St Austell Transport Strategy Development

Appendix B – Transport Strategy Review

May 2017

St Austell Town Framework

Transport Strategy Review

EDG0362-R001 Revision No. 01 Date: 12/12/2013

CORMAC Consultancy

CORMAC Western Region,

Radnor Road, Scorrier, Redruth, Cornwall, TR16 5EH.

St Austell Town Framework

Transport Strategy Review

Issue & Revision Record

Revision Date Originator Checked Authorised Purpose of Issue Nature of Change

01 12/12/13 AJA / JF LM AJA First Issue

If you would like this report in another format, please contact

CORMAC Solutions Ltd Head Office Castle Canyke Road Bodmin Cornwall PL31 1DZ

Prepared by Tel: 01872 323 313 Engineering Design Group Email: [email protected] www.cornwall.gov.uk/cormac

This document has been prepared for the titled project or named part thereof and should not be relied upon or used for any other project without an independent check being carried out as to its suitability and prior written authority of Cormac Solutions Ltd being obtained. Cormac Solutions Ltd accepts no responsibility or liability for the consequences of this document being used for a purpose other than the purposes for which it was commissioned. Any person using or relying on the document for such other purposes agrees, and will by such use or reliance be taken to confirm his agreement to indemnify Cormac Solutions Ltd for all loss or damage resulting therefrom. Cormac Solutions Ltd accepts no responsibility or liability for this document to any party other than the person by whom it was commissioned.

CORMAC Solutions Ltd Head Office, Castle Canyke Road, Bodmin, Cornwall, PL31 1DZ

CONTENTS

1 INTRODUCTION 1 1.1 Overview 1 1.2 Project Scope 1 1.3 Report Structure 1 2 STRATEGIC TRANSPORT MODEL REVIEW 2 3 WEST CARCLAZE DEVELOPMENT TRAFFIC IMPACT 3 4 REVIEW TRANSPORT SCHEME PROPOSALS 5 5 REVIEW PUBLIC TRANSPORT PRIORITY MEASURES 6 6 EDGCUMBE TRIANGLE ANALYSIS 7 7 TREWHIDDLE FARM LINK ROAD ANALYSIS 8 8 CONCLUSION 9

1 INTRODUCTION

1.1 Overview

1.1.1 CORMAC Solutions Ltd (CSL) has been commissioned by Cornwall Council (CC) to review the St Austell Town Framework Transport Strategy in light of potential reductions in housing numbers proposed in the emerging Local Plan.

1.1.2 This review does not include detailed strategic or micro-level remodelling due to limitations in both timescale and budget. The review therefore makes a number of assumptions relating to potential development traffic generation, distribution and assignment.

1.2 Project Scope

1.2.1 As agreed with Cornwall Council the project will review the following specific aspects of the previous Town Framework Transport Strategy:

 Review strategic transport model in light of current consultation options for future growth (2,000 proposed residential dwellings of which 1,800 is already permitted);

 Manually reassign traffic flows to consider the potential impact of the West Carclaze planning application;

 Review existing transport strategy measures and propose new measures where appropriate;

 Review any opportunities for bus priority measures;

 Review developer proposed Edgcumbe Triangle improvement and consider pedestrian accessibility issues; and

 Assess impact of an estate road running through the Trewhiddle development in relieving Edgcumbe Triangle.

1.3 Report Structure

1.3.1 The report structure will follow the scope of work above.

EDG0362 R001 1 December 2013

2 STRATEGIC TRANSPORT MODEL REVIEW

Introduction

2.1.1 A review of the St Austell Area Strategic Transport Model has been undertaken to understand any limitations in the model that may impact upon future transport modelling in the area.

2.1.2 The original St Austell SATURN traffic model was developed by Mott MacDonald for Cornwall County Council in 2000/2001 to assess route improvement options on the A391 corridor. The model was then updated by Mott Macdonald in 2004 and by Mouchel in 2007. The Mouchel update did not include additional survey data and therefore the most recent data used in the model was collected in 2003. Since the 2003 data was collected the A30(T) Bodmin to Indian Queens Improvement opened to traffic, visitor numbers at the Eden Project have declined, and St Austell town centre was redeveloped with the opening of White River Place.

2.1.3 As part of the Eco-Communities work Parsons Brinckerhoff updated the model to a base year of 2010 using additional roadside interview survey data, traffic count and journey time data. The model is now WebTAG compliant.

Model Calibration and Validation

2.1.4 The Local Model Validation Report (LMVR), published by Parsons Brinckerhoff in September 2011 (reference WHV285300DL) concludes that the model accurately represents the existing traffic situation within the study area. However, it should be noted that calibration of the PM peak model did fall below the DfT threshold of 85% of link flows being within a specified threshold and only achieved 80% of links within the thresholds. Overall calibration is achieved because the AM peak achieved a 97% calibration level. This does raise some potential questions regarding the validity of the PM peak model but discussions with Parsons Brinckerhoff suggest that the principal road network within the study area achieved appropriate calibration levels.

Network Structure

2.1.5 Reviewing the network structure within the Town Framework study area confirms that the network is appropriate for determining traffic impact associated with development proposals.

EDG0362 R001 2 December 2013

3 WEST CARCLAZE DEVELOPMENT TRAFFIC IMPACT

Introduction

3.1.1 Cornwall Council is currently progressing a planning application for the West Carclaze Eco-Communities development, which will comprise approximately 1,500 residential dwellings plus associated community facilities. Cornwall Council is now leading on this project as EcoBos, the Eco-Communities developer has put its plans on hold due to the current financial climate and uncertainty over the emerging Local Plan.

3.1.2 CORMAC Solutions Limited has been commissioned by Cornwall Council’s Planning Service to produce the Transport Assessment and Travel Plan in support of this planning application but this work will not commence until February 2014. Therefore, an estimate of the potential development impact on St Austell has been produced as part of this review.

3.1.3 At this stage the access strategy for the West Carclaze development has not been finalised as Cornwall Council has only recently commissioned the master planning project. Savills have been commissioned to undertake this work but the emerging master plan will not be identified until early 2014. However, it is assumed that the development will access the highway network onto the A391 in the vicinity of Carluddon and the B3274 in the vicinity of Carthew. Figure 3.1 shows the West Carclaze development area and potential access strategy.

Trip Generation, Distribution and Assignment

3.1.4 Until the development mix is finalised it is not possible to develop an accurate trip generation for the West Carclaze site. However, assuming a development in the order of 1,500 residential dwellings Table 3.1 summarises potential trip generation.

Trip Rate Trip Numbers Time Arr. Dep. 2 Way Arr. Dep. 2 Way 08:00 to 08:59 0.16 0.57 0.73 240 855 1,095 17:00 to 17:59 0.39 0.25 0.64 585 375 960

Table 3.1 Assumed Residential Trip Rates – West Carclaze

3.1.5 Table 3.1 identifies that the West Carclaze development could generate in the order of 1,000 two way trips per hour in the peak hours. Not all of this traffic will travel to St Austell as some will head north to the A30(T) to access other towns in the area. As the detailed trip distribution work has not yet been undertaken for the West Carclaze development assumptions have been made as to where the vehicle trips will travel to/from. These assumptions are summarised in Table 3.2.

EDG0362 R001 3 December 2013

Origin / Destination Assumed Percentage Two Way Trips A30(T) East 20% 200 A30(T) West 20% 200 A390 East 10% 100 A390 West 20% 200 St Austell 30% 300

Table 3.2 Assumed Residential Trip Distribution and Assignment

3.1.6 Based on the assumed traffic volumes identified in Table 3.2 it is possible that approximately 400 trips to and from the West Carclaze Development will route northwards onto the A30(T) to access towns such as Newquay, Bodmin, Wadebridge, Launceston and to travel further afield to Devon.

3.1.7 This would result in approximately 600 trips per hour travelling southwards and therefore impacting on the St Austell highway network.

3.1.8 For journeys having origins or destinations along the A390 to the west of St Austell, ie trips to or from Truro or further afield, the routing to the West Carclaze development could be split between the B3274 through Carthew and Ruddlemoor to reach St Austell and then Truro Road to reach the A390 or via the A391, Treverbyn Road, Slades Road and onto the A390 near Mount Charles.

