17 Disruption Due to Construction 17.1 Introduction 17.2 Approach and Methods 17.3 Baseline Conditions 17.4 Potential Impacts 17.5 Potential Mitigation 17.6 Summary of Route Corridor Options Assessment 17.7 Scope of Stage 3 Assessment 17.8 References
17 Disruption Due to Construction
17.1 Introduction
17.1.1 This chapter provides an initial assessment of the potential disruption impacts during to construction of the Forth Replacement Crossing.
17.1.2 As defined by DMRB, ‘disruption due to construction’ is a term which covers the effects on people, properties and the natural environment that can occur between the start of pre-construction works and the end of the contract maintenance period. Potential disruption due to construction impacts can include nuisance arising from noise, vibration, dust, and loss of amenity. Construction activities can also impact routes utilised by different types of users including vehicular, pedestrian and cyclist. There is also the potential for impacts on the natural environment through disturbance to wildlife, pollution of watercourses or by storage of materials on ecologically valuable land.
17.1.3 For the purposes of Stage 2, the objective of the assessment is to identify factors and effects associated with disruption due to construction to enable refinement of the route corridor options. This assessment contains the following:
- the estimated number of properties within 100m of each northern and southern route corridor option, specifically highlighting any properties which are particularly sensitive to disruption (e.g. schools, hospitals, aged person homes and libraries);
- identification of any areas or features of ecological or cultural heritage value within 100m of the route corridor options which may require protection from adverse construction impacts;
- an estimation and comparison between route corridor options of the approximate quantities of excavation and fill material requirements for earthworks;
- identification of potential impacts resulting from the construction of the Forth Replacement Crossing in terms of agricultural land use, landscape, visual, non-motorised users (NMUs) and vehicle travellers; and
- potential mitigation measures to address these impacts.
17.1.4 At Stage 2 detailed information on construction programme and methods are not available and as such potential impacts and mitigation in this chapter are described generally. However, qualitative comparative assessment of the route corridor options is provided in Section 17.6 (Summary of Route Corridor Options Assessment).
17.2 Approach and Methods
17.2.1 The Stage 2 assessment has been undertaken in accordance with the guidelines outlined in DMRB Volume 11, Section 3, Part 3 (The Highways Agency et al., 1994).
17.2.2 For the purposes of Stage 2 assessment, construction impacts are considered temporary and occur either prior to (e.g. diversion of utilities) or during construction. Operational impacts are considered as long term or permanent impacts. As indicated in paragraph 17.1.3, this chapter focuses on disruption due to construction in terms of land use, air quality, landscape, visual, NMUs (i.e. pedestrians, equestrians, cyclists and community effects) and vehicle travellers. Construction impacts in relation to other Stage 2 environmental parameters are provided within the potential impacts sections of respective chapters, due to construction impacts and operational impacts being interlinked or due to the requirement to interpret detailed and/or technical baseline or impact data. Compliance with policies and plans (Chapter 18) is not considered likely to be affected by construction works and is therefore omitted from assessment.
17.2.3 In accordance with DMRB, this chapter also provides an estimate of the number of areas or features of ecological or cultural heritage value within 100m of each route corridor option, although this is provided as baseline context only, with construction impacts considered in sections 9.4 and 12.4 (potential impacts) of the respective chapters for the reasons stated above.
17.2.4 The Jacobs Arup GIS database uses Ordnance Survey (OS) information and was used to identify numbers and types of properties within 100m of northern and southern route corridor options. An estimate of the volume of excavated and fill quantities required for each corridor option was also calculated. This enabled a preliminary assessment of the potential disruption resulting from earthworks construction to be undertaken, based on the assumption that, all other aspects being equal, the more earthworks required and the greater the quantity of material to be excavated and filled, the longer potentially disruptive works are likely to take to complete, and the greater the cumulative potential for disruption impacts.
Limitations to Assessment
17.2.5 As the precise details of the construction programme and approach have not yet been determined, assessment has been made qualitatively, except where reliable quantitative data were available.
17.2.6 Potential disruption impacts arising from construction of the proposed replacement bridge (e.g. commercial and recreational use of and navigation on the Firth of Forth) are common to all route corridor options and as such have not been assessed at this stage.
17.2.7 The number of cultural heritage and ecological designations within 100m of the options is provided in Section 17.3 (Baseline Conditions). It should be noted that counts for each route corridor option should not be summed, as certain features are subject to more than one designation or designations relate to more then one distinct area. Examples are as follows:
- Firth of Forth SPA is also notified as a SSSI and Ramsar site; and
- Ferry Hills SSSI is a single designation (and recorded as such in Section 17.3) but has several geographically distinct component areas.
17.3 Baseline Conditions
17.3.1 The purpose of this section is to outline key sensitivities within 100m of the route corridor options and also provide an indication of the likely earthwork requirements. Detailed baseline information concerning NMUs, land use, landscape, visual and vehicle travellers is presented in the baseline sections of Chapter 6 (Land Use), Chapter 10 (Landscape), Chapter 11 (Visual) and Chapter 16 (Vehicle Travellers) and not restated here.
Proximity to Properties
17.3.2 Tables 17.1 and 17.2 provide an estimate of the number and type of properties within 100m of each of the northern and southern route corridor options (inclusive of any properties abutting the northern and southern landfalls of the proposed replacement bridge).
17.3.3 There are no hospitals, aged persons homes, churches, libraries, or medical clinics within 100m of any of the northern or southern route corridor options.
Northern Route Corridor Options
Table 17.1: Estimated Number of Properties within 100m of North Corridor Options 1 and 2
| Property Type |
North Corridor Option 1 |
North Corridor Option 2 |
|---|---|---|
Residential |
413 |
357 |
Commercial |
35 |
34 |
School |
1 |
1 |
Southern Route Corridor Options
Table 17.2: Estimated Number of Properties within 100m of South Corridor Options 1 and 2
| Property Type |
South Corridor Option 1 |
South Corridor Option 2 |
|---|---|---|
Residential |
344 |
337 |
Commercial |
6 |
7 |
School |
None |
1 |
Cultural Heritage
17.3.4 There are a number of sites of cultural heritage value in close proximity to northern and southern route corridor options. Tables 17.3 to 17.4 provide a summary of the numbers within 100m.
Northern Route Corridor Options
Table 17.3: Estimated Number Cultural Heritage Sites within 100m of North Corridor Options 1 and 2
| Cultural Heritage Designation |
North Corridor Option 1 |
North Corridor Option 2 |
|
|---|---|---|---|
Scheduled Ancient Monuments |
1 |
None |
|
Conservation Areas |
None |
None |
|
Listed Buildings |
Category A |
None |
None |
Category B |
4 |
6 |
|
Category C |
1 |
None |
|
Southern Route Corridor Options
Table 17.4: Estimated Number of Cultural Heritage Sites within 100m of South Corridor Options 1 and 2
| Cultural Heritage Designation |
North Corridor Option 1 |
North Corridor Option 2 |
|
|---|---|---|---|
Scheduled Ancient Monuments |
None |
None |
|
Conservation Areas |
None |
1 |
|
Listed Buildings |
Category A |
None |
None |
Category B |
None |
None |
|
Category C |
1 |
2 |
|
Ecological Designations
17.3.5 There are a number of designated sites of ecological value in close proximity to the northern and southern route corridor options. Tables 17.5 to 17.6 provide a summary of the numbers of designated sites within 100m.
Northern Route Corridor Options
Table 17.5: Estimated Number of Ecological Designations within 100m of North Corridor Options 1 and 2
| Ecological Designation |
North Corridor Option 1 |
North Corridor Option 2 |
|---|---|---|
Ramsar Sites |
1 |
1 |
Special Protection Areas |
1 |
1 |
Sites of Special Scientific Interest |
3 |
3 |
Sites of Importance for Nature Conservation |
None |
None |
Wildlife Sites |
None |
None |
Ancient Woodland (of Semi Natural Origin) |
None |
None |
Long-Established Woodland (of Plantation Origin) |
4 |
3 |
Southern Route Corridor Options
Table 17.6: Estimated Number of Ecological Designations within 100m of South Corridor Options 1 and 2
| Ecological Designation |
South Corridor Option 1 |
South Corridor Option 2 |
|---|---|---|
Ramsar Sites |
None |
None |
Special Protection Areas |
None |
None |
Sites of Special Scientific Interest |
None |
None |
Sites of Importance for Nature Conservation |
4 |
4 |
Wildlife Sites |
2 |
2 |
Ancient Woodland (of Semi Natural Origin) |
1 |
1 |
Long-Established Woodland (of Plantation Origin) |
4 |
8 |
Earthworks Requirement (Cut and Fill Volume Estimates)
17.3.6 For all northern and southern route corridor options, the estimated amount of fill material required for engineering and landscape earthworks exceeds the amount of reusable material that will be excavated in the course of engineering works, as shown in Table 17.7. This may mean that additional fill material will be outsourced from locations away from construction sites (e.g. from quarries), and this could potentially exacerbate disruption impacts through transport and haulage to site requirements. Note that the specific locations of borrow sites have not been identified at this stage, and local planning authorities have not been contacted in this regard.
