St Austell Transport Strategy Development
Appendix D – A390 Modelling Technical Note
May 2017 Technical Note
Project: A390 St Austell Corridor Study Project No.: EDG0534-TN001 Client: Cornwall Council Subject: Technical Note – A390 St Austell Corridor Micro-simulation Model Summary Revision: V1.1 Originator: LM Date: 03/06/2016 Checked by: RC Date: 06/06/2016 Authoriser : RC Date: 06/06/2016
1 INTRODUCTION
1.1 CORMAC Solