fewer properties receiving significant effects. Noise insulation would reduce internal noise levels at approximately 90 properties.

11.14. Do Minimum changes (2016 to 2031) 11.14.1. Assessing the change in noise over the design period without the scheme shows how many

properties would be affected by noise due to natural changes in traffic levels by the design year. The magnitude of the noise impact over the design period is assessed using the ‘long term’ column of the DMRB table shown in Table 5–5

Table 11–8 Do minimum impacts


Number of dwellings


Number of dwellings

Increase in noise level, LA10,

18h

0.1 - 2.9 5096 16 1162 3 - 4.9 0 0 0 5 - 9.9 0 0 0 >=10 0 0 0

No Change = 0 776 0 64 Decrease in noise level, LA10,

18h

0.1 - 2.9 65 0 46 3 - 4.9 0 0 0 5 - 9.9 0 0 0 >=10 0 0 0

11.14.2. No changes in noise level greater than 3 dBA are predicted if the scheme is not built. Changes smaller than 3dB are regarded as negligible.


Impact Effect Level Number of Properties in Opening year Do Minimum

Number of Properties in Design year Do Minimum

Difference

Less than adverse effects 2707 2524 -183 Adverse effects 2747 2825 78 Significant effects 483 588 105


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11.14.3. The natural growth in traffic over the design period would cause 78 additional properties to receive adverse noise effects and 105 additional properties to experience significant noise effects. As changes in noise are smaller than 3dB these changes are unlikely to be perceptible.

Table 11–10 Significance of Night Time impacts within 600m of the scheme


Number of Properties in Design year Do Minimum

Difference


11.14.4. The significance of night time noise levels is similar to the daytime pattern with more properties with both adverse effects and significant effects, noting that increases in noise are unlikely to be perceptible.

Summary of Do Minimum Effects

11.14.5. Changes in noise between 2016 and 2031 are expected to be negligible if the scheme is not built. Although changes in noise are expected to be negligible these changes result in additional properties receiving adverse and significant effects.

11.15. Opening Year Do Minimum/Design Year Do Something Changes

11.15.1. Table 11.11 compares the opening year Do Minimum and design year Do Something scenarios. Analysis of these changes allows for the identification of the number of NSRs affected by long term changes in noise due to the scheme and growth in traffic.

Table 11–11 Opening Year Do Minimum / Design Year Do Something impacts


Number of dwellings


Number of dwellings


18h

0.1 - 2.9 3596 10 655 3 - 4.9 352 0 30 5 - 9.9 228 1 30 >=10 161 1 53


18h

0.1 - 2.9 924 4 402 3 - 4.9 60 0 20 5 - 9.9 10 0 6 >=10 27 0 23

11.15.2. Increases of 5 dBA or more are predicted along King Georges Road and the reserved corridor. Increases of 3 to 5 dBA are generally along Ashton Drive, Cutler Road, Sandburrows Road and Dangerfield Avenue. NSRs on Whitland Road would also experience increase in noise of 3 to 5


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dBA. Decreases in noise are focused around the northern section of Highridge Green and it’s adjoining roads.

11.15.3. At St Pius Primary School, although noise levels increase BB93 levels are still met except for in the North East corner of the playing fields. In this area noise levels meet the requirement for play but not the requirement for outdoor teaching. Detailed results are included in Volume 3, Appendix 11.1 (A).

11.15.4. The proposed exchange land for the Common is predicted to experience similar noise levels to the existing Common. Parts of the Common are predicted to experience increases of at least 3dB by the design year. Detailed results are included in Volume 3, Appendix 11.1 (B). Significant effects are not expected beyond 30m from the scheme. Impacts on public rights of way are described in Chapter 19, land use and soils.

11.15.5. Of the properties further than 600m from the scheme but included in the model approximately 75 would be likely to experience at least a minor decrease in noise. These are along and near Highridge Green (further than 600m from the scheme). No perceptible increases in noise are expected.

11.15.6. Analysis of the wider area shows that no roads are predicted to have a perceptible changes in noise level due to the scheme by the design year.



Number of Properties in Design year Do Something

Difference


11.15.7. Over the design period, the net number of properties experiencing adverse effects and significant effects due to noise increases with the scheme in place.




Difference


11.15.8. The significance of night time noise levels is similar to the daytime pattern with a higher net number of properties with both adverse effects and significant effects.

11.15.9. It should be noted that the provision of Noise Insulation (described in section 5.5) would reduce internal noise levels at approximately 90 of the properties shown to receive significant effects with the scheme to levels below the significant effect level for both day and night periods.

11.15.10. Those properties which are shown to receive significant effects with the scheme, but which do not qualify for noise insulation, have increases in noise less of than 3dB, and so it is unlikely that the change in noise would be perceptible.


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Summary of Opening Year Do Minimum/Design Year Do Something Effects

11.15.11. By the design year perceptible increases in noise are expected at approximately 740 sensitive receptors and perceptible decreases in noise are expected at approximately 170 sensitive receptors. This takes into account both the scheme and natural traffic growth.

Table 11–14 Summary of daytime noise impacts by the design year

Location Perceptible increases in noise Perceptible decreases in noise Within 600m 743 97 600m to 1500m 0 75 Wider network 0 0 Total 743 172

11.15.12. There is a net increase in the number of properties with adverse effects and with significant effects, although the provision of noise insulation reduces internal noise levels at approximately 90 properties which would receive significant effects. At the remaining properties predicted to receive significant effects changes in noise are unlikely to be perceptible.

11.16. Design Year Changes 11.16.1. Compares the design year Do Minimum and design year Do Something scenarios.

Table 11–15 Design Year impacts


Number of dwellings


Number of dwellings


18h

0.1 - 2.9 2680 7 352 3 - 4.9 173 0 7 5 - 9.9 207 1 72 >=10 141 1 10


18h

0.1 - 2.9 1865 5 733 3 - 4.9 81 0 25 5 - 9.9 24 0 4 >=10 28 0 25

11.16.2. Increases of 5 dBA or more are predicted along King Georges Road, Highridge Green and the reserved corridor. Increases of 3 to 5 dBA are generally along Goulston Road, Highridge Green, Sandburrows Road and Dangerfield Avenue. NSRs on Elsbert Drive would also experience increase in noise of 3 to 5 dBA. Decreases in noise are focused around the northern section of Highridge Green and it’s adjoining roads.

11.16.3. At St Pius Primary School, although noise levels increase BB93 levels are still met except for in the North East corner of the playing fields. In this area noise levels meet the requirement for play but not the requirement for outdoor teaching. Detailed results are included in Volume 3, Appendix 11.1 (A).


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11.16.4. The proposed exchange land for the Common is predicted to experience similar noise levels to the existing Common. Parts of the Common are predicted to experience increases of at least 3dB by the design year. Detailed results are included in Volume 3, Appendix 11.1 (B). Significant effects are not expected beyond 30m from the scheme. Impacts on public rights of way are described in Chapter 19, land use and soils.

11.16.5. Of the properties further than 600m from the scheme but included in the model over 80 would be likely to experience decrease in noise of at least 3dBA. No increases in noise greater than 3dBA are expected. The properties with perceptible decreases in noise are along and near: • Highridge Green (further than 600m from the scheme) • Kings Head Lane • Yanley Lane

11.16.6. In the wider road network changes in noise of at least 3dB are not expected.


Impact Effect Level Number of Properties in Design year Do Minimum


Difference

Less than adverse effects

2524 2155 -369

Adverse effects 2825 3170 345 Significant effects 588 612 24

11.16.7. In the design year, the scheme would cause a net increase in the total number of properties experiencing adverse effects and significant effects.

11.16.8. It should be noted that the provision of Noise Insulation (described in section 5.5) would reduce internal noise levels at approximately 90 of the properties shown to receive significant effects with the scheme to levels below the significant effect level for both day and night periods.

11.16.9. Those properties which are shown to receive significant effects with the scheme, but which do not qualify for noise insulation, have increases in noise less than 3dB, and so it is unlikely that the change in noise would be perceptible.


Impact Effect Level Number of Properties in Design year Do Minimum


Difference

Less than adverse effects

3177 2884 -293

Adverse effects 2221 2485 264 Significant effects 539 568 29

11.16.10. The significance of night time noise levels is similar to the daytime pattern with a higher net number of properties with both adverse and significant effects. Similarly, changes in noise at properties which are shown to receive significant effects with the scheme, but which do not qualify for noise insulation, are less than 3dB, and are unlikely to be perceptible.

Summary of Design Year Effects

11.16.11. A comparison in the design year shows that perceptible increases in noise are expected at approximately 520 sensitive receptors and perceptible decreases in noise are expected at approximately 210 sensitive receptors.


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Table 11–18 Summary of daytime noise impacts in the design year

Location Perceptible increases in noise Perceptible decreases in noise Within 600m 743 97 600m to 1500m 0 75 Wider network 0 0 Total 523 213

11.16.12. The changes in noise result in a net increase in the number of properties with adverse effects and significant effects, although the provision of noise insulation reduces internal noise levels at approximately 90 properties which would receive significant effects. At the remaining properties predicted to receive significant effects changes in noise are unlikely to be perceptible.