Table 17.7: Estimated Earthworks Requirements for All Route Corridor Options
| Route Corridor Option |
Excavation Quantity (m3) |
Fill Quantity (m3) |
Total Borrow (m3) |
|---|---|---|---|
North Corridor Option 1 |
534,219 |
1,583,605 |
1,049,386 |
North Corridor Option 2 |
934,291 |
1,285,048 |
350,757 |
South Corridor Option 1 |
770,306 |
1,057,908 |
287,602 |
South Corridor Option 2 |
2,349,889 |
2,792,063 |
442,174 |
17.4 Potential Impacts
17.4.1 Potential impacts of the route corridor options on land use (agricultural only), landscape and visual, air quality, NMUs and vehicle travellers are detailed below. Earthworks requirements are also considered. It should be noted that potential impacts identified are prior to the implementation of mitigation.
Land Use
- damage to land (e.g. movement of machinery, storage of materials, access routes);
- temporary access restrictions to properties including businesses and farm buildings;
- reduced soil quality, which can cause long term damage including reduced agricultural capability of the soils;
- disruption to existing drainage system and changes in flood risk; and
- temporary severance of land causing disruption to farming practices, including preventing movement of machinery or livestock.
Landscape and Visual
- vehicles moving machinery and materials to and from the site;
- on-site machinery including heavy excavators, earth moving plant, concrete batching plant, pile drivers, cranes etc;
- exposed bare earth over the extent of the proposed works;
- structures, earthworks, road surfacing and ancillary construction works;
- temporary site compound areas including site accommodation and parking;
- temporary soil storage heaps and construction materials stockpiles;
- lighting associated with night-time working and site accommodation; and
- demolition operations.
Air Quality
- soiling of cars, windows, painted surfaces etc by deposited dust;
- damage to vegetation from deposited dust;
- damage to crops or commercial operations from deposited dust; and
- health effects from exposure to air pollution.
NMUs
- restriction or prevention of access in areas used by the community;
- diversion or restriction of routes such as footpaths and cycleways; and
- noise, dust and reduction in visual amenity.
Vehicle Travellers
- delays to journeys due to restricted traffic flows;
- increase to driver stress due to road diversions and other temporary measures; and
- negative impacts on drivers view from the road due to construction works.
17.5 Potential Mitigation
17.5.1 Detailed mitigation will be developed as part of DMRB Stage 3 assessment when additional construction information is known and can be assessed in further detail. Typical mitigation measures are provided below.
Land Use
- restriction of construction activities to a working corridor;
- reduction of temporary land loss to agriculture through construction programming, consultation with land interests, and reinstatement of agricultural land post construction;
- maintenance of agricultural land capability through best practice techniques for handling and storage of soils;
- avoidance of flood issues through pre-construction drainage works and reinstatement/provision of new drainage as required; and
- maintenance of vehicular access to farm buildings.
Landscape and Visual
- programming of works to reduce disruption, including keeping the construction programme to the minimum practicable time;
- avoidance of night-time working where possible. Where necessary, directed lighting used to minimise light pollution/glare;
- sensitive locating of site compounds to minimise their landscape and visual impact; and
- construction sites to be kept tidy (e.g. free of litter and debris).
Air Quality
- careful storage of materials including topsoil, movement of plant and other activities during construction away from potentially sensitive receptors;
- maintaining equipment as per manufacturers specifications to reduce emissions;
- switching off machinery and vehicles when not in use;
- covering trucks transporting dust-reducing material leaving or entering the construction site; and
- conforming with all relevant local authority requirements for dust control.
NMUs
- programming to reduce the length of closures or restrictions of access;
- routes used by pedestrians and others maintained or re-routed where possible;
- any closure or re-routing of routes used by pedestrians and others agreed in advance with the local Councils;
- minimise air quality and noise impacts as far as practicable; and
- keep the local community informed with regard to construction activities.
Vehicle Travellers
- scheduling where possible to minimise disruption to the road traffic, including the timing of works vehicles using public roads and delivery/removal of site materials;
- minimise import/export of material;
- avoidance of road closures where possible;
- temporary traffic management to minimise disruption and delays; and
- road diversions clearly indicated with road markings and signage as appropriate.
