Noise and Vibration
Introduction
This chapter describes the methodology followed and potential impacts identified for the noise and vibration assessment of the A75 Springholm and Crocketford Improvements (hereafter referred to as “the proposed scheme”). This assessment has been undertaken with reference to Design Manual for Roads and Bridges (DMRB) LA 111 - Noise and vibration (revision 2) (hereafter referred to as “DMRB LA 111”) and other relevant standards and guidance set out within this chapter.
Legislative and Policy Framework
This section provides a summary of the legislation and policies relevant to this noise and vibration assessment.
Legislation
The following legislation is relevant to this noise and vibration assessment.
Noise Insulation (Scotland) Regulations 1975 and Land Compensation (Scotland) Act 1973
In the case of noise from new or altered roads the ‘Noise Insulation (Scotland) Regulations 1975’ (NISR) provides certain mandatory and discretionary powers in relation to the provision of noise insulation to affected dwellings.
The methodology provided in ‘The Memorandum on the Noise Insulation (Scotland) Regulations 1975’ Regulations 3 and 6 should be used to establish eligibility of receptors. Under Regulation 3 of the NISR, noise from a new highway that conditionally exceeds 68 dB LA 10,18h requires a roads authority to make offers of insulation to eligible dwellings. The conditions are that the noise level must also increase by at least 1 dB, with a 1 dB contribution to the increase in noise level to be from the new or altered roads.
Note: The index adopted by the UK Government to quantify road traffic noise is the L A10,18h , which is the arithmetic mean of the noise levels exceeded for 10% of the time in each of the 18 one-hour periods between 6am and midnight.
Control of Pollution Act 1974
The Control of Pollution Act 1974 controls waste disposal, water pollution and noise atmospheric pollution.
Under the act, the local authority may serve notice imposing requirements as to how and when works to roads are carried out, in order to limit construction noise arising from such works and having regard to the need to ensure the best practicable means are employed to minimise noise.
The act sets out the procedure for applying to the local authority for consent prior to carrying out works with the intention of agreeing noise and vibration limits in advance of works and avoiding the need for service of a notice for control of noise under the act.
Environmental Protection Act 1990
The Environmental Protection Act 1990 provides for the control of air pollution, land wastes, nuisance and radioactive substances in order to protect the environment. Part III of the act defines what may constitute a statutory nuisance (including noise prejudicial to health), what activities are specifically exempt, the procedures the local authority must follow for service of notices to deal with abatement of statutory nuisances and the penalties payable for conviction of causing a statutory nuisance. Local authorities have a duty under the act to inspect their area from time to time to detect statutory nuisances.
The Noise and Statutory Nuisance Act 1993
This Act amended Part III of the Environmental Protection Act 1990 by placing additional definitions in the list of statutory nuisances in Section 79 of that Act. The definitions relate to nuisance caused by vehicles, machinery and equipment in the road.
Environmental Noise (Scotland) Amendment Regulations 2018
The Environmental Noise (Scotland) Regulations 2006 (amended by the Environmental Noise (Scotland) Amendment Regulations 2018) implements the obligations of the Scottish Government established within the Environmental Noise Directive (END).
The regulations relate to the assessment and management of environmental noise. They require the production of strategic noise maps showing peoples exposure to environmental noise from major roads, railways and airports and in urban areas.
Action plans must also be developed based on the noise maps to reduce noise levels where necessary and to preserve environmental noise quality in areas where it is good.
National Policy
The following national policy is relevant to this noise and vibration assessment.
Planning Advice Note 1/2011: planning and noise
The Scottish Government’s Planning Advice Note 1/2011: planning and noise (PAN) provides advice on the role of the planning system in helping to prevent and limit the adverse effects of noise. Information and advice on noise impact assessment (NIA) methods is provided in the associated Technical Advice Note.
The PAN promotes the principles of good acoustic design and a sensitive approach to the location of new development, to ensure that quality of life is not unreasonably affected, and that new development continues to support sustainable economic growth.
The PAN provides advice on the assessment of some source of noise. In relation to road traffic noise impact assessments for the development or improvement of major roads predictions of the effects of road traffic noise can be useful.
Assessment of Noise: Technical Advice Note (March 2011)
The Scottish Government’s Assessment of Noise: Technical Advice Note (TAN) provides guidance to assist in the technical evaluation of noise assessment. It does not provide prescriptive guidance on noise assessment. The TAN defines noise impact assessment as a process which identifies and evaluates the key noise impacts of a development for the purposes of informing the design and planning decision process. The noise assessment should assess the change in the acoustic environment that will be brought about by the proposed scheme.
For a quantitative assessment of noise impacts, the significance of the noise impact at receptors can be determined from the sensitivity of a receptor and the magnitude of change relative to an absolute threshold or relative to the pre-existing ambient noise level. Guidance on the appropriate sensitivity of a receptor is given, and a scale of magnitude is provided in relation to change in road traffic noise in a residential area in terms of L A10,18hr decibels (dB).
Local Policy and Plans
Dumfries and Galloway Local Development Plan 2 provides the local planning framework and includes the following policy in relation to noise and vibration:
- Policy OP1 Development Considerations: Development proposals should be compatible with the character and amenity of the area and should not conflict with nearby land uses. There are a range of issues which may result from the development, including noise and vibration, which will be a material consideration in the assessment of proposals.
Assessment Methodology
The methodology that has been used for this high-level assessment is described in this section. The improvement strategies have been assessed qualitatively with reference to the assessment methodology described in DMRB LA 111.
There are six improvement strategies under consideration, which run between Castle Douglas and Dumfries alongside or in parallel to the existing A75. There are various start and end points of the improvement strategies with the southernmost being Allanton Roundabout, and the northernmost being Drummore roundabout at the start of the existing dualled section, east of Lochfoot Burn.
DMRB LA 111 paragraph 2.1 states:
- ’During options identification, the level of detail of a noise and vibration assessment shall be proportionate to the quality of data available and the risk of likely significant effects occurring‘.
As is proportionate for DMRB Stage 1, the assessment of improvement strategies is qualitative with discussion of the possible impacts within each improvement strategy.
Data Sources
Assumptions and Limitations
Assumptions
It is assumed that the Scotland Noise maps can provide an indication of the existing noise level to inform a high-level summary of the baseline.
It is assumed that operational vibration from road traffic would be scoped out of assessment at DMRB Stage 2, in line with the recommendations of DMRB LA 111.
Limitations
There is no information available regarding likely construction phase activities, and at this stage the specific location of likely construction activities is also not known. An assessment of likely noise from construction activities has therefore not been carried out. This is not considered to be a risk to the selection of an improvement strategy as construction methods are likely to be similar for all improvement strategies and are temporary.
There was no traffic data for the improvement strategies available to inform the assessment. The study area is therefore based on a distance of 600m from the improvement strategies at this stage. This is not considered to be a risk to the selection of an improvement strategy as the same assumption is made for all improvement strategies.
Study Area
Instructions on how to set the study area for an assessment of noise and vibration are provided within DMRB LA 111. The distances used for the study areas have been informed by professional judgement and correspond to the distance where it is considered that receptors could potentially be affected by noise or vibration.
For construction noise, a study area of 300m from construction activities is considered appropriate. For construction vibration, any receptors within 100m of an activity likely to generate a noticeable level of vibration would be considered. The construction traffic (such as traffic generated due to the construction of the proposed scheme but excluding non-construction related traffic using a diversion route) study area is an area 50m from the kerb line of public roads with the potential for an increase in noise level of 1dB(A) or more as a result of the addition of construction traffic to existing traffic levels. A study area for diversion routes is defined to include a 25m width from the kerb line of any diversion route.
The study area for operational road traffic should include the area within 600m of new road links or road links physically changed or bypassed by the proposed scheme. In addition, any roads outside of this area where there is a change in the short term of more than 1dB(A) as a result of the proposed scheme would also be considered when traffic data is available to inform this, and on these links the receptors within 50m should be included within the assessment. This is not known at this stage as traffic data is not available.
The study areas relevant to this DMRB Stage 1 assessment are shown on Figure 11-1.
Baseline Conditions
The baseline conditions are from a desktop review of available information. For an assessment of noise and vibration, sensitive receptors would typically be where people are, so such locations as dwellings, schools, hospitals and community facilities. A building alone can be sensitive to structural damage from vibration, although the building would need to be very close to certain construction works for this to occur.
The existing noise climate in the vicinity of the proposed scheme is dominated by road traffic noise from the A75. An indication of the noise level can be found in the strategic Noise map produced by the Scottish Government. These maps indicate a daytime noise level of 65-70dB L DAY (L DAY is a noise indicator based upon annual average A-weighted long-term sound over the day-time period (07:00-19:00)) adjacent to the A75 between Springholm and Crocketford, with the night-time noise being around 60-65dB L NIGHT (L NIGHT is a noise indicator for sleep disturbance based upon annual average A-weighted long term sound over the night-time period (23:00 – 07:00)). Further from the A75 road traffic levels will be lower, and no other major noise sources have been identified.
Transport Scotland has identified areas where the 1% of the population that are affected by the highest noise levels from roads are located, according to the results of the strategic noise mapping, and these are Candidate Noise Management Areas (CNMAs). There are no CNMAs located within 600m of the improvement strategies.
There are residential dwellings in the settlements of Brae, Crocketford and Springholm along the A75 within the DMRB Stage 1 Assessment Corridor, as well as smaller groups and individual residential dwellings. There is also Springholm Primary School, in Springholm, approximately within 45m of the A75 that currently experience road traffic noise from the A75.
Within 600m of the improvement strategies there are the settlements of Milton, Kirkpatrick Durham, Hardgate, Haugh of Urr, Old Bridge of Urr, Clarebrand and the northern side of Castle Douglas. There are also further smaller groups and individual residential dwellings as well as Hardgate Primary School and Castle Douglas Medical Group GP surgery.
Potential Impacts
Construction Phase
The assessment of impacts from construction noise and vibration considers that there is the potential for adverse impacts within distances of 300m and 100m respectively from construction works. The locations of any construction works are not known at DMRB Stage 1, with broad improvement strategies under consideration. Furthermore, likely construction phase activities are not currently known, and these are likely to differ depending on the improvement strategy selected.
Potential impacts during construction, including those from construction traffic and possible haul routes, will therefore be reviewed at the next stage of assessment when more information regarding route options and potentially construction phase activities are known.
Operation Phase
A description of the likely impacts from road traffic noise for each improvement strategy is provided in this section.
Improvement Strategy 1
Improvement Strategy 1 is offline and leaves the existing A75 at Allanton Roundabout. It then runs north-west of Springholm, Auchenreoch Loch and Crocketford, before rejoining the existing A75 at Drummore Roundabout. It would involve the construction of a new carriageway between the Allanton and Drummore roundabouts. The total length of the improvement strategy is approximately 19km.
There is the potential for there to be reductions in road traffic noise for noise sensitive receptors that are within 600m of the current section of the A75 that would be bypassed by Improvement Strategy 1. This includes residential dwellings in the settlements of Brae, Crocketford and Springholm along the A75 as well as smaller groups and individual residential dwellings and a primary school in Springholm.
Improvement Strategy 1 would introduce road traffic noise into areas where there are no existing major sources of road traffic noise. In particular, noise sensitive receptors within 600m of the route would be likely to experience increases in road traffic noise. This includes moving the main source of road traffic noise from the eastern side of Crocketford to the western side and increasing road traffic noise to the settlements of Old Bridge of Urr, Kirkpatrick Durham and Clarebrand as well as smaller groups and individual residential dwellings.
Improvement Strategy 2
Improvement Strategy 2 is offline and leaves the existing A75 at a location approximately 2.7km south of Springholm. It then runs north-west of Springholm, Auchenreoch Loch and Crocketford before rejoining the existing A75 at a location approximately 0.8km north-east of the settlement of Brae. It would involve the construction of a new carriageway between the existing A75 / B794 junction and the existing A75 to north-east of Brae. The total length of the improvement strategy is approximately 12.4km.
There is potential for reductions in road traffic noise for noise sensitive receptors that are within 600m of the current section of the A75 that would be bypassed by Improvement Strategy 2. This includes residential dwellings in the settlements of Brae, Crocketford and Springholm along the A75 as well as smaller groups and individual residential dwellings and a primary school in Springholm.
