CHAPTER 13 – TRANSPORT ASSESSMENT Introduction … · · 2016-04-28CHAPTER 13 – TRANSPORT...

MYG Chapter 13: Transport Assessment

Mynydd y Gwynt Wind Farm: Environmental Statement July 2014

CHAPTER 13 – TRANSPORT ASSESSMENT

Introduction

13.1 Mynydd y Gwynt Limited commissioned WYG, Transport Planning Specialists, to undertake a Transport Assessment (“TA”) of the transport issues associated with the development of the proposed 27 turbine Mynydd y Gwynt Wind Farm over approximately 584 hectares of the Sweet Lamb Rally Complex, at Y Foel, west of Llangurig, Powys.

13.2 This assessment has been prepared in accordance with instructions from Mynydd y Gwynt Limited on the above project details. No liability is accepted for the use of all or part of this report by third parties.

13.3 It is the responsibility of the wind farm developer to ensure that the access routes to the site are fit for purpose and that appropriate consideration for all road users has been made in accordance with the relevant health and safety legislation and ruling transport requirements at the time the project commences on site.

13.4 WYG has accordingly reviewed the transport issues associated with the development along with the route for abnormal loads from the strategic road network to the development site. The report identifies the key transport and access points and issues associated with the development of the site that may require remedial works to accommodate the predicted loads. The detailed design of these remedial works, however, is beyond the scope of this report.

Proposed Wind Farm

Site Description and Location

13.5 The proposed development is for a 27 turbine wind farm on an area of 584 hectares of land at the Sweet Lamb Rally Complex, at Y Foel, near Llangurig, Powys. The site lies approximately 25km east of Aberystwyth and 8km west of Llangurig and the location is illustrated in Figure 1.1.

13.6 Loads will access the site from the strategic road network by way of the A470 north, A470 south and A44 west.

13.7 Access to the development site will be taken from a modified junction with A44(T) at the southern boundary of the site. The existing junction would be modified to form the new junction. An indicative design for the proposed site access is shown in Figure 6.1.

13.8 There is an extensive track network within the site used by the rally complex which provides motor rally driver training and testing facilities for teams and individuals, and competitive events. Some of the existing tracks will be used for the construction and maintenance of the turbines and will be widened as necessary to achieve a minimum width of 5m. Some of the existing tracks are already wide enough and will be surfaced as required. The total length of existing tracks to be used for the development is 9.5km.

13.9 In summary the proposed wind farm development would consist of the following:

• 27 turbines up to 125m to tip;

• electrical cables;



• substation, control building and satellite link;

• widening of existing tracks (approximately 9.5km to be widened);

• approximately 6.9km of new tracks; and

• installation of a meteorological mast.

13.10 An indicative site layout is shown in Figure 2.1.

Proposed Turbine Details

13.11 WYG has been advised by Mynydd y Gwynt Ltd that no specific make or model of turbine is being applied for; visualisation and noise calculations undertaken to date have been based on a Vestas V90 3MW turbine, hence that is considered in this assessment. The exact turbine model and specification would be agreed with the consenting authorities prior to construction as addressed in Chapter 2. As set out in that chapter with the ongoing advances in turbine design, by the time of construction other model options may be available. The Vestas V90 turbine’s broad specifications are outlined in Table 13.1.

Table 13.1: Proposed Turbine

Proposed Manufacturer Vestas

Proposed Model V90

Power Output 3MW

Maximum Height to Tip 125m

Blade 44m

Tower Type Tubular Steel

POLICY CONTEXT

Introduction

13.12 A review of relevant transport and planning policies has been undertaken and is summarised below. The review provides the basis for the wider development context of the wind farm proposals.

National Policy Statements

13.13 The Department of Energy and Climate Change (“DECC”) in its Overarching National Policy Statement for Energy (EN-1), July 2011 sets out the national policy for energy infrastructure, including on-shore wind generation. EN-1 reviews the traffic and transport elements of strategic projects and states that:

“Provided that the applicant is willing to enter into planning obligations or requirements can be imposed to mitigate transport impacts identified in the NATA/WebTAG transport assessment, with attribution of costs calculated in accordance with the Department for Transport’s guidance, then development consent should not be withheld, and appropriately limited weight should be applied to residual effects on the surrounding transport infrastructure”.



Planning Policy Wales (Welsh Government (“WG”) 2014)

13.14 Planning Policy Wales 6 (“PPW”) Chapter 8: Transport states that the following should be taken into account when determining a planning application for development that has transport implications:

• “the willingness of a developer %to provide infrastructure or measures to manage traffic, to overcome transport objections to the proposed development%;

• the environmental impact of both transport infrastructure and the traffic generated; and

• the effects on the safety and convenience of other users of the transport network”.

Planning Policy Wales Technical Advice Note 18: Transport (“TAN18”)

13.15 TAN 18 was published in March 2007 and reinforces the principle aims of PPW. It describes how to integrate land use and transport planning and explains how transport impacts should be assessed and mitigated.

13.16 Key requirements of TAN 18 that are applicable to this development include:

• ensuring that transport infrastructure or service improvements necessary to serve new development allow existing transport networks to continue to perform their identified functions (para 2.3, page 3);

• submission of Transport Assessments to accompany planning applications for developments that are likely to result in significant trip generation (para 9.2, page 36);

• access to be provided that reflects the nature and type of road and the volume and character of traffic likely to use the access and the road (para 9.16, para 39);

• any works to the Trunk Road resulting from the development to be constructed to the standards applied to its own schemes (para 9.17, page 39); and

• where transport improvements are required in the vicinity of the scheme and beyond to accommodate trips associated with the development, conditions may be imposed to make its commencement/ occupation subject to the completion of those works or a developer may be invited to conclude an agreement under section 278 of the highways Act 1980 for the provision of highway works (para 9.18, page 40).

National Transport Plan

13.17 The National Transport Plan (“NTP”) was first published by the Welsh Assembly Government (“WAG”) in July 2009 and was updated in March 2010. It sits alongside the Regional Transport Plans in delivering the Wales Transport Strategy and sets out a series of proposed transport interventions across Wales, as well as targeted proposals along specified main movement corridors.



Regional Transport Plan

13.18 Trafnidiaeth Canolbarth Cymru (“TraCC”) is the Regional Transport Partnership for Mid Wales. It is a voluntary partnership between the three Mid Wales unitary authorities – Ceredigion, Gwynedd and Powys. TraCC published its Regional Transport Plan (“RTP”) in September 2009.

13.19 The RTP refers to the number of turbines likely to be constructed in Mid Wales to achieve WAG’s renewable energy targets. It outlines the anticipated increase in heavy goods vehicle movements, associated disruption to the travelling public and roadside communities, and resulting impact on highway surfaces and structures. The RTP does not set out a strategy for mitigating these effects but does state that TraCC will work with WAG and other affected parties to develop a strategic approach.

Powys Unitary Development Plan

13.20 The Powys Unitary Development Plan (“UDP”) was adopted in March 2010. It provides the policy framework for guiding development across Powys through to 2016.

13.21 Policy E3 of the UDP specifically relates to wind power development and states that applications for wind farms will be approved where they do not “unacceptably adversely affect the enjoyment and safe use of highways and the public rights of way network, especially bridleways (including during the construction phase)”. It also states that wind farm approvals will be granted where “they are capable of being served by an acceptable means of highway access and any new or improved roads and accesses required would not have unacceptable environmental impacts”.

13.22 Powys County Council is currently in the process of preparing a Local Development Plan (LDP) that will ultimately replace the UDP.

Ceredigion Unitary Development Plan

13.23 The Ceredigion UDP sets out the land use policy framework for the development and use of land and buildings in the County over the 15-year period 2001 to 2016. Work on the UDP has ceased to allow the LDP process to be taken forward but the 2002 deposit document is being used in determining planning applications.

13.24 The UDP does not contain any specific policies in relation to wind farm access or highways impact but the general transport policy T1.1 Location of Development notes that “development of an appropriate scale and character will be permitted where the developer can demonstrate that there are unlikely to be any unacceptable adverse impacts from its location, taking into account the accessibility of the site by a range of transport modes; the trip generation of the proposed use; the impact on access and highway arrangements”.

Draft General Principles for the use of Trunk Roads in Wales for the Movement of Abnormal Indivisible Loads

13.25 A number of Highway Authorities have collaborated to produce guiding principles for the management of abnormal load deliveries across north and mid Wales.

13.26 The draft document produced in 2011 identifies preferred routes for accessing Strategic Search Areas and that for Search Area D is consistent with the route proposed for the Mynydd y Gwynt wind farm.



13.27 Many of the principles outlined in this document are likely to be reflected in the Strategic Traffic Management Plan for Mid Wales undertaken by Renewable UK Cymru and that has been partially approved at the time of writing.

Study methodology

Introduction

13.28 There are three stages that this assessment needs to consider:

• The Construction Phase of the project;

• The Operational Phase of the project; and

• The Decommissioning Phase of the project (typically undertaken 25 years following commissioning).

Project Phases – Transport Overview

13.29 Of these phases, the greatest traffic volumes are associated with the project construction phase. The operational phases are restricted to occasional maintenance operations which generate much lower volumes of traffic that are not considered to be in excess of daily traffic variation levels on the road network.

13.30 The decommissioning phase involves fewer trips on the network than the construction phase as elements of infrastructure such as access tracks are often left in place, adding to local infrastructure.

13.31 The worst case transport scenario is therefore the construction phase and this assessment concentrates on that element of the project’s life. It should be borne in mind however that the construction impacts are temporary in nature and very short lived.

Assessment Scope

13.32 The assessment has been carried out using the Transport Assessment guidance contained within TAN 18. Until mid-2013 SSE Renewables was proposing the Nant y Moch wind farm, in SSA D to the West of this scheme. The Nant y Moch scheme proposed turbines with very similar physical characteristics, albeit a larger number (50+) of them. As a result WYG has used a similar study area and scope as that used by SSE Renewables for the assessment of the Nant y Moch scheme.

13.33 A review of the traffic impact and the feasibility of transporting turbines to the development site has been undertaken.

Baseline conditions

Data Collection Methodology

13.34 WYG obtained Automatic Traffic Count (“ATC”) from Traffic Wales to allow an accurate estimate to be made of the potential impact of the construction phase of the proposed wind farm development.

13.35 Six relevant survey sites were identified as follows:



• A44 Llanbadarn East;

• A44 east of A4159 Lovesgrove;

• A44 west of Llangurig;

• A470 Cwmbelan Powys, south of Llanidloes;

• A470 Llanidloes BP Powys; and

• A470 south of Llangurig Powys.

13.36 The locations of the traffic count sites are illustrated in Figure 13.1.

13.37 Count data was requested for the most recent week available across the sites on each road for normal traffic flow conditions. For the A470 sites, all data relates to week commencing Monday 20th February 2012. For the A44 sites, the most recent week for which data was available for all sites dated from 2005 which was considered too old to be sufficiently robust. Data was therefore selected for a recent neutral week according to the counts available for each site as follows:

• A44 Llanbadarn East – Monday 31st January 2011;

• A44 east of A4159 Lovesgrove – Monday 24th October 2011; and

• A44 west of Llangurig - Monday 19th October 2009.

Baseline Traffic Conditions

13.38 The data provided split traffic flows into volume by direction and at some of the sites included speed data.

13.39 Tables 13.2 and 13.3 summarise the traffic data at the seven sites during the weekday and weekend scenarios.

Table 13.2: Existing Traffic Conditions (Weekday Average Two-Way Flows)

Survey Location Time Period Flow

A44 Llanbadarn East 12 Hour Flow 9324

24 hour Flow 11155

A44 East of A4159 Lovesgrove 12 Hour Flow 4762

24 hour Flow 5457

A44 west of Llangurig 12 Hour Flow 3763

24 hour Flow 4325

A470 Cwmbelan Powys, south of Llanidloes 12 Hour Flow 3565

24 hour Flow 4355

A470 Llanidloes BP Powys 12 Hour Flow 3363

24 hour Flow 4003

A470 south of Llangurig Powys 12 Hour Flow 2628

24 hour Flow 3065



Table 13.3: Existing Traffic Conditions (Weekend Average Two-Way Flows)



24 hour Flow 9584

A44 east of A4159 Lovesgrove 12 Hour Flow 5290

24 hour Flow 6222


24 hour Flow 6221


24 hour Flow 3475


24 hour Flow 3152


24 hour Flow 2397

Future Traffic Conditions

13.40 Construction of the project is due to commence in 2018 if consent is granted. For the purpose of this assessment, a 13 month construction period is assumed. The exact start time in 2018 is not yet known and as such an assessment year of 2019 has been assumed as a worst case scenario.

13.41 Any lengthening in the programme however will have a reduced impact on the surrounding road network in overall trip generation terms.

13.42 To assess the likely impacts during the construction phase, base year traffic flows were assessed by applying the National Road Traffic Forecast (“NRTF”) high growth factors to the surveyed traffic flows. Applying high growth factors provides a robust assessment as they represent higher than average growth.

13.43 The NRTF high growths factors applied to the survey data to estimate 2019 traffic flows are:

• 2009 to 2019 – 1.184;

• 2010 to 2019 – 1.163;

• 2011 to 2019 – 1.142; and

• 2012 to 2019 – 1.122.

13.44 The final 2019 traffic flows are shown in Tables 13.4 and 13.5.



Table 13.4: Future Year Traffic Conditions (Weekday Average Two-Way Flows)



24 hour Flow 12739


24 hour Flow 6232


24 hour Flow 5121


24 hour Flow 4886


24 hour Flow 4491


24 hour Flow 3439

Table 13.5: Future Year Traffic Conditions (Weekend Average Two-Way Flows)



24 hour Flow 10945


24 hour Flow 7106


24 hour Flow 7366


24 hour Flow 3899


24 hour Flow 3537


24 hour Flow 2689

Speed Survey

13.45 Five of the ATC sites used to provide traffic volume data were also used to collect speed statistics. The 5-day average and 85th percentile speeds observed at the count locations are summarised below in Table 13.6.

Table 13.6: Speed Summary

Average Speed

(MPH)

85th Percentile

Speed (MPH) Speed Limit

(MPH)

A44 east of A4159 Lovesgrove 45.0 52.4 30

A44 west of Llangurig 60.3 69.25 30

A470 Cwmbelan Powys, south of 56.6 65.3 60



Llanidloes

A470 Llanidloes BP Powys 56.9 66.5 60

A470 south of Llangurig Powys 52.5 61.4 60

Accident History

13.46 WYG obtained road traffic accident data for the five years from the start of 2006 over the following links:

• A44 between junction with A4971 Aberystwyth and junction with A470 at Llangurig - a 39km stretch;

• A470 between junction with A470 at Llangurig and Llanidloes – a 9km stretch; and

• A470 between junction with A470 at Llangurig and Rhayader – a 15km stretch.

13.47 The accident data indicates that over the full study area which totals 63km, an average of 34 accidents occurs every year of which around 74% are classified as “slight”.

13.48 On the 20km section of the A44 between its junctions with the A4159 and A470, there were on average 5 accidents every year of which around 59% are classified as “slight”.

Footpath Network

13.49 There are a number of footpaths and bridleways that pass through the site, one of which will be affected during the construction period. One footpath lying to the north of the site will be adjacent to one of the site tracks, following the course of an existing track. The new track will be constructed parallel to the footpath, which will be fence protected for the duration of the construction works. Further information is given in Chapter 6, Paragraphs 6.14 to 6.16.

Development Trips

Derivation of Development Traffic

13.50 During the 13 month construction period, the following traffic will require access to the site:

• staff transport, either cars or staff minibuses;

• construction equipment and materials, deliveries of machinery and supplies such as cement; and

• abnormal loads consisting of the wind turbine sections and also a heavy lift crane.

13.51 Average monthly traffic flow data was used to establish the construction trips associated with the site based on the assumptions detailed in the following sections.

Staff Traffic

13.52 Staff will arrive in non-HGV vehicles and where possible will be encouraged to car share. The workforce on-site will depend on the activities undertaken, but, based on previous wind farm construction site experience, the average number is expected to be around 42 for the



full duration of the project. The peak staff numbers occurs for a short time period and is likely to be based on three staff per turbine resulting in a maximum number of 81 staff.

13.53 For the purposes of estimating traffic movements, it has been assumed that 66% of staff would be transported by minibus carrying up to 16 people and 33% would arrive by car (single car occupancy has been assumed as the worst case at this stage with potentially fewer movements through car sharing).

13.54 Based on these assumptions, staff transport cars and light vehicles would account for 64 vehicle trips (32 trips inbound and 32 trips outbound) per day during the peak of construction.

Construction Traffic

13.55 An estimate of concrete and steel reinforcement requirements for the turbine foundations was based on a worst case scenario in which the concrete is batched off-site and arrives in mixers for immediate pouring. The total estimated trips required for the delivery of the concrete and reinforcement is summarised in Table 13.7 and Table 13.8 respectively.

Table 13.7: Ready Mix Deliveries

Foundation Volume (m³)

No.

Turbines

Total

Volume (m³)

Lorry

Capacity (m³)

No.

Lorries

No. of

Movements

411 27 11,097 6 1850 3700

Table 13.8: Steel Reinforcement Deliveries

Foundation Volume (t)

No.

Turbines

Total

Weight (t)

Lorry

Capacity (t)

No.

Lorries

No. of

Movements

50 27 1,350 30 45 90

13.56 Electrical cables will be laid in trenches. The total estimated number of trips required to deliver the cabling is summarised in Table 13.9.

Table 13.9: Cabling Movements

Length of Cable Run (m)

Length Per Drum (M)

No. of Drums

Drums Per Lorry

No.

Lorries

No. of

Movements

16,060 500 96 9 11 21

13.57 The cables will be buried in sand to protect them from damage. Cabling sand would be imported to the site. The total estimated number of trips required to deliver the cabling sand is summarised in Table 13.10.



Table 13.10: Cabling Trench Movements

Length of Cable Run (m)

Trench Cross-Section (m²)

Total Volume (m³)

Density (te/m³)

No.

Lorries

No. of

Movements

16,060 0.338 5,420 2 434 867

13.58 Materials will be required to construct the wearing course of the access tracks, new access track sections and crane pads. The total estimated volume of material required to provide road foundations is 41,000m3. It is understood that all of the track construction material will be imported. This is illustrated in Table 13.11.

Table 13.11: Track Construction Movements

Volume Required (m³)

Density (te/m³)

Total (te)

Tipper Capacity (te)

No.

Tippers

No. of

Movements

41,000 2 82,000 20 4,100 8,200

13.59 The imported material will be brought in two phases, where new track material will be imported in a pre-construction phase of three months in line with NRW guidance to let new tracks to settle. This pre-construction phase is illustrated in Table 13.12.

Table 13.12: Pre Construction General Trip Distribution

Activity

Month

1 2 3

Site mobilisation 60 60

General site delivery vehicles

24 24 24

Earth moving plant 20 20

Imported stone 1100 1100 1100

Geotextile separators 43 43

Staff 440 440 440

Service (food/water etc.) 44 44 44

Total estimated movements 1671 1651 1628

Working Days 22 22 22

Daily Average 76 75 74

13.60 It is assumed that there will be one service delivery (food/drink) per working day throughout the 13 month programme. This equates to 44 vehicle movements per month (22 trips inbound and 22 trips outbound). A 22 day working month has been assumed.



13.61 In addition, further items will be required to be transported to the site during the construction phase. These items are detailed in the main delivery schedule table provided in later sections and include the materials for the small control building.

Turbine Transport

13.62 The turbines are broken down into components for transport to the site. The nacelle, blade and tower sections are classified as Abnormal Indivisible Loads (“AIL”) due to their weight, length, width and height when loaded. For the purposes of the report, the numbers of components requiring transport are illustrated in Table 13.13 for the proposed V90 machine. It should be noted that the actual turbines installed on the site may have fewer tower sections, resulting in fewer loads being transported to the site.

Table 13.13: Turbine Components

Component No. per Turbine

Rotor Blades 3

Tower Top 1

Mid Tower 1

Tower Base 1

Nacelle 1

Hub 1

Container 1

Nose Cone 1

Footings 1

Site parts (shared Containers) 0.2

Total Movements 11.2

Number of Turbines 27

Total Vehicle Trips 302

Total Vehicle Movements 604

Total Construction Traffic

13.63 The total estimated construction traffic movements are detailed in the main delivery schedule table provided in Table 13.14.

13.64 The results conclude that Month 8 is likely to be the peak period for the construction period with an average of 143 movements per day (72 trips in and 72 trips out).

13.65 The subsequent traffic impact assessments will therefore focus on the peak period traffic flows to illustrate the potential impacts on the study network.



Table 13.14: General Trip Distribution

Activity

Month

1 2 3 4 5 6 7 8 9 10 11 12 13

Total

Movements

Vehicle

Class

Site mobilisation

120 120 120 120 600 OGV2

General site delivery vehicles

4 12 20 24 30 32 36 40 40 40 40 20 4 414 OGV2

Earth moving plant

10 20 20 30 120 OGV2

Imported stone

980 980 980 980 980 8200 OGV2

Reinforcement

30 30 30 90 OGV2

Off-Site Batched Concrete

1233 1233 1233 3699 OGV2

Control Building

24 24 48 OGV3

Cable Deliveries

11 11 22 OGV2

Cabling Sand 434 434 868 OGV2

Geotextile separators

86 OGV2

Delivery of HV electrical items

16 16 32 OGV2

Cranage and related vehicles

30 30 60 OGV2

AIL Escorts 216 216 216 216 864 Car+LGV

Turbine transporters

151 151 151 151 604 OGV2

Staff 141 423 704 845 1056 1127 1268 1408 1408 1408 1408 704 141 13361 Car+LGV

Service (food/water etc.)

44 44 44 44 44 44 44 44 44 44 44 44 44 704 OGV1

Total estimated movements

1299 1599 1748 1893 2591 2911 2627 3152 1883 1883 1859 948 309 29652

Working Days

22 22 22 22 22 22 22 22 22 22 22 22 22

Daily Average

59 73 79 86 118 132 119 143 86 86 85 43 14



Trip Distribution

13.66 The distribution of development trips on the network will vary depending on the types of loads being transported.

13.67 All construction traffic will enter the site by way of the proposed access junction on the A44.

13.68 Staff trips were assumed to be distributed in line with the proportional volumes of traffic flow on the main routes as collected during the traffic surveys. The proposed distribution of these trips is provided in Table 13.15.

Table 13.15: General Trip Distribution

Origin Point Percentage Distribution

A44 west 38%

A470 north/ A44 east 36%

A470 south/ A44 east 26%

A44 Site Access 100%

13.69 More specialist deliveries have different distributions on the network. The distributions for these trips were based on the following assumptions:

• all abnormal turbine loads will originate from Swansea and ultimately access the site via Aberystwyth and A44;

• all crane trips will access and egress by way of the A44 west;

• all imported stone is sourced from local quarries. There are a number of quarries located throughout the area and it is therefore assumed that vehicles would route equally via A44/ A470 north/ A470 south;

• all concrete deliveries are sourced from local ready mix sites. It is assumed that vehicles would route equally via A44/ A470 north/ A470 south; and

• all other deliveries assumed to route equally via A44/ A470 north/ A470 south.

Impact Identification

13.70 The future year traffic survey data was combined with the estimated peak daily construction traffic flows to estimate the total trips on the study network during the construction phase.

13.71 Table 13.16 details 2019 average weekday traffic flows, estimated levels of daily construction traffic and the percentage increase in traffic for the 12 and 24 hour periods.



Table 13.16: Combined 2019 Weekday Base Traffic Flows / Construction Phase Trips / Weekday Percentage Impact

Survey Location

Time Period 2019 Base Flow


(Impact %)

A44 Llanbadarn East 12 Hour Flow 10648 46 0.43%

24 hour Flow 12739 46 0.36%

A44 east of A4159 Lovesgrove

12 Hour Flow 5438 46 0.85%

24 hour Flow 6232 46 0.74%

A44 west of Llangurig 12 Hour Flow 4455 85 1.91%

24 hour Flow 5121 85 1.66%

A470 Cwmbelan Powys, south of Llanidloes

12 Hour Flow 4000 45 1.13%

24 hour Flow 4886 45 0.92%

A470 Llanidloes BP Powys 12 Hour Flow 3773 45 1.19%

24 hour Flow 4491 45 1.00%

A470 south of Llangurig Powys

12 Hour Flow 2949 40 1.36%

24 hour Flow 3439 40 1.16%

Sensitivity Tests

Weekend Traffic Flows

13.72 Whilst no significant weekend working is anticipated, a sensitivity review for weekend flow using the weekday construction traffic was undertaken for illustrative purposes. This is shown in Table 13.17.

Table 13.17: Combined 2019 Weekend Base Traffic Flows / Construction Phase Trips / Weekend Percentage Impact

Survey Location



(Impact %)

A44 Llanbadarn East 12 Hour Flow 9017 46 0.51%

24 hour Flow 10945 46 0.42%


12 Hour Flow 6041 46 0.76%

24 hour Flow 7106 46 0.65%

A44 west of Llangurig 12 Hour Flow 6440 85 1.32%

24 hour Flow 7366 85 1.15%


12 Hour Flow 3116 45 1.44%

24 hour Flow 3899 45 1.15%

A470 Llanidloes BP Powys 12 Hour Flow 2980 45 1.51%

24 hour Flow 3537 45 1.27%


12 Hour Flow 2324 40 1.72%

24 hour Flow 2689 40 1.49%



13.73 It is highly likely that weekend activities will be restricted through planning conditions to only allow general site maintenance, rather than full construction.

13.74 As no significant weekend working is anticipated, the above sensitivity review looking at the impact of weekday construction traffic on weekend traffic flows is provided for illustrative purposes only. No more detailed analysis has been undertaken.

Sensitivity Assessment Impact – Nant y Moch

13.75 A sensitivity test was undertaken which considers the cumulative impact of the proposed Mynydd y Gwynt wind farm and the proposed Nant y Moch wind farm to the east.

13.76 The future year traffic survey data was combined with the Mynydd y Gwynt and Nant y Moch peak daily traffic flows (the latter taken from the Nant y Moch Wind Farm EIA) to estimate the total trips on the study network during the construction phase. This assumes that the two wind farms are constructed simultaneously with the peak periods of construction also occurring simultaneously. Table 13.18 illustrates the increase in average traffic flows along with the percentage increase in total traffic for the 24 hour periods. The Nant y Moch assessment does not consider traffic routeing via A470. It was therefore assumed that traffic approaching the site via A44 west of Llangurig would route equally via A470 north and south.

Table 13.18: 2019 Weekday Base Traffic Flows / Combined Construction Phase Trips / Combined Percentage Impact

Survey Location


Combined Construction Traffic

(Impact %)

A44 Llanbadarn East 24 hour Flow 12739 46 + 171 1.70%


24 hour Flow 6232 46 + 171 3.48%

A44 west of Llangurig 24 hour Flow 5121 85 + 171 5.00%


24 hour Flow 4886 45 + 86 2.68%

A470 Llanidloes BP Powys 24 hour Flow 4491 45 + 86 2.92%


24 hour Flow 3439 40 + 82 3.55%

13.77 This assessment has been undertaken notwithstanding the fact that the Nant y Moch wind farm is not presently proceeding, with its promoter, SSE Renewables having cancelled its grid connection contract. The assessment nonetheless provides an illustration of the possible “worst case”. Even had Nant y Moch been proceeding, it would be very unlikely that the two wind farms would be constructed in the same period, less likely that the peak periods of construction would overlap. As the maximum impact predicted on all these worst case predictions aligning is 5.0% per day, no detailed review of the combined assessment results has been undertaken.



Decommissioning Traffic Estimates

13.78 It is anticipated the number of associated movements will be less than during the construction phase and that the number of abnormal loads will be drastically reduced as described in the dedicated Decommissioning Chapter of the submission.

13.79 An assessment of the likely traffic volumes has been undertaken using the proposed decommissioning methodology and material estimates. It is estimated that up to a quarter of the concrete from the turbine bases and substation would be recovered and that up to 40% (worst case) of new top soil would be required to be imported to cover over the foundations to the suggested depths.

13.80 Given that sections such as the turbine blades could be broken down on site, the numbers of abnormal loads and their attendant escorts is reduced. The number of staff required to decommission the site is also significantly less than that required to construct it and this is also reflected in the traffic estimates. The potential number of decommissioning trips is provided in Table 13.19.

Table 13.19: Decommissioning Phase Traffic Volumes

Activity

Month

1 2 3 4 5 6 Total

Movements

Vehicle Class

Site mobilisation 20 20 40 OGV2

Earth moving plant 10 10 20 OGV2

Imported soil 303 303 303 303 304 304 1820 OGV2

Concrete Removal 68 68 68 68 270 OGV2

Cable Removals 8 8 16 OGV2

Removal of HV electrical items 8 8 16 OGV2

Cranage and related vehicles 15 15 30 OGV2

AIL Escorts 136 136 136 136 544 Car+LGV

Turbine transporters 135 135 135 135 540 OGV2

Staff 674 748 748 748 748 599 4265 Car+LGV

Service (food/water etc.) 10 10 10 10 10 10 60 OGV1

Total estimated movements 1311 1408 1400 1400 1153 951 7621

Working Days 22 22 22 22 22 22

Daily Average 60 64 64 64 52 43



13.81 The subsequent impact of the loads on the surrounding network will substantially reduced as will the potential for minor disruption associated with the lower number of abnormal loads.

13.82 The overall traffic generation associated with the decommissioning phase is less than 40% of the proposed construction phase. As such the percentage impacts on the associated study links will be substantially reduced as will the resultant effects on the transport impacted environment.

Impact Review

Construction Phase – IEMA Assessment

13.83 In accordance with the Institute of Environmental Management Assessment (“IEMA”) Guidelines for the Environmental Assessment of Road Traffic, an assessment should be undertaken:

• On road links where traffic flows are predicted to increase by more than 30% (or where the number of heavy goods vehicles is predicted to increase by more than 30%); and

• Traffic flows are predicted by 10% or more in any other specifically sensitive areas.

13.84 HGV traffic levels are projected to increase on all roads within the study network in the weekday, although the actual number per day is considered low at 80 movements (40 inbound and 40 outbound per day on average, equating to approximately 5 inbound trips per hour).

13.85 Under the IEMA guidelines, none of the links would be considered critical even when the cumulative impact of this wind farm development together with the formerly proposed Nant y Moch wind farm, the worst case. However, a route evaluation has been carried out for the A44 against a number of environmental criteria. It should be noted that this represents a high level overview and a more detailed environmental assessment at certain points along the route may be required (e.g. if trees are to be felled).

13.86 Table 13.20 summarises the potential impact of the increase in traffic on different environmental receptors identified in the IEMA Guidance.

Table 13.20: A44 Link Review

Receptor Potential Effect

Magnitude of Effect

Comment

Humans

Traffic Noise Low/Medium Increase in traffic could result in additional noise impacts, although this would only be temporary during the construction period and on properties abutting the road.

Vibration Low/Medium Increase in traffic could result in additional vibration impacts, although this would only be temporary in nature and localised to properties immediately abutting the road.



Visual Impact Low/Medium The increase in movements by high-sided vehicles could result in visual intrusion, although this would be limited to the construction period only.

Severance Low There are no footways within 5km of the site on the A44. Access to an existing footpath will be affected by construction but an alternative route will be provided. On this basis severance is unlikely to be an issue.

Driver Delay Low/Medium Driver delay would largely occur during the movement of the abnormal loads.

Pedestrian Delay

Low There are no footways within 5km of the site and access to Core Paths will be affected by construction. On this basis pedestrian delay is unlikely to be an issue.

Pedestrian Amenity

Low There are no footways within 5km of the site. On this basis pedestrian amenity is unlikely to be an issue.

Accidents and Safety

Low There is limited potential for impact on safety due to driver frustration, particularly with regards to the transport of the abnormal loads.

Hazardous Loads

Low It is highly unlikely that any abnormally hazardous materials would be transported to / from site.

Air Pollution Low An increase in traffic is often associated with an increase in air pollution; however it is unlikely the volume of movements and temporary nature would pose a significant impact.

Dust and Dirt Low/Medium There is the potential for dust and dirt to be distributed on the public road by vehicles exiting the site. A wheel wash facility will be provided to reduce the impact of any such occurrences

Ecology

Low/Medium Some side vegetation will need to be removed from the roads. To avoid any impact upon nesting birds this should be removed outside of the breeding season (March to August).

Material Assets Heritage and Conservation Areas

Low No significant impacts are considered likely.



Operational Traffic

13.87 It is predicted that during the operation of the site there will be up to 2 vehicle movements per week for maintenance purposes. Also, there may be occasional abnormal load movements to deliver replacement components in the event of a major failure.

Decommissioning Traffic

13.88 Prior to decommissioning of the site, anticipated to be 25 years from the opening year, a revised traffic assessment will be undertaken and appropriate traffic management procedures followed. It is anticipated the number of associated movements during decommissioning will be approximately 26% of those predicted during the construction phase and that the number of abnormal loads will be reduced.

General Construction Traffic Mitigation

13.89 During the construction period the developer (through their consultant) and contractor will maintain a website containing the latest information relating to traffic movements associated with vehicles accessing the development site. This will be agreed with the local roads authority.

13.90 The following measures are recommended in terms of site operation and maintenance during the construction phase;

• All materials delivery lorries (dry materials) should be sheeted to reduce dust and stop spillage on public roads; and

• Specific training and disciplinary measures should be established to ensure the highest standards are maintained to prevent construction vehicles from carrying mud and debris onto the carriageway, wheel wash facilities will be established at the site entrance.

13.91 A Construction Method Statement (“CMS”) will set out measures to be put in place to reduce the impact of noise, dust and excessive speed.

13.92 Table 13.21 indicates the proposed mitigation measures that the developer intends to use to mitigate or reduce the impact of the potential effects of the development.

Table 13.21: Mitigation Proposals

Potential Effect Proposed Mitigation

Traffic Noise and Vibration

As there are very limited numbers of properties abutting the A44 on the sections east and west of the proposed modified site access junction, traffic noise and vibration are unlikely to be an issue. As noise and vibration are speed dependant, vehicles will be fitted with identification numbers to allow the public to identify any vehicles that may be speeding or causing specific issues and drivers will be required to pass through sensitive areas at low speed.

Visual Impact

All mitigation works to accommodate abnormal load traffic will be designed to be temporary in nature and will be restored to their original condition (unless requested otherwise by the Roads Authorities)



Severance There are no footways or settlements within 5km of the site. On this basis severance is unlikely to be an issue.

Driver Delay

General construction traffic is unlikely to create significant levels of driver delay. The detailed Traffic Management Plan will set out measures to help reduce delays encountered with abnormal load transport. This will include measures such as timing deliveries during off-peak periods.

Whilst significant delays should not be encountered with abnormal load transport, as set out in the Traffic Management Plan, other measures such as advance warning signs will help drivers consider non-impacted routes as alternatives for their journeys.

Pedestrian Delay

There are no footways within 5km of the site on the A44. The Traffic Management Plan associated with the transport of abnormal loads will address any pedestrian delay issues that could occur during convoy movements. Access for pedestrians within the site will be mitigated through the provision of an alternative route that would have negligible impact on journey times for walkers.

Pedestrian Amenity

There are no footways within 5km of the site on the A44, some low levels of informal pedestrian use of the verge may be encountered. The Traffic Management Plan associated with the transport of abnormal loads will address any pedestrian amenity issues that could occur during convoy movements.

Accidents and Safety

The abnormal loads will be escorted by the Police and operated in accordance with a Traffic Management Plan that reviews all risks for all road users. Advance warning signs will be used to provide advice and warnings to road users and a wheel wash facility will be provided to ensure that no mud and debris is brought onto the public highway.

Air Pollution Wherever possible, contractors will be encouraged to use low emissions vehicles through the Construction Management Plan.

Dust and Dirt

A wheel wash facility is to be provided on site and contractors will be required to sheet over all loose material deliveries. A road sweeper will also be deployed on the section of the A44 adjacent to the site access to ensure that the road is kept clean and free running.

Ecology The trimming back of tree canopy cover and side vegetation is unlikely to have a significant long lasting adverse impact.

Operational Phase Mitigation

13.93 Site entrance roads will be well maintained and monitored and road cleaners will be available to remove material carried onto public roads by any maintenance traffic travelling to the site when operational.

Decommissioning Phase Mitigation

13.94 Similar to the construction phase, a Traffic Management Plan will be prepared for the decommissioning phase. Similar mitigation proposals will be deployed as appropriate.



Residual Impact Assessment

13.95 With mitigation measures in place no significant residual impacts are anticipated.

Abnormal load Access Review

Component & Transport Details

13.96 The turbines are broken down into components for transport to the site. The nacelle ring, blade and base / intermediate and top tower sections are classified as AIL due to their weight, length, width and height when loaded.

13.97 The main AIL elements of the predicted loads of this project are summarised in Table 13.22.

Table 13.22: Typical Turbine Components

Component Number per turbine

Blade 3

Hub 1

Nacelle 1

Base Tower Section 1

Intermediate Tower Section 1

Top Tower Section 1

13.98 The components can be delivered on a variety of transport platforms, with typical examples illustrated in Photos 13.1 and 13.2.

Photo 13.1: Typical blade transport



Photo 13.2: Typical tower transport

13.99 The blades and tower sections are considered as abnormal loads due to their size, whilst the hub and nacelle ring join this category due to their weight. Other components such as the nosecone, footings and tool boxes are transported using standard HGV vehicles. A typical turbine of this scale can be delivered in up to 11 deliveries (of which 8 are considered abnormal).

13.100 The total number of abnormal loads associated with the construction of the Mynydd y Gwynt development is 216. This may vary slightly depending upon the final choice of turbine.

13.101 The Welsh Police have advised that they will escort up to two abnormal loads as a single convoy (although if the delivery process is successful, it may be possible to increase the number of components per convoy to three). Assuming the worst case scenario of two component parts, it is predicted that up to 108 individual convoys would deliver to the site.

13.102 In addition to the turbine deliveries, a large erection crane would be needed to offload a number of components and erect the turbine. The crane is likely to be a mobile crane with a capacity up to 800 tonnes that is escorted by boom and ballast trucks to allow full mobilisation of the crane on site. A smaller erector crane will also be present to allow the assembly of the main crane and to ease overall erection of the turbines.

13.103 The decommissioning of the turbines would result in a similar number of abnormal loads as during the construction phase, with the blades, nacelle, hub and towers being removed. However, it is possible that the turbines could be cut up on site meaning they could be transported off site using standard vehicles. Environmental investigations would be undertaken at an appropriate time to determine whether in situ breakdown would be acceptable.

13.104 At this point in time, it is predicted that the foundations will remain in situ.



Port of Entry (“POE”)

13.105 Following desktop reviews of all potential access routes from the PoE to the Mynydd y Gwynt Wind Farm and a review of a ‘Route Access Survey’ undertaken by Collett Transport for Mynydd y Gwynt Ltd, Swansea has been chosen as the Port of Entry for all loads associated with the Mynydd y Gwynt Wind Farm. During the development life of the project the Aberleri Boatyard at Borth was considered as a possible Port of Entry to reduce distances travelled on the highway network for AILs. However modifications required in the harbour would have had greater potential ecological impacts on the SSSI so this option was abandoned some years ago.

13.106 It should be noted that much of this work was carried out jointly with SSE Renewables, as their formerly proposed scheme at Nant y Moch was proposed on the basis that it would adopt the same abnormal load delivery route as is proposed for the Mynydd y Gwynt scheme, from Swansea Port to their site entrance on the A44 west of Ponterwyd.

Route from POE to Site

13.107 It is proposed that all loads will depart Swansea Port and approach the sites from the south via Cardigan and Aberystwyth. Figure 13.2 illustrates the main route that the abnormal loads will take.

13.108 The proposed tower and blade access routes would take the loads along Fabian Way (A483) out of Swansea Port where the loads will merge onto the M4 at Junction 42 heading east. The proposed route from Swansea to the M4 has been used previously for the transport of wind turbine components to site, the exit from the port having been improved and largely constructed for the purpose of serving the Blaengwen wind farm.

13.109 At Pontabraham Roundabout the loads will leave the M4 and continue onto the A48 (Junction 49). To the south of Carmarthen, the AILs will continue onto the A40 westbound. At Penblewin Roundabout all loads will turn right onto the A478, travelling northbound. Approaching from the south of Cardigan, the loads will turn right onto the A487 eastbound. At Penparcau Road Roundabout to the south of Aberystwyth AILs will turn right onto the A4120, continuing north and turn right at the Heol-y-Bont roundabout. At the junction with the A44, the loads will turn right and continue east to the proposed site at Mynydd y Gwynt.

13.110 The total route from Swansea Port to Mynydd y Gwynt is approximately 130 miles.

13.111 The clear advantage of the proposed route between Swansea and the site is that it spreads the impact away from the Welsh Government’s strategic routes from the east and north.

Constraint Assessment

13.112 Mynydd y Gwynt Limited and SSE Renewables previously commissioned Collett Transport to undertake a Route Access Study of the access route from Swansea Port on the A483 through to the site accesses for the Mynydd y Gwynt and the formally proposed Nant-y-Moch wind farms. This review highlighted a number of constraint points which were assessed by Collett Transport using swept path assessment software.

13.113 In May 2012 WYG arranged an AIL test run to review in more detail the need for road works associated with the two wind farms. The test run was arranged through Give



Svaergods Transport Limited and the vehicles were escorted by members of South Wales/ Dyfed Powys Constabularies. The test run was recorded and then used to validate the swept path assessments undertaken by Collett Transport and subsequently reviewed by WYG.

13.114 A test run report which identifies the key points and issues associated with the route that require remedial works to accommodate the predicted loads was produced. The results and recommendations contained in the report are summarised below:

• The convoy travelled from just outside Swansea Port on the A483 through the Mynydd y Gwynt site access with minimal disruption to other road users on the network.

• No additional constraint locations to those highlighted in the Collett report were identified during the test run. It is highlighted that the test run was undertaken on a highly robust basis combining a simultaneous length test and width test where in fact, individual loads would be abnormal only in width OR length.

• No significant queuing time of vehicles was observed. However, to reduce queuing times, the convoy successfully pulled over at various locations to allow following traffic to pass. In practice, a series of locations where loads can safely pass or where loads can pull over has been developed and is provided in the Strategic Traffic Management Plan (“TMP”) report undertaken for the development.

13.115 The test run identified the following requirements:

• mitigation as identified in the Collett report and subsequent WYG swept path assessments at various constraint locations;

• trimming of tree canopy and side vegetation in the verge at various locations along the route;

• use of advanced police escorts to ensure that all vehicles are held back from roundabout arms, junctions and constraint points to reduce the potential conflict with loads; and

• identification and confirmation of the lay-by and hold point locations for use by the convoy during delivery to allow vehicles to pass the convoy and give abnormal load drivers their required rest period and operational flexibility.

13.116 Mynydd y Gwynt Limited and SSE Renewables instructed WYG to combine the results of the test run with the traffic management measures developed through discussions with the WG. This forms the basis of the TMP document which accompanies this application.

13.117 The TMP principally outlines the traffic management requirements of moving the abnormal load and its potential impact on the operation of the road network. It also covers the safety and incident management for all turbine loads.



General Traffic management plan

Proposed Management Measures

13.118 This chapter introduces a number of traffic management measures that could help reduce the impact of the abnormal load convoys and general deliveries. These measures are currently presented as indicative to be confirmed with the relevant local and trunk road authorities and police closer to the time.

13.119 More detailed issues relating solely to the transport of the abnormal loads can be found in the detailed TMP accompanying the application.

13.120 All deliveries would be undertaken at appropriate times with the aim to minimise the impact on the trunk and local road network.

Advance Warning Signage

13.121 Advance warning signs would be installed on the approaches to the affected roads network. Temporary signage advising drivers that abnormal loads will be operating would be erected at strategic locations along the full length of the route from Port of Entry to site. Signs such as the example shown in Sign 13.1 would be installed to help assist drivers.

Sign 13.1: Indicative Information Sign

13.122 The purpose of this type of signage is to help improve driver information and allow drivers of oncoming traffic to consider proceeding to the nearest convenient passing bay, or breaking their journey until the convoy has moved on.

13.123 To further improve driver information, it is suggested that Variable Message Signs (“VMS”), operated by the Highways Agency, are used to warn drivers of abnormal loads operating on the trunk road sections of the route. This would display advance driver information and would allow drivers to consider alternative routes if possible.



Pedestrian Warning Signage

13.124 Temporary pedestrian warning signs should be erected within the urban areas of the route to alert pedestrians and those parking cars of the proposed loads. Signs such as the example shown in Sign 13.2 could be installed.

Sign 13.2: Indicative Pedestrian Information Signage

13.125 The time and date section of the sign could be written in marker pen to allow re-use of the sign during the life of the project.

13.126 The signs would be placed at the major turns within the urban areas and fixed by means of cable ties (or similar) to existing street furniture.

Public Information

13.127 Information on the movement of abnormal load convoys should be provided to local media outlets to help assist the public. Information could be provided to local newspapers and radio stations, which may include:

• Cambrian News (Aberystwyth Edition);

• Bay Radio;

• Radio Ceredigion; and

• BBC Mid Wales Aberystwyth.

13.128 Information would relate to expected vehicle movements from Swansea Port through to the site accesses. It is hoped that this level of information will make residents aware of convoy movements and help reduce any potential conflicts.

13.129 WYG has suggested that the developer produces a local newsletter for distribution to properties along the most affected sections of the proposed access routes, advising of convoy movements and the measures put in place to ensure the safe and efficient operation of the road network.



Transport for Alternative Turbines

13.130 Indicative turbine tower designs from Vestas for the V105 show no increase in V105 turbine base size over the V90 base. This is due to the lower hub height and shorter tower with a lower centre of gravity, despite the increase in swept area, giving a similar kinematic envelope for the tower sections. The number of tower loads is therefore likely to be similar.

13.131 The number of AIL movements for the new Vestas V105 will increase by one delivery per turbine, as the V105 nacelle is shipped without the drive train installed to reduce weight. The drive train itself will be considered as an AIL due to its weight.

13.132 AIL transport will be a critical issue prior to selection of the final turbine manufacturer for obvious reasons. Currently, based on a 2019 earliest grid connection, turbine selection may not be finalised until 2017/8. There may be significant changes to the highway network in the next four to five years, meaning a detailed transport assessment of the candidate turbines will be required during the turbine selection process by both developer and supplier. Detailed discussions and permissions will be sought with the relevant transport authorities in due course.

13.133 New technology may also have an impact on AIL deliveries. One major manufacturer has introduced two part blades for one of their turbine models and other manufacturers may adopt similar ideas to simplify blade delivery. Self-erecting turbines are also being developed to reduce the size of cranes required for turbine erection.

Summary & Conclusions

Summary

13.134 WYG has been commissioned by Mynydd y Gwynt Limited to undertake a TA of the transport issues associated with the development of the proposed 27 turbine Mynydd y Gwynt Wind Farm over approximately 584 hectares of the Sweet Lamb Rally Complex, at Y Foel, near Llangurig, Powys.

13.135 Existing traffic data has established a base point for determining the impact during the construction phase and factored to future levels to reflect the impact of construction traffic on the local road network.

13.136 The maximum traffic impact associated with construction of the wind farm is predicted to occur in month 6 of the construction programme. During this month, an average of 80 HGV movements are predicted per day and it is estimated that there will be a further 52 car and light van movements per day to transport construction workers to and from the site.

13.137 The impact of the development on overall road capacity has been examined and is deemed to be not significant in capacity terms.

13.138 The construction traffic will result in a temporary increase of traffic flows within the study area. During the construction of the wind farm the associated traffic impacts are predicted to be greatest on the section of the A44 between A470 and the site access junction.

13.139 A review of the local road network was undertaken was undertaken to assess the feasibility of transporting turbines to the development site.



13.140 No significant capacity issues are expected on any of the roads within the study area due to the additional construction traffic movements associated with the development.

Conclusions

13.141 The assessment has clearly identified the following:

• the impact of construction traffic on the surrounding road network is short lived and not significant;

• that the surrounding road network has sufficient capacity to accommodate the temporary construction traffic;

• that the construction phase of the project will generate the highest level of traffic;

• that the route from the Port of Entry at Swansea is suitable for turbine delivery; and

• that a traffic management plan is required to control construction traffic in the interests of road safety and efficiency.

References

Ceredigion Unitary Development Plan (Ref-13-001)

Welsh Assembly Government, (2007). Planning Policy Wales, Technical Advice Note 18: Transport. (Ref-13-002)

Institute of Environmental Management Assessment (“IEMA”) Guidelines for the Environmental Assessment of Road Traffic (Ref-13-003)

‘Route Access Survey’ undertaken by Collett Transport, 2010 (Ref-13-004)

DECC, (2011) Overarching National Policy Statement for Energy (EN-1). (Ref-3-009)

Welsh Government, Planning Policy Wales, Edition 6 – February 2014. (Ref-3-015)

Powys Unitary Development Plan (Ref-3-043)

CHAPTER 13 – TRANSPORT ASSESSMENT Introduction … · · 2016-04-28CHAPTER 13 – TRANSPORT...

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