High Speed 2 London to West Midlandsassets.hs2.org.uk/sites/default/files/inserts/booz temple hs2 lwm... · High Speed 2 London to West Midlands Appraisal of Sustainability –

High Speed 2 London to West Midlands Appraisal of Sustainability – Route Corridor and Design Speed Review

January 2012

HS2WM: London to West Midlands – Appraisal of Sustainability Route Corridors and Design Speed Review January 2012

Contents 1. INTRODUCTION ................................................................................................................................... 1

1.1. Background ............................................................................................................................... 1

1.2. Overview ................................................................................................................................... 1

1.3. Structure ................................................................................................................................... 2

1.4. Other appraisals ....................................................................................................................... 2

2. METHODOLOGY .................................................................................................................................. 3

3. AOS SUMMARY WHOLE ROUTE CORRIDOR COMPARISON ......................................................... 5

3.1. Background ............................................................................................................................... 5

3.2. Summary impacts: Consultation Route .................................................................................... 5

3.3. Summary impacts: Route 3 - Consultation Route as at 2009 (up to 360kph) .......................... 6

3.4. Summary impacts: Consultation Route redesign (up to 300kph) ............................................. 7

3.5. Summary impacts: Route 2 redesign as at 2009 (up to 360kph) ............................................. 7




4. SPEED SENSITIVITY ANALYSIS .......................................................................................................10

5. DESIGN SPEED REALIGNMENTS FOR THE CONSULTATION ROUTE ........................................11

5.1. Background .............................................................................................................................11

5.2. Study area 1: Lavender Hall Farm..........................................................................................11

5.3. Study area 2: Cubbington .......................................................................................................11

5.4. Study area 3: Chipping Warden .............................................................................................12

5.5. Study area 4: Chetwode .........................................................................................................12

5.6. Study area 5: Waddesdon ......................................................................................................12

5.7. Study area 6: Wendover .........................................................................................................12

Appendices APPENDIX 1 Assumptions and Limitations ................................................................................... 14

List of Tables Table 2-1 GIS data and source summary ........................................................................................ 4

Table 4-1 Consultation Route – Speed Sensitivity, Noise and Carbon .......................................... 10

List of Figures Figure 3-1 Whole route corridor options .......................................................................................... 6


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1. Introduction

1.1. Background 1.1.1. Following publication of High Speed Rail: Investing in Britain's Future, the Department for

Transport (DfT) undertook public consultation between 28th February 2011 and 29th July 2011. It covered the Government‟s proposed strategy for a wider network linking London, the West Midlands, Manchester and Leeds.

1.1.2. As part of this process, HS2 Ltd initiated a number of workstreams to respond to the evidence presented during consultation. Some of this work was new and a direct result of consultation responses and other work built on work previously undertaken in developing the proposals.

1.1.3. This report responds to two of the issues raised with the route selection process and route design principles, namely: The case for following existing transport corridors The maximum design speed of the route

1.1.4. This report presents the findings of the high-level Appraisals of Sustainability (AoS) that was undertaken in support of the review of route corridor options, including a summary of noise impacts associated with potential variations in line speeds.

1.2. Overview 1.2.1. A review of route corridor options was undertaken by HS2 Ltd to further consider the case

for following existing transport corridors, namely an M1 option (hereafter referred to as Route 5, in line with the Route 5 corridor developed in 2009) and a Chilterns Railways/M40 option (hereafter referred to as Route 2, in line with the Route 2 corridor developed in 2009). The study area for all route corridors for the purposes of comparative appraisal extends between Old Oak Common and Birmingham International.

1.2.2. The review of line speed was undertaken by HS2 Ltd to consider the case for adopting lower line speeds than the 400kph maximum design speed assumed for the Consultation Route, namely the same maximum design speed of High Speed 1 of 186mph (300kph), as well as a design speed of 360kph. The review therefore examined seven scenarios, namely: The Consultation Route (termed Route 3 in 2009) at a design speed of 400kph

compared with a modified alignment for design speeds of 360kph and 300kph. Route 2 at 360kph (as per the 2009 design) and 300kph (as revised for this study in

2011); and Route 5 at 360kph (as per the 2009 design) and 300kph (as revised for this study in

2011).

1.2.3. Reduced line speeds could, where existing factors permit, allow a tighter radius of curvature and a steeper line gradient. In each of the seven scenarios, the horizontal and vertical alignments were adjusted to accommodate these radius and gradient parameters, where this would allow a tighter fit within the transport corridor.

1.2.4. In addition, six study areas along the Consultation Route were identified where a change in horizontal and vertical alignment could yield local environmental benefits in comparison with the consultation scheme, while allowing for fast running of trains on other parts of the line. A parallel study was undertaken of the relative noise impacts and operational carbon footprint of trains serving the Consultation Route at 360kph, 300kph and 200kph.


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1.3. Structure 1.3.1. This report is laid out as follows:

Chapter 1 provides the background and introduction Chapter 2 summarises the general approach taken to the high level AoS Chapter 3 sets out the whole route corridor AoS findings Chapter 4 reviews the speed sensitivity tests for the Consulted Route Chapter 5 sets out the speed redesign AoS findings for the six study areas

1.4. Other appraisals 1.4.1. In addition to these studies, location-specific studies were carried out at a number of

locations along the Consultation Route. These are presented in the „Appraisal of Sustainability – Post Consultation Route Refinements’ which addresses all the route refinements examined as a result of the consultation exercise, as well as alternative locations for an infrastructure maintenance depot.


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2. Methodology

2.1.1. The AoS used an appraisal framework that was adapted from the version used for the full route as described in the published HS2 London to the West Midlands AoS report. The framework draws on the four sustainable development priorities taken from Securing the Future1, and uses a series of increasingly interrogative objectives and evaluation criteria to determine the overall sustainability performance of the options. Scheme performance for each issue is benchmarked by one or more sustainability objectives, with a range of evaluation criteria then used to describe the extent to which each objective is achieved by the option.

2.1.2. The appraisal used for the HS2 London to West Midland refinements has adopted a simplified approach that considers those issues addressed by the full AoS framework that would help distinguish the relative merits of different options. It excludes objectives and criteria where sustainability performance would vary little between options (for example operational carbon) or which are not relevant for the options in question (for example, socio-economic considerations that are pertinent only to stations).

2.1.3. Geographic Information System (GIS) data combined with a bespoke Route Appraisal Tool (RAPT), was used to assist with rapid multi-option appraisal, combining data capture with route comparison functions based on the AoS framework, of which 18 topics were considered in the simplified AoS Framework used for the appraisals in this report.

2.1.4. Information sources used for the AoS of the route refinements are set out in Table 2.1. For pertinent information on environmental designations sourced from third parties, the appraisal was reliant on a single source of ready digitised information, either in shapefile or point data format.

1 Securing the Future – Developing UK Sustainable Development Strategy 7 March 2007


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Table 2-1 GIS data and source summary

Features Classifications Feature Name (GIS Shapefile) GIS Data Source Climatic factors and adaptability

Embedded Carbon Arup Shapefile

Landscape National Parks Natural England

World Heritage Sites English Heritage

Town and cultural heritage Area of Outstanding Natural Beauty Natural England

Historic Battlefields English Heritage

Listed Buildings (Grade I, II*,II) English Heritage

Registered Parks and Gardens (Grade I,II*) Natural England

Scheduled Monuments English Heritage

Biodiversity Biogenetic Reserves N/A for these routes

EU Diploma Sites N/A for these routes

National Geoparks N/A for these routes

National Nature Reserves Natural England

Ramsar Sites Natural England

Sites of Specific Scientific Interest (SSSI) Natural England

Special Areas of Conservation (SAC) Natural England

Special Protection Areas (SPA) Natural England

Water resources Flood Zone 3 Environment Agency

Source Protection Zones 1 and 2 (SPZ) Specialist consultant

Major River Crossings N/A for these routes

Noise and vibration Residential Address Points Ordnance Survey

Community integrity Address Points Ordnance Survey

Health and well being Residential Address Points Ordnance Survey

Tranquillity (20% most tranquil area quadrants) CPRE

Soil and land resources Agricultural Land (Grade 1) Natural England

Green Belt HS2 Ltd


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3. AoS summary whole route corridor comparison

3.1. Background 3.1.1. The Consultation Route partly follows existing and disused transport corridors, such as the

Northolt rail corridor in London (following the London Underground Central Line and the Chiltern Main Line), the A413 near Amersham and Wendover and the M6 and M42 near Birmingham. Comments in consultation indicated that making greater use of existing transport corridors could minimise the environmental impact of a high speed rail proposal and potentially confine its impacts to those areas near existing transport infrastructure rather than passing currently unaffected communities and environmental features.

3.1.2. Route options have been proposed during the initial development in 2009 that adopted this approach, but HS2 Ltd did not consider these to offer the overall benefits of the proposed scheme. However, HS2 Ltd was asked to consider this further following the public consultation and reworked two previous route options specifically to closely follow existing transport corridors. These were Route 5, that partly followed the M1 corridor; and Route 2, that partly followed the corridors of the Chilterns Railway line and M40. These two options both assumed maximum line speeds of 360kph and 300kph, slower than that of the Consultation Route. These would allow for respectively greater gradients and tighter curves relative to the Consulted Route, and so enable a closer alignment alongside their associated road or railway.

3.1.3. Given the strategic nature of the study, results from the noise modelling outputs reported here have been rounded using the same conventions as the AoS of the Consultation Route. To enable a like-for-like comparison to be made between options, noise modelling results are based on an unmitigated scheme, prior to the implementation of additional mitigation.

3.1.4. The six route corridors and the Consultation Route are illustrated in Figure 3-1.

3.2. Summary impacts: Consultation Route 3.2.1. Some 14km of the Consultation Route would cross the Chilterns Area of Outstanding

Natural (AONB) in deep cutting, embankment or viaduct, with a further 6.74km crossing this feature in tunnel. Three Grade II* registered parks and gardens would be directly affected.

3.2.2. There would be direct impacts to four SSSIs (of which two could be mitigated or avoided through detailed design) and a further 14 areas of ancient woodland. Approximately 70 residential properties would be at risk of demolition, with 3,000 people experiencing annoyance from noise and 1,000 dwellings qualifying for noise insulation.

3.2.3. An estimated 350 residential properties would also lie within 100m of a tunnel section.

3.2.4. With 13.1km of the total route in tunnel, an estimated 1.5Mm3 of tunnel spoil requiring off-line disposal would be generated. The sections of the route in tunnel or cutting pass in close proximity to seven major abstractions, each supplying over 146,000m3 of drinking water per day. Further modelling of the affected aquifers would be required to establish whether this poses a potential risk.


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Figure 3-1 Whole route corridor options

3.3. Summary impacts: Route 3 - Consultation Route as at 2009 (up to 360kph) 3.3.1. The revised alignment with a slower design speed would enable the direct impacts to two

scheduled monuments to be avoided: the remains of a Roman Villa at Edgcote and a short section of the remnants of Grim‟s Ditch in Buckinghamshire. It would also reduce the number of residential properties at risk of demolition by 10 to 60, and would require one less major river diversion.

3.3.2. Conversely, a greater length of the route would affect areas of higher tranquillity2 (6.09km as compared to 4.43km for the Consultation Route). Due to an additional short section of bored tunnel in the vicinity of Chipping Warden, relative to the Consultation Route, there would be a marginal increase in the volume of tunnel spoil requiring off-line disposal at some 1.6Mm3.

3.3.3. This route would otherwise have comparable effects in terms of direct impacts on features of landscape and visual importance, ecological importance, groundwater resources, or greenhouse gas emissions and noise.

3.3.4. There would also be no marked difference in terms of the numbers of people experiencing adverse noise impacts, the numbers of dwellings qualifying for noise insulation, or the numbers of dwellings within 100m of a tunnel section.

2 Tranquillity determined by CPRE mapped squares each with a different measure of tranquillity.


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3.4. Summary impacts: Consultation Route redesign up to 300kph 3.4.1. The slower design speeds would result in a substantial reduction in the numbers of people

experiencing noise annoyance at 1,900 people compared with 3,000 people for the Consultation Route. However, there is only a small reduction in the number of dwellings qualifying for noise insulation. This route would also result in a small reduction in the number of residential properties at risk of demolition to 60 compared with 70 for the Consultation Route. The lower line speeds would also result in less operational energy demand and associated carbon emissions of about 14MtCO2e3.

3.4.2. Conversely, the alignment would still have direct impacts on two scheduled monuments: the Roman Villa at Edgcote and a short section of Grim‟s Ditch in Buckinghamshire. It would also result in two major river diversions.

3.4.3. This option would otherwise have comparable impacts to the Consultation Route in terms of tunnel spoil generated and the numbers of dwellings within 100m of a tunnel section.

3.5. Summary impacts: Route 2 redesign as at 2009 (up to 360kph) 3.5.1. Route 2 would follow the Consultation Route from Euston to the Colne Valley, but would

then continue alongside the Chiltern Railways Line. The route would be tunnelled beneath Gerrards Cross, surfacing to pass through the area around Seer Green before entering a seven and a half mile tunnel under both Beaconsfield and High Wycombe. It would surface again within the Chilterns AONB near Bradenham, continuing across open countryside to avoid impacts to Princes Risborough. Once beyond the AONB the route would broadly follow the Chiltern Railways corridor to Bicester. Following the M40 corridor, it would run close to Banbury, but still deviate away from the motorway for significant stretches because of the tighter curvature of the road. There would be a need for tunnelling or viaducts throughout this section to avoid motorway junctions.

3.5.2. A key benefit of this route is that it would cross the Chilterns AONB at a narrower point than the Consultation Route and have a shorter section of surface route across it (5.55km). A 30m section of the south-west boundary of the Grade I registered park and garden at Farnborough Hall would be affected, but on balance, the impacts to registered parks and gardens would be lower.

3.5.3. The route would perform marginally better in terms of ecology with fewer direct impacts on SSSIs and substantially less impact to important habitats, including ancient woodland. However, the proximity of this route to Chiltern Beechwoods Special Area of Conservation (SAC) (250m) would present a project risk and could trigger Appropriate Assessment under the Habitat Regulations.

3.5.4. Fewer residential properties would be at risk of demolition, one community would be at risk of isolation and 18 dwellings being potentially affected. This compares with the Consultation Route which results in eight dwellings at risk of isolation.

3.5.5. About 300 fewer people would experience noise annoyance compared with the Consultation Route. However, about 110 more dwellings would qualify for noise insulation and the need to tunnel would mean that an estimated 3,900 properties would fall within 100m of tunnel sections potentially resulting in greater track mitigation. With over 36km of the total route in tunnel there would be a significant increase in the volume of tunnel spoil requiring off-line disposal at about 4Mm3.

3.6. Summary impacts: Route 2 redesign as at 2011 (up to 300kph) 3.6.1. As with Route 2 (2009), this option would cross the Chilterns AONB at a narrower point and

have a shorter section of surface route across (5.73km). There would also be less direct impact to SSSIs and substantially less impact to ancient woodland. At a distance of 750m from Chilterns Beechwoods SAC, the route is less likely to trigger Appropriate Assessment under the Habitat Regulations. The route would also have significantly less impact on

3 Million tonnes of carbon dioxide (or an amount of carbon equivalent to this).


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groundwater resources, crossing 40% less Grade 1 Source Protection Zones (SPZ1) in cut or tunnel at 2.82km compared to 4.99km for the Consultation Route. It would also pass in close proximity to only one major licensed abstraction, supplying over 146,000m3 of drinking water per day at Ickenham as compared to 7 major abstractions for the Consultation Route, although further modelling would be required to establish whether there is any risk to the aquifer.

3.6.2. 50 properties would be at risk of demolition, which is fewer than the Consultation Route. This would result in three communities being at risk of isolation, potentially affecting 106 dwellings.

3.6.3. Some 880 fewer people would experience noise annoyance and approximately 950 dwellings would qualify for noise insulation compared to approximately 1,000 for the Consultation Route. The lower line speeds would also result in lower operational energy demand and associated carbon emissions, at an estimated 14.5MtCO2e, which is less than the Consultation Route.

3.6.4. The need to tunnel would mean that an estimated 3,900 properties would fall within 100m of tunnel sections and this is likely to result in greater track mitigation, than the consultation route.

3.6.5. A significant disadvantage would be the potential impacts on the scheduled monument of Warwick Castle and the setting of its Grade I Registered Park and Garden, which would be crossed at its southern boundary on a 140m length of viaduct. Many more listed structures and scheduled monuments would be indirectly affected, but one less scheduled monument would be directly affected. This route would potentially affect the setting of 10 Grade II* listed structures as compared to six for the Consultation Route and two Grade II* registered parks and gardens as compared to none for the Consultation Route.

3.6.6. Over 26km of the total route would be in tunnel, resulting in a substantially greater volume of tunnel spoil requiring off-line disposal at about 3Mm3.

3.7. Summary impacts: Route 5 redesign as at 2009 (up to 360kph) 3.7.1. Route 5 follows the Consultation Route from Euston to Old Oak Common. It would tunnel

some 16 miles from Old Oak Common to emerge north of the M25 close to the M1. It would pass through a gap in the Chilterns AONB, passing in tunnel under the western edge of Luton. Emerging north of Luton, the route would then travel at ground level past Milton Keynes and Northampton, before curving west to follow the M45/A45 past Rugby, and re-joining the Consultation Route near Kenilworth.

3.7.2. This route would avoid direct impacts to the Chilterns AONB. Additionally impacts on registered parks and gardens would be marginally lower, with one Grade II* and one Grade II feature affected, both of which could be avoided through detailed design. This route also performs well in terms of noise impacts, with substantially fewer people (approximately 1,000 in total) potentially experiencing noise annoyance and about 650 fewer dwellings potentially qualifying for noise insulation.

3.7.3. The route would pass in close proximity to two very major abstractions, each supplying over 263,500m3 of drinking water per day, but substantially less of the route would cross the aquifers of both good yield and good quality in tunnel or cutting (14.08km) as compared to the Consultation Route (34.79km).

3.7.4. A key disadvantage would be the potential fragmentation of Salcey Forest SSSI with over 1.25km of the site severed at a midway point.

3.7.5. Over 200 dwellings would be at risk of demolition, including potential clusters of demolitions at Thurlaston, Caddington, Slip End, Whilton Lodge and Pepperstock. Twelve communities would be at risk of isolation, and a further two would be at risk of severance, potentially affecting 143 and 166 dwellings respectively.

3.7.6. The need to tunnel would mean that an estimated 5,900 properties would fall within 100m of tunnel sections, a number substantially higher than for the Consultation Route (350


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properties), with over 30km of the total route in tunnel. There would also be a significant increase in the volume of tunnel spoil requiring off-line disposal at about 3.4Mm3.

3.8. Summary impacts: Route 5 redesign as at 2011 (up to 300kph) 3.8.1. As with Route 5 (2009), this route would avoid direct impacts to the Chilterns AONB. While

impacts to scheduled monuments would be broadly comparable to Route 5 (2009), this route would avoid impacts to registered parks and gardens. It would also have significantly lower impacts on nationally protected ecological sites, affecting only one SSSI (River Blythe) on viaduct, and would have lower direct impacts on BAP habitats and ancient woodland.

3.8.2. This route would also perform well in terms of noise impacts, with substantially fewer people (approximately 970) potentially experiencing noise annoyance and approximately 700 fewer dwellings potentially qualifying for noise insulation. The costs of mitigating the potential effects of vibration on the estimated 6,400 dwellings within 100m of a tunnel section would be greater than for the consultation route. With over 29km of the total route in tunnel, there would also be a significant increase in the volume of tunnel spoil requiring off-line disposal at about 3.3Mm3.

3.8.3. In addition, the lower line speeds would result in less operational energy demands and associated carbon emissions at some 14.8MtCO2e.

3.8.4. A key disadvantage of the route would be the significant increase in the number of residential properties at risk of demolition (150 properties), including clusters at Thurlaston, Blakelands, Milton Keynes, Hartwell and Pepperstock. This route would also result in 4 communities being at risk of isolation, potentially affecting 61 dwellings, and a further one at risk of severance, potentially affecting 30 dwellings.


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4. Speed sensitivity analysis

4.1.1. A concern raised at consultation was that the assumed operating speeds for HS2 might be excessive and that impacts could be reduced through lower running speeds, both directly through slower and quieter trains with lower energy demands and indirectly through allowance of tighter radius curves to avoid sensitive locations. The latter has been addressed generically in the previous chapter.

4.1.2. In general it shows that lower speed results in lower noise and carbon impacts. However, the significance of this should be seen in the context of recent route refinement work and design improvements.

4.1.3. The airborne noise appraisal of the Speed Sensitivity Analysis has been carried out using the same method as the Consultation Route as presented in the HS2 London to West Midlands: Appraisal of Sustainability (AoS). The Consultation Route with 360kph maximum speed assumes a 400kph maximum design speed, and is identical to the scenario presented in the AoS. The operational speed has been varied to 300kph and 200kph for these additional scenarios. However all other assumptions including vertical and horizontal alignment and barrier placement for the "with additional indicative mitigation" scenario are identical to those presented in the AoS.

Table 4-1- Consultation Route – Speed Sensitivity, Noise and Carbon Consultation Route/Refined Route

Noise Carbon

Change in population annoyed by operational noise

Present Value Benefits

Number of properties potentially qualifying for noise insulation

Operational carbon emissions (train trips only) (MtCO2e)

Unmitigated

@ 360kph ~4300 -£220,000,000 <1400 ~18.5

@ 300kph ~3300 -£170,000,000 ~1300 ~16

@ 200kph ~1400 -£76,000,000 ~1100 NA

Mitigated

@ 360kph ~850 -£41,000,000 <150 ~18.5

@ 300kph ~490 -£25,000,000 <90 ~16

@ 200kph ~170 -£10,000,000 <70 NA


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5. Design speed realignments for the Consultation Route

5.1. Background 5.1.1. HS2 has been designed with a maximum line speed capability of up to 250mph (400kph).

The maximum operating speed at opening would be 225mph (360kph), with services timetabled assuming an actual operating speed of around 205mph (330kph). The Consultation Route already contains large sections where a lower design speed is assumed in order to minimise impacts on people or to adhere to running or design parameters for example, within tunnels and across junctions. Only 68 miles of the route have been specified for a maximum 250mph speed with many areas of the route already having speed limitations.

5.1.2. As a consequence, the scope to further reduce impacts by lowering the design speed is limited to a smaller part of the route, between Amersham and the Interchange Station near to the NEC at Birmingham, around 110km of route. HS2 Ltd has therefore considered sections where further line speed reductions (to 300kph and 360kph) could be adopted at further specified locations to allow for local modification of the alignment and so potentially reduce environmental impacts.