11.17. Noise Insulation Regulations Assessment 11.17.1. No formal offers of noise insulation can be made until after the completion of the statutory

processes and the finalisation of the detailed engineering design of the scheme.

Regulation 3

11.17.2. Under Regulation 3 of the NIR 1975 as amended 1988, there is 1 property that would potentially qualify for noise insulation. This property is adjacent to the reserved corridor.

Regulation 4

11.17.3. Under Regulation 4 of the NIR 1975 as amended 1988, there are 88 properties that would potentially qualify for noise insulation. These properties are along King Georges Road, Highridge Green, Highridge Road and Queens Road.

11.18. Noise Nuisance Assessment 11.18.1. The DMRB states that noise nuisance assessments should be undertaken in the following

scenarios: • Opening Year Do Minimum to Design Year Do Minimum • Opening Year Do Minimum to Design Year Do Something

11.18.2. The noise nuisance assessment determines the change in the proportion of the population that would be bothered by noise, reported in Table 11–19 below. The assessment is limited to properties within 600m of the scheme due to the reliability of the noise prediction method beyond this distance.

Table 11–19 Change in Noise Nuisance at residential properties within 600m of the scheme

Change in nuisance level

Do-minimum Number of dwellings

Scheme Number of dwellings

Increase in nuisance level >0 - <10 % 5096 2395 10 - <20 % 0 788 20 - <30 % 0 674 30 - <40 % 0 263 >=40 % 0 217


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No Change =0 % 776 579 Decrease in nuisance level

>0 - <10 % 65 991 10 - <20 % 0 24 20 - <30 % 0 6 30 - <40 % 0 0 >=40 % 0 0

11.18.3. The table above shows that if the scheme were not built there would be a small increase in noise nuisance at the majority of properties due to natural traffic growth by the design year.

11.18.4. With the scheme in place there would be fewer properties which receive an increase in nuisance than if the scheme were not built, there being approximately 1000 properties where noise nuisance would decrease. At around 2000 properties increases in nuisance would be in a higher nuisance band than if the scheme were not built.

11.18.5. The DMRB method for nuisance assessment takes a worst case approach. A change in noise in the short term is shown to give a greater change in nuisance than a gradual change in noise over a period of years. The table reports the highest levels of nuisance, which for increases in noise occurs on scheme opening.

11.19. Mitigation 11.19.1. The scheme design includes two 2.5m high noise barriers near Waverley Gardens and St Pius

Primary School. As part of the noise mitigation design for the scheme noise barriers were also modelled at property boundaries along the reserved corridor. The noise benefits at these properties were outweighed by adverse landscape and visual impacts and therefore these barriers are not included in the scheme design. The approximate position of the barriers is shown in red in the following figure.

Figure 11–3 Approximate location of noise barriers


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11.19.2. The majority of major impacts away from the reserved corridor are located along King Georges Road and Highridge Green. Due to access requirements at these properties, noise barriers are not a practical solution for mitigation. In these locations the only practical method for reducing noise is the provision of noise insulation.

11.19.3. Typically noise insulation could provide noise reductions of 20-30dB within properties depending on the existing glazing and ventilation at these properties. It should be noted that the Noise Insulation Regulations require that ventilation would need to be provided in any room where noise insulation is to be installed. As the treatment is of the building façade this measure would not affect noise levels outside the properties, but internal noise levels are likely to be acceptable with noise levels being below the significant effect level..

11.20. Vibration assessment 11.20.1. The DMRB states that traffic induced airborne vibration is likely to affect a very small proportion of

the population at noise exposure levels below 58dB LA10. The method for assessing vibration is also based on data up to 40m from a scheme and the DMRB advises that caution should be exercised when assessing properties beyond this distance.

11.20.2. This assessment considers all properties within 600m of the scheme that experience noise levels of at least 58dB LA10 and assesses the change in the proportion of the population that would be bothered by traffic induced airborne vibration. The vibration assessment is undertaken for the following scenarios: • Opening Year Do Minimum to Design Year Do Minimum • Opening Year Do Minimum to Design Year Do Something

Table 11–20 Airborne vibration assessment

Change in nuisance level

Do-minimum Number of dwellings

Scheme Number of dwellings

Increase in nuisance level >0 - <10 % 1695 1172 10 - <20 % 0 44 20 - <30 % 0 54 30 - <40 % 0 0 >=40 % 0 0

No Change =0 % 4177 4058 Decrease in nuisance level

>0 - <10 % 65 580 10 - <20 % 0 29 20 - <30 % 0 0 30 - <40 % 0 0 >=40 % 0 0

11.20.3. The table shows that if the scheme were not built the majority of properties would experience no change in airborne vibration nuisance.

11.20.4. If the scheme were built there would be fewer properties which would receive an increase in airborne vibration nuisance. The properties which are predicted to receive increases in airborne vibration nuisance greater than 10% are all within 40m of the scheme and are predominantly on King Georges Road.


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11.21. Cumulative Effects 11.21.1. To assess the possible cumulative effects resulting from the operation of the South Bristol Link

and the Ashton Vale to Temple Meads (AVTM) schemes on the South Bristol Link receptors, additional calculations have been undertaken for the 2016 and 2031 do-something scenarios, which included traffic data associated with the AVTM. These are reported in detail in Volume 3, Appendix 11.1 (C).

Opening Effects with AVTM

11.21.2. With AVTM in place. when the scheme opens perceptible increases in noise are expected at approximately 1000 sensitive receptors and perceptible decreases in noise are expected at approximately 2150 sensitive receptors. Although there are slightly fewer increases in noise and slightly more decreases in noise than for the SBL scheme in isolation the overall noise impacts are regarded as similar.

Opening Year Do Minimum/Design Year Do Something Effects with AVTM

11.21.3. By the design year perceptible increases in noise are expected at approximately 750 sensitive receptors and perceptible decreases in noise are expected at approximately 170 sensitive receptors. When compared with the scheme the noise impacts are similar.

Design Year Effects with AVTM

11.21.4. A comparison in the design year shows that perceptible increases in noise are expected at approximately 530 sensitive receptors and perceptible decreases in noise are expected at approximately 170 sensitive receptors. When compared with the scheme the noise impacts are similar.

11.21.5. The transport assessment qualitatively indicates that the cumulative assessment of the South Bristol Link scheme with the Ashton Vale to Temple Meads (AVTM) scheme and the North Fringe to Hengrove Package (NFHP) scheme are generally minimal compared with the South Bristol Link scheme in isolation. Therefore, it is unlikely that the noise impacts at receptors affected by the South Bristol Link scheme would be significantly different if the three schemes were operating together.

11.22. Construction Noise and Vibration 11.22.1. Noise and vibration impacts would vary throughout the construction period, and are dependent on

the contractor’s chosen method of working and on the timing and phasing of certain operations.

11.22.2. An indicative construction noise assessment has been carried out using guidelines set out in BS 5228. Assumptions have been made regarding the plant to be used on site and noise levels have been estimated using the data and procedures given in BS 5228. The table of the calculations undertaken is included in Volume 3, Appendix 11.1 (G), and a summary is given below.

11.22.3. The highest predicted noise level for the nearest receptor for each phase of the works has been considered as the potential construction noise level for this assessment. This approach is considered to provide worst case construction noise levels for each receptor. Receptors which are at a greater distance than indicated would have lower impacts.

11.22.4. The highest noise levels given would occur when the nosiest items of plant operate at the same time at the closest distance to the receptor. In reality the construction plant would be intermittent and mobile and construction noise levels are likely to be lower for the majority of the time. The noise control measures specified in the CEMP are also likely to be able to lower the noise levels shown.


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Table 11–21 Noise level calculations - summary table

Location (Chainage) Distance to nearest receptor

Highest construction noise level at receptor, dB(A)

Significant daytime noise effects?

A370 junction 175m 57 No Park & Ride link 160m 58 No A370 to NR underbridge 110m 62 No Network Rail underbridge 120m 62 No Parson Street to A38 200m 55 No Colliters Brook 110m 62 No A38 junction 70m 67 Unlikely A38 to Highridge Common 75m 66 Unlikely Highridge Common 28m 77 Yes King Georges Road 10m 88 Yes Reserved Corridor 10m 88 Yes Hareclive Rd / Cater Rd 35m 74 Yes

11.22.5. Significant noise impacts from construction activities are likely along the scheme corridor, particularly along King Georges Road, the reserved corridor, the Highridge Common area and in the Hareclive Road / Cater Road area. As has been noted earlier in this chapter, noise barriers are not viable along King Georges Road or Highridge Green due to access requirements.

11.22.6. Impacts in the evening and during the night would depend on the particular works being undertaken. Night-time and evening works are planned at the Network Rail underbridge. In other areas night-time working would be limited to specific short term activities which cannot be undertaken during the day.