3.1.9 For journeys having origins or destinations along the A390 to the east of St Austell, ie, trips to and from Par, Liskeard, etc, routing south along the A391 would be the quickest route.

3.1.10 For journeys having origins and destinations in St Austell the routing could be the B3274 through Carthew and Ruddlemoor, or Treverbyn Road onto Slades Road or Tregonissey Road.

3.1.11 Figure 3.2 shows potential two-way flow increases on the major roads in St Austell based on the above assumptions.

Potential Traffic Impact

3.1.12 Based on the junctions that were previously identified in the Town Framework Transport Strategy the West Carclaze development is likely to increase traffic impact at:

 A3058 Edgcumbe Road / B3274 Truro Road

 A390 / B3273 Penwinnick Road / Pentewan Road

 Treverbyn Road / Tregonnissey Road / Slades Road / Carclaze Road

 Slades Road / Sandy Hill / Clifden Road / Polkyth Rad

3.1.13 However, with an overall reduction in traffic associated with a lower growth scenario for St Austell impact may be no worse than previously identified.

EDG0362 R001 4 December 2013

4 REVIEW TRANSPORT SCHEME PROPOSALS

4.1.1 The principal transport schemes proposed in the St Austell Town Framework Transport Strategy are:

 A3058 to A390 Coyte Farm Link Road

 A3058 Bus Gate

 A390 / B3273 Penwinnick Road / Pentewan Road Double Mini-Roundabouts

 A390 Holmbush Road Traffic Signal Co-ordination

 Treverbyn Road / Tregonnissey Road / Slades Road / Carclaze Road

 Slades Road / Sandy Hill / Clifden Road / Polkyth Rad

4.1.2 The locations of these schemes are shown on Figure 4.1.

4.1.3 Having reviewed a previously developed SATURN scenario for a lower level of development than the original Town Framework allocation it can be concluded that the improvement schemes listed above would still be required. However, it needs to be considered that the scenario that has been reviewed still represents greater development growth than the current Town Framework proposals. The capacity values calculated in the modelled scenario are such that even with some further reduction in traffic there is likely to be a need for the above improvements. It is not proposed, at this stage, to undertake specific SATURN modelling to determine the specific impacts of the current Town Framework allocation.

EDG0362 R001 5 December 2013

5 REVIEW PUBLIC TRANSPORT PRIORITY MEASURES

5.1.1 The previously developed Town Framework Transport Strategy was limited in scope when considering public transport priority measures. The road network in St Austell is constrained by adjoining development and without large scale acquisition and possible demolition of properties there is limited scope to provide bus priority measures.

5.1.2 Figure 5.1 shows potential key public transport routes in St Austell, which may or may not be currently served. At key locations on this public transport network a further review of road space has been undertaken to determine whether or not public transport priority measures can be created. The locations considered are listed below:

 A390 Edgcumbe Road / B3274 Truro Road

 B3274 Truro Road / Trinity Street

 Trinity Street / South Street

 High Cross Street / Carlyon Road / Palace Road

 East Hill / King’s Avenue / Alexandra Road

 Treverbyn Road / Tregonnissey Road / Slades Road / Carclaze Road

 Victoria Road / Woodland Road

 Slades Road / Sandy Hill / Clifden Road / Polkyth Rad

 A390 Cromwell Road / Porthpean Road

 A390 Polmear Road / Holmbush Road – Mount Charles Roundabout

 Bethel Road / Bucklers Lane

 A390 Holmbush Road / Daniels Lane

 A390 Holmbush Road / Bucklers Lane

 A390 Holmbush Road / A391

5.1.3 An engineering review of the above locations identified no real scope for introducing bus priority measures unless the existing network hierarchy is to be changed and some locations become public transport corridors with private traffic forced onto other routes. Such an approach would be similar to that taken in Camborne, Pool, Redruth (CPR) where the A3047 is to be downgraded in a number of locations to facilitate better walking, cycling and public transport provision. The difference between St Austell and CPR is that St Austell doesn’t have viable alternative routes for use by private vehicular traffic.

EDG0362 R001 6 December 2013

6 EDGCUMBE TRIANGLE ANALYSIS

6.1.1 As part of the Coyte Farm development proposals to the west of St Austell the applicant’s consultant has proposed a reconfiguration of the Edgcumbe triangle junctions to increase capacity. Figure 6.1 shows an aerial photograph of the existing junction arrangement.

6.1.2 The northern junction in the triangle is traffic signal controlled. This junction currently experiences capacity problems. The junction is also constrained geometrically and the footway provision is limited. The south-west and south-east junctions are both priority junctions that feed traffic into the traffic signal controlled junction. Capacity at these junctions is not a significant issue.

6.1.3 The consultant has proposed, see Figure 6.2, that certain turning movements are changed at the two priority junctions to restrict the number of right turning manoeuvres at the traffic signal controlled junction. The rationale being that right turning vehicles currently obstruct the straight ahead movements at the traffic signal controlled junction. While this proposal does have merits the one right turn movement at the traffic signal controlled junction that remains is the right turn from Truro Road to Edgcumbe Road, towards Trewoon. This turning movement is the largest right turn manoeuvre at the junction and therefore would require the opposing movement from the A390 to be held on red to allow it to clear. The issue with this is the movement from the A390 now incorporates traffic from the St Austell side of the junction who have been forced to right turn at the south-west priority junction so that they can travel ahead to Truro Road. This potentially increases the conflict for one of the largest turning manoeuvres at the traffic signal controlled junction. The other issue with the proposed layout is traffic travelling from Trewoon who wish to turn right towards Truro now have to use the south- east priority junction, which was previously used only by traffic travelling to St Austell. This introduces a crossing manoeuvre on the A390 that wasn’t previously there, which would be expected to introduce delays.

6.1.4 The critical junction within the three junction network is the traffic signal controlled northern junction and this isn’t being improved sufficiently to justify the other changes to the junctions, which will complicate traffic movements in the area.

Pedestrian Accessibility

6.1.5 Pedestrian accessibility at the Edgcumbe Triangle, particularly the traffic signal controlled northern junction is poor due to narrow footways in the area. Studies have been undertaken previously to examine the potential for installing controlled pedestrian crossings but there is insufficient room to install the equipment notwithstanding the negative impact such proposals would have on the capacity of the junction.

EDG0362 R001 7 December 2013

7 TREWHIDDLE FARM LINK ROAD ANALYSIS

7.1.1 The Trewhiddle Farm development cell proposed within this iteration of the Town Framework offers the potential for an east-west link road connecting the A390 in the vicinity of St Mewan with the B3273 Pentewan Road. This road could enable traffic from the Pentewan and Mevagissey areas that wish to travel to/from Truro to bypass the congested A390 / B3273 Penwinnick Road double mini-roundabout junction.

7.1.2 This would reduce the traffic volumes at the double mini-roundabout by approximately 250 vehicles per hour out of a total inflow of approximately 3,000 vehicles per hour. This would represent an 8% reduction at the junction. However, the Trewhiddle Farm development could add more traffic than this to the network, which would negate any improvement.

7.1.3 Assuming a development of approximately 800 residential dwellings, Table 7.1 summarises the potential peak hour vehicle trip generation for the development.

Trip Rate Trip Numbers Time Arr. Dep. 2 Way Arr. Dep. 2 Way 08:00 to 08:59 0.16 0.57 0.73 128 456 584 17:00 to 17:59 0.39 0.25 0.64 312 200 512

Table 7.1 Assumed Residential Trip Rates – Trewhiddle Farm

7.1.4 Assuming the trip distribution summarised in Table 3.2, 60% of the development trips could pass through the A390 / B3273 double mini-roundabouts. This would equate to approximately 300-350 trips per hour. This potentially exceeds the volume of traffic that could be diverted through provision of the road.

7.1.5 The predicted traffic flow increase at the A390 / B3273 double mini-roundabout junction would still require some form of improvement to accommodate these increases.

EDG0362 R001 8 December 2013

8 CONCLUSION

8.1.1 The St Austell road network currently experiences congestion, during peak periods, in a number of locations. The previous Town Framework Transport Strategy transport modelling identified a number of locations where improvements would be required to accommodate growth in St Austell.

8.1.2 This report has considered the need for these improvements if a lower development growth level was to be promoted. Detailed re-modelling of the transport network has not been undertaken as part of this project and therefore the conclusions reached need to be treated with some caution but are considered to be robust.

8.1.3 The report has also taken into account the traffic impact of the proposed Eco- Community development at West Carclaze which is currently being promoted by Cornwall Council. This development is likely to add vehicular traffic to a number of locations in St Austell that are currently suffering from traffic congestion.

8.1.4 A review of public transport priority measures has been undertaken and given the lack of parallel / duplicate routes in the town there is little scope for any type of improvement.

EDG0362 R001 9 December 2013

WEST CARCLAZE DEVELOPMENT AREA A391 ROAD IMPROVEMENT

Drawing Title: St Austell Town Framework Transport Strategy Review

West Carclaze Development Location

Scale: Date: Drawing Number: NTS @ A4 10/12/2013 Figure 3.1

Drawn by: Originator: Project Manager: JF JF AJA

Revision: Nature of Revision: - -

© Crown copyright and database rights 2013. Ordnance Survey 100049047. This drawing is Copyright. It should not be relied on or used in circumstances other than those for which it was originally prepared and for which Cornwall Council was originally commissioned. Cornwall Council accepts no responsibility for this drawing to any party other than the person(s) by whom it was commissioned. B3274 A391 +100 +500

+200 +300

+100 +100 +100 A390 +150 A3058 +50 +150 +100 +100 +50

+50 +100 +50

+100

+200 Drawing Title: St Austell Town Framework Transport Strategy Review A390 West Carclaze Development Peak Hour Traffic Flow Increases B3273 Scale: Date: Drawing Number: NTS @ A3 03/12/2013 Figure 3.2

Drawn by: Originator: Project Manager: DB LM AJA

Revision: Nature of Revision: - -

TREVERBYN RD/ TREGONISSEY RD/ SLADES RD/ CARCLAZE RD

SLADES RD/ SANDY HILL/ CLIFDEN RD/ POLKYTH RD IMPROVEMENT

A3058 BUS GATE

A3058 TO A390 COYTE FARM LINK A390 HOLMBUSH ROAD TRAFFIC ROAD SIGNAL CO-ORDINATION

A390/ B3273 PENWENNICK RD/ PENTEWAN RD IMPROVEMENT Drawing Title: St Austell Town Framework Transport Strategy Review

Transport Strategy Proposals

Scale: Date: Drawing Number: NTS @ A3 11/12/2013 Figure 4.1

Drawn by: Originator: Project Manager: JF JF AJA

Revision: Nature of Revision: - -

11 8 14 2 4 13 12 7 10 3 5 1 9

POTENTIAL AREAS x FOR BUS PRIORITY

Drawing Title: St Austell Town Framework Transport Strategy Review

Potential Bus Network

Scale: Date: Drawing Number: NTS @ A3 03/12/2013 Figure 5.1

Drawn by: Originator: Project Manager: JF JF AJA

Revision: Nature of Revision: - -

Drawing Title: St Austell Town Framework Transport Strategy Review

Edgcumbe Triangle Existing Layout

Scale: Date: Drawing Number: NTS @ A4 10/12/2013 Figure 6.1

Drawn by: Originator: Project Manager: JF AJA AJA

Revision: Nature of Revision: - -

Right Turn retained at this location, therefore capacity issue at this junction not resolved.

Permitting Right Turn towards A390 Truro introduces additional turning manoeuvre at this junction. This would impact negatively on capacity.

Permitting Right Turn towards Truro Road introduces additional turning manoeuvre at this junction. This would impact negatively Drawing Title: on capacity. St Austell Town Framework Transport Strategy Review

Edgcumbe Triangle Proposed Layout

Scale: Date: Drawing Number: NTS @ A4 10/12/2013 Figure 6.2

Drawn by: Originator: Project Manager: JF AJA AJA

Revision: Nature of Revision: - -