Improvement Strategy 2 would introduce road traffic noise into areas where there are no existing major sources of road traffic noise. In particular, noise sensitive receptors within 600m of the route would likely experience increases in road traffic noise. This includes moving the main source of road traffic noise from the eastern side of Crocketford to the western side and increasing road traffic noise to the eastern side of the settlement of Kirkpatrick Durham as well as small groups and individual residential dwellings.
Improvement Strategy 3
Improvement Strategy 3 is online and follows the route of the existing A75 from the south of Springholm to the north of the Crocketford. This includes the sections of existing A75 subject to the 30mph speed restriction. The total length of the improvement strategy is approximately 5.4km.
There are noise sensitive receptors in the vicinity of the A75 in this section within Crocketford and Springholm, including Springholm Primary School, as well as smaller groups and individual residential dwellings that may experience increases in road traffic noise.
Improvement Strategy 4
Improvement Strategy 4 is offline and leaves the existing A75 at a location approximately 0.8km south-west of Springholm. It then runs to the south-east of Springholm, parallel to the existing A75 for approximately 1.2km, before continuing south-east of Crocketford and re-joining the existing A75 approximately 0.6km north-east of Crocketford. It would involve the construction of a new carriageway between the south-west of Springholm and the north-east of Crocketford. The total length of the improvement strategy is approximately 6.0km.
There is potential for a reduction in road traffic noise for noise sensitive receptors that are within 600m of the current section of the A75 that would be bypassed by Improvement Strategy 4. This includes residential dwellings in the settlements of Crocketford and Springholm along the A75 as well as smaller groups and individual residential dwellings and a primary school in Springholm.
Improvement Strategy 4 would increase road traffic noise for a smaller number of individual and groups of dwellings within 600m of its alignment to the east where the A75 would be brought closer to sensitive receptors.
Improvement Strategy 5
Improvement Strategy 5 is offline and leaves the existing A75 approximately 0.4km south of the Ramhill Bridge over Urr Water. It then runs south-east of Springholm and passes south-east of Auchenreoch Loch and Crocketford and north-west of Milton Loch before rejoining the existing A75 near the settlement of Brae. It would involve the construction of a new carriageway between the south of Ramhill Bridge and the south of Brae. The total length of the improvement strategy is approximately 11km.
There is potential for reductions in road traffic noise for noise sensitive receptors that are within 600m of the current section of the A75 that would be bypassed by Improvement Strategy 5. This includes residential dwellings in the settlements of Crocketford and Springholm, including the primary school, as well as smaller groups and individual residential dwellings.
Improvement Strategy 5 would increase road traffic noise for a smaller number of individual and groups of dwellings within 600m of its alignment to the east where the A75 would be brought closer to noise sensitive receptors.
Improvement Strategy 6
Improvement Strategy 6 is offline and leaves the existing A75 at Allanton Roundabout. It then follows a route south-east of Springholm, Crocketford and Milton Loch. It also passes to the east of Haugh of Urr, Hardgate and Milton, running parallel to the Old Military Road for the majority of the route, rejoining the existing A75 at the Drummore Roundabout. It would involve the construction of a new carriageway between the Allanton to Drummore roundabouts. The total length of the improvement strategy is approximately 17.2 km.
There is potential for a reduction in road traffic noise for noise sensitive receptors that are within 600m of the current section of the A75 that would be bypassed by Improvement Strategy 6. This includes residential dwellings in the settlements of Brae, Crocketford and Springholm along the A75 as well as smaller groups and individual residential dwellings and a primary school in Springholm.
Improvement Strategy 6 would introduce road traffic noise into areas where there are no existing major sources of road traffic noise, where noise sensitive receptors within 600m of the route would be likely to experience increases in road traffic noise. This includes the settlements of Haugh of Urr, Hardgate, Milton and Lochfoot as well as smaller groups and individual residential dwellings. Improvement Strategy 6 is also within 600m of Hardgate Primary School and Lochrutton Primary School where increases in road traffic noise would be likely.
Design, Mitigation and Enhancement Measures
Construction Phase
Construction noise and vibration mitigation would occur as a matter of course due to legislative requirements or standard sector practices. Prior to construction, an Environmental Management Plan (EMP) would be prepared and implemented. This would include the relevant construction noise criteria and any proposed monitoring during construction. This would also contain details of good practice measures associated with mitigating potential noise and vibration impacts. Appropriate mechanisms to communicate with local residents would be developed to highlight potential periods of disruption. These mechanisms could include web-based updates or articles, newsletters and radio announcements.
Operation Phase
When considering any required operational noise mitigation, the principle of source-path-receptor is applied. This is a principle where noise mitigation is first considered at source as this is more often the most practical and cost-effective solution, and it would also provide a reduction in noise to all the surrounding receptors. Examples of mitigation at source are:
- Changes to the vertical or horizontal alignment of the road.
- Low noise road surfacing.
- Speed limits.
- Restrictions on noisy vehicle types.
DMRB LA 111 notes that, for operational mitigation, speed limits or restrictions on noisy vehicle types are not normally practical for use on motorways and all-purpose trunk roads, as they can encourage drivers to take alternative routes which can be less safe and result in higher noise levels for populations along the alternative routes.
The reduction of noise between the source and receptor is considered next as, after controlling noise at source, a reduction in the path would benefit the greatest number of receptors. A reduction in noise in the path is most likely to be achieved by placing a solid structure between the source and receptor, such as a purpose-built noise barrier. However, the use of a solid barrier would only protect receptors within around 200m of the barrier. Examples of mitigation in the path are:
- Purpose build noise barriers.
- Bunds or earth embankments.
The mitigation of noise at the receptor in the form of noise insulation of buildings is the last resort in terms of noise mitigation and is included here only to demonstrate the hierarchy of noise mitigation. Noise insulation is the last form of mitigation because it would only be of benefit to the individual receptor. In addition, providing insulation in terms of improved glazing would be ineffective if the windows of a property are open or if the individuals are outside.
Assessment of Likely Significant Effects
Construction Phase
The construction phase of the proposed scheme is likely to cause some significant adverse noise effects for some receptors and is likely to be the case for any improvement strategy. The main construction activities are likely to include the following:
- De-vegetation/site clearance.
- Earthworks/retaining walls.
- Drainage works.
- Road construction and surfacing.
- Lighting and traffic signs.
- Landscaping.
Significant adverse effects can usually be mitigated through the implementation of a Construction Environmental Mitigation Plan (CEMP). Construction phase impacts and effects will be considered in more detail at DMRB Stage 2 and 3. It is considered unlikely there would be any significant adverse effects from vibration.
Operation Phase
It has not been possible to confirm the magnitude of change in noise through calculations at this stage of assessment, and therefore the likelihood of significant effects. However, it is considered likely that with Improvement Strategies 1, 2, 4, 5 and 6, there would be significant beneficial effects from road traffic noise for receptors along the existing A75 alignment, and significant adverse effects from road traffic noise for receptors within these improvement strategies. It is considered likely that mitigation can be provided that can reduce or remove any potential significant adverse effects.
Improvement Strategy 3 involves mostly online improvements. There is the potential for significant adverse effects from road traffic noise if the improvements result in increased traffic flows or speeds. It is considered likely that mitigation can be provided that can reduce or remove any potential significant adverse effects.
The magnitude of change for route options developed within the improvement strategies will be confirmed at DMRB Stage 2 through calculation. The risk of likely significant effects is considered to be the same for all improvement strategies.
Proposed Scope of Future Assessment
Assessment should be undertaken at DMRB Stage 2 and 3 to assess potential construction noise and operational noise and vibration at a suitable level of detail proportionate to the information available at each stage.
Summary
It is likely that the construction phase would result in some temporary significant adverse effects for some noise sensitive receptors close to the construction works for any of the improvement strategies. Significant adverse effects can usually be mitigated through the implementation of a CEMP. Construction phase impacts and effects will be considered in more detail at DMRB Stage 2 and 3.
The operation phase would result in changes in road traffic noise for noise sensitive receptors, depending on their location relative to the proposed scheme. The overall effects are likely to be similar whichever improvement strategy is selected, although Improvement Strategy 3 is less likely to result in any significant beneficial effects. Operational phase impacts and effects will be considered in more detail at DMRB Stage 2 and 3.