5.1.3. The review of the Consultation Route using features and parameters described in the AoS Report for London to West Midlands identified a total of nine possible areas where impacts might be avoided or where other benefits result. Of the nine locations considered, three would result in no overall improvements through alignment change, either because the benefit would not be realised or because change would have a consequential effect on environmental features or communities further along the line of route.

5.1.4. The implications for these changes at the other six locations are reported below.

5.2. Study area 1: Lavender Hall Farm 5.2.1. A 360kph route would follow a slightly different alignment from the Consultation Route,

passing further from Balsall Common. It would avoid the demolition of a Grade II listed structure and would have a lower impact on the setting of the Grade II* listed Lavender Hall Farm. It would be marginally better in terms of embedded carbon, soil and land resources and would reduce the risk of residential demolitions by one property. Although further from Balsall Common, there would be very little difference in noise annoyance, although up to 10 fewer people would qualify for noise insulation.

5.3. Study area 2: Cubbington 5.3.1. Both the 300kph and 360kph realigned route would diverge from the Consultation Route

between a point east of the National Agricultural Centre at Stoneleigh and a point near the Fosse Way (Roman Road). Both routes would pass further from Weston under Weatherly and Hunningham, but closer to Cubbington and Offchurch, and on embankment.

5.3.2. Both routes would perform significantly better than the Consultation Route in respect of ecology, potentially avoiding direct impacts to South Cubbington Wood Biodiversity Action Plan (BAP) habitat and ancient woodland. Conversely, both realignments would result in a significant increase in the length of route most at risk of flooding, owing to the greater length of flood plain affected. Noise impacts would change with the 300kph and 360kph alignments would each result in up to 10 more properties potentially qualifying for noise insulation. However, the 300kph realignment would result in a reduction of 10 in the number of people likely to be annoyed by noise there would be no change for the 360kph alignment.


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5.4. Study area 3: Chipping Warden 5.4.1. A 360kph realigned route would diverge from the Consultation Route between Aston-le-

Walls and the Great River Ouse. It would pass further from Turweston, Greatworth and Thorpe Mandeville, but closer to Whitfield and Culworth, with generally less cutting. This route would perform better for cultural heritage by avoiding the Roman Villa at Edgcote, a scheduled monument and potentially the historical battlefield at Edgcote Moor, although the site of this has not been fully defined. The route would avoid impacts to the BAP habitat and ancient woodland at Halse Corpse and would result in fewer properties being at risk of demolition. It would also affect less high quality farmland. Noise annoyance is likely to affect 10 fewer people, and up to 10 fewer properties would potentially qualify for noise insulation.

5.5. Study area 4: Chetwode 5.5.1. A small change in alignment for both the 300kph and 360kph realigned routes would take it

further from Twyford, although with a reduced length of cutting. Both options perform better than the Consultation Route in respect of community integrity, each requiring four fewer residential demolitions and both would have lower impacts on the settings of listed structures. The 300kph route would have the fewest noise impacts with a reduction by some 50 people likely to be affected by noise annoyance (10 fewer for the 360kph route) and up to 20 fewer dwellings potentially qualifying for noise insulation (up to 10 fewer for the 360kph route). Conversely, the Consultation Route would be marginally better than both proposed realignments in terms of flood risk.

5.6. Study area 5: Waddesdon 5.6.1. The 360kph realignment would pass further from Waddesdon, but with less cutting and

more embankment. The proposed realignment would perform moderately better than the Consultation Route in respect of cultural heritage and marginally better in terms of landscape and townscape. Conversely, the realigned route would result in a marginal increase in noise impacts, with a greater number of isolated and scattered dwellings to the north-east of the route being brought into closer proximity to the route and the higher elevation offsetting the greater distance from Waddesdon: 10 more noise annoyance impacts are predicted and up to five more dwellings would qualify for noise insulation. It would also put one of the industrial buildings associated with Buckinghamshire Railway Centre at risk of demolition.

5.6.2. The 300kph realignment would pass further from Waddesdon but slightly closer to Quainton, although at a lower alignment. This realigned route would perform substantially better than the Consultation Route in respect of noise as a result of reduced noise arising from a combination of reduced line speeds and increased distance from the realigned route. Some 280 fewer people are likely to be affected by noise annoyance, although there is little change in noise insulation requirements. It would perform moderately better in terms of impacts to landscape and townscape and marginally better in terms of cultural heritage. The 300kph proposed realignment would still put one of the industrial buildings associated with Buckinghamshire Railway Centre at risk of demolition.

5.7. Study area 6: Wendover 5.7.1. The 360kph realigned route diverges from the Consultation Route between a point west of

Wendover (Nash Lee Road) and just before the green tunnel at Frith Hill Road. This moves it further from Wendover, but on a higher embankment; closer to properties on London Road; and further from Wendover Dean and in more cutting. It would perform better than the Consultation Route in respect of cultural heritage and community integrity. It would avoid impacts to Grim‟s Ditch Scheduled Monument and avoid the demolition of Wendover Cricket Club‟s sports pavilion and ground at Ellesborough Road. However, the shift in alignment in the vicinity of Wendover would take the route out of the existing transport corridor, therefore making it a more distinct feature in the landscape. Any noise benefits achieved through increased distance from Wendover would also be largely offset by the


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alignment being 3m to 5m higher on embankment through this section. However approximately 30 fewer people would likely to be affected by noise annoyance and up to 10 fewer properties would potentially qualify for noise insulation.


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APPENDIX 1 Assumptions and Limitations

The AoS has been carried out at a higher level than was undertaken for the Consultation Route and the findings are not directly comparable in some instances. In particular:

SPOIL CALCULATIONS

The appraisal assumed a standard external tunnel diameter of 8.5m for the twin bore tunnels and a lining thickness of 0.5m to calculate the volumes of spoil likely to be generated.

DEMOLITIONS

Demolitions were identified on GIS using a standard 50m buffer for rural areas and a 25m buffer for urban areas.

Demolition numbers in this report may differ from figures cited in the engineering report, which has been based on earthworks footprints.

NOISE

Route Corridor Comparison The airborne noise appraisal of the Route Corridor Comparison has been carried out using the same method as the Consultation Route as presented in the HS2 London to West Midlands: Appraisal of Sustainability, however updates have been made due to the lower level of geometric detail provided for the alternative route corridors. All route options (including the Consultation Route) appraised in the Route Corridor Comparison have been appraised using the same method.

The key assumptions and limitations of the noise model are therefore also largely the same, other than changed assumptions regarding the maximum operational speed. Results are based on the operational service patterns for the London to West Midlands High Speed Rail Network (i.e. without “Y”). Only results without additional mitigation (the unmitigated scheme) have been generated, as these are used to provide the best like for like comparison of the routes.

Additional updates to the model process, assumptions and limitations of the Route Corridor Comparison are detailed below.

The HS2 Route Corridor alignments were provided as a three dimensional shapefile. Earthworks shapefiles were not able to be provided for all options; therefore these were generated automatically in CadnaA with a slope of 2:1.

All dwellings (within 300m and outside of 300m) from route centreline have been spatially located from postal address point data and grouped to 50m x 50m grid squares.

Speed Sensitivity Analysis The airborne noise appraisal of the Speed Sensitivity Analysis has been carried out using the same method as the Consultation Route as presented in the HS2 London to West Midlands: Appraisal of Sustainability.

Documents

High Speed 2 London to West Midlandsassets.hs2.org.uk/sites/default/files/inserts/booz temple hs2 lwm... · High Speed 2 London to West Midlands Appraisal of Sustainability –