11.22.7. Diversions will be required whilst construction work is carried out on King Georges Road and Highridge Green. This will cause temporary changes in traffic flows in the local area which may give rise to short term noise impacts.

11.22.8. Construction vibration impacts are unlikely to be significant. Whilst certain construction activities may generate perceptible vibration level these are unlikely to be of sufficient magnitude to cause damage to buildings. The vibration impacts from relevant activities would be assessed and controlled through the CEMP, and the method of construction would be selected such that vibration impacts would be minimised.

11.22.9. Noise and vibration from construction activities is controlled through the CEMP. This will specify appropriate noise control measures for the construction methods being used and taking into account the proximity of noise sensitive receptors and the timing and duration of works. In any case it is industry practice to use Best Practicable Means to minimise noise and vibration impacts. Based on the information available appropriate planning and the use of Best Practicable Means would minimise the noise and vibration impacts and it is likely that an acceptable schedule of works could be agreed.

11.23. Conclusions 11.23.1. The South Bristol Link scheme would introduce new sections of road in the south-western area of

Bristol with improvements to other existing roads to provide a new route between the A370 and the A4174. One effect of the scheme is to alter the traffic flows and composition on several existing roads in the vicinity of the scheme. The new sections of road and associated traffic changes on existing roads have the potential to alter the noise climate at nearby sensitive receptors.


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11.23.2. Analysis of the noise impacts has been undertaken and reported following the guidance for a Detailed assessment, described in the DMRB. Noise levels have been predicted both with and without the scheme in both the scheme opening year (2016) and in the design year (2031). Increases and decreases in noise would give rise, respectively, to increases and decreases in nuisance.

11.23.3. Two 2.5m high noise barriers have been included in the scheme design to reduce the noise impacts within the reserved corridor. Major noise increases are expected along King Georges Road where noise barriers are not practical. Some properties along this section are likely to meet the requirements of the Noise Insulation Regulations. Typical noise insulation could achieve noise reductions of 20-30dB within the properties depending on the existing glazing and ventilation.

Opening Effects

11.23.4. The beneficial and adverse noise impacts of the scheme are greatest in the opening year with larger numbers of receptors with perceptible increases and decreases in noise than compared with the longer term effects.

11.23.5. On opening there are approximately 1100 properties with perceptible increases in noise and approximately 2100 properties with perceptible decreases in noise. The greatest noise increases occur in the reserved corridor and the greatest decreases in noise occur along parts of Highridge Green. Decreases in noise are expected at some of the Important Areas near the scheme. With the scheme in place, overall there would be more properties experiencing adverse effects and fewer properties experiencing significant effects. The provision of noise insulation would reduce internal noise levels at approximately 90 properties to levels below those where significant effects would occur.

Do Minimum Effects

11.23.6. If the scheme were not built all changes in noise would be negligible although traffic growth over the design period would give rise to additional properties with adverse effects and significant effects.

Design Year Effects

11.23.7. By the design year the project would result in there being more perceptible increases in noise than perceptible decreases in noise. A comparison in the design year shows that there are approximately 520 perceptible increases in noise all within 600m of the scheme and 210 perceptible decreases in noise occurring within 1500m of the scheme. Perceptible changes in noise are not expected at any of the Important Areas.

11.23.8. Although there are decreases in noise with the scheme in place there is a net increase in the number of properties which would experience both adverse effects and significant effects. However, the provision of noise insulation would reduce internal noise levels at approximately 90 properties to levels below those where significant effects would occur. Changes in noise are predicted to be imperceptible at any properties predicted to receive significant effects with the scheme which do not qualify for noise insulation.

Cumulative Effects

11.23.9. Within the scheme study area the results of the cumulative assessment, including the AVTM scheme are similar to the SBL scheme in isolation. In the opening year impacts would be slightly better than considering the scheme in isolation. By the design year the inclusion of AVTM has an almost negligible effect on the noise results. It is also considered unlikely that there will be significant cumulative effects with the NFHP scheme.

Construction Effects

11.23.10. An estimate of construction noise impacts has been undertaken, showing that significant effects may occur at locations near to the scheme. These would be controlled through the CEMP and


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Best Practicable Means would be used to minimise adverse effects such that an acceptable schedule of works could be agreed.

Summary

11.23.11. In summary the scheme gives rise to both major increases in noise and major decreases in noise. Where possible noise impacts are reduced by a combination of roadside noise barriers and the provision of noise insulation. When the scheme opens there would be more properties with perceptible decreases in noise than with perceptible increases in noise. Taking noise insulation into account there would be fewer properties exposed to significant internal effects in the design year than if the scheme were not built.


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