17.6 Summary of Route Corridor Options Assessment
17.6.1 It is anticipated that mitigation measures identified can be implemented to reduce potential impacts. However, disruption during construction will be unavoidable on such a large infrastructure project, and the following section provides a comparison of route corridor options in terms of the likely extent of such disruption.
Northern Route Corridor Options
17.6.2 In terms of earthworks balance, the anticipated fill requirements for North Corridor Options 1 and 2 are broadly similar however, the excavation requirement for North Corridor Option 1 is expected to be 43% lower than for North Corridor Option 2. As a result, the level of borrow requirements would be approximately three times higher for North Corridor Option 1, requiring the movement of 698,629m2 more material than North Corridor Option 2. Consequently, potential for disruption impacts from earthworks is likely to be considerably more significant for North Corridor Option 1.
17.6.3 North Corridor Option 1 is within 100m of slightly more properties overall than North Corridor Option 2. The proportional difference between the overall numbers of properties within 100m potentially affected is approximately 15% greater for North Corridor Option 1 than North Corridor Option 2. This presents a slight increase in potential for impacts to aspects such as landscape and visual amenity and air quality.
17.6.4 Total agricultural land take estimate for North Corridor Option 1 is 7.6ha compared to 9.5ha for North Corridor Option 2, although severance of land is also likely to be comparable. Some potential severance issues have been identified for businesses within Belleknowes Industrial Estate for North Corridor Option 2. Overall, North Corridor Option 2 is expected to have a higher potential for temporary impacts on land use.
17.6.5 North Corridor Option 1 would cross fewer routes identified as used by pedestrians and there is therefore less potential for disruption to NMUs than for North Corridor Option 2. However, in terms of vehicle travellers, North Corridor Option 2 has less potential for disruption as it is largely offline so there would be less disruption on the existing carriageway.
17.6.6 Overall as North Corridor Option 1 is mainly online, the magnitude of disruption in relation to earth movements and traffic interruptions would be comparatively high. The number of properties within close proximity of North Corridor Option 1 is also comparatively high. Land use impacts however would be reduced compared to North Corridor Option 2 due to less land take.
Southern Route Corridor Options
17.6.7 In terms of earthworks balance, South Corridor Option 2 would require the movement of approximately 54% (154,572m2) more material than South Corridor Option 1. Consequently, potential for disruption impacts from earthworks is likely to be more significant for South Corridor Option 2.
17.6.8 The number of properties within 100m of South Corridor Option 1 is marginally (1.5%) greater than South Corridor Option 2. Although the number of properties within 100m is similar, South Corridor Option 2 is within 100m of Dalmeny Primary School and impacts on areas of countryside with properties that are more likely to be sensitive to changes in aspects such as landscape and visual amenity and air quality.
17.6.9 Total agricultural land take estimate for South Corridor Option 2 is 56.4ha compared to 30.8ha for South Corridor Option 1, and severance of land is also likely to be higher. On this basis, South Corridor Option 2 is also expected to have a higher potential for temporary impacts on agricultural land use.
17.6.10 Both southern route corridor options are considered similar in terms of potential for disruption to vehicle travellers during construction. However, South Corridor Option 1 would cross fewer routes identified as being used by pedestrians than South Corridor Option 2.
17.6.11 South Corridor Option 2 would require a higher level of junction/road construction and overall the magnitude of disruption in relation to earth movements and land take requirements would be comparatively greater. Although the number of receptors within close proximity of South Corridor Option 1 is slightly higher than for South Corridor Option 2, properties within 100m of South Corridor Option 2 may be more sensitive to change due to their rural location.
17.7 Scope of Stage 3 Assessment
17.7.1 The Stage 3 assessment of disruption due to construction will follow the approach set out in DMRB, Volume 11, Section 3, Part 3 (The Highways Agency et al. 1994) and will include the following steps:
- verification of the properties identified within 100m of the route at Stage 2;
- verification of the ecology and cultural heritage features identified within 100m of the route at Stage 2;
- description of any construction operations with potentially significant impacts;
- assessment of the extent of potential impacts arising during construction, taking into account proposed mitigation;
- estimate of the likely quantities of surplus/borrow material associated with the scheme and details of the size and locations of borrow pits and disposal sites where appropriate; and
- identification of mitigation as appropriate.
17.8 References
The Highways Agency et al. (1994). DMRB Volume 11 Disruption Due to Construction, Section 3, Part 3, August 1994. The Highways Agency, Scottish Executive Development Department, The National Assembly for Wales and The Department of Regional Development Northern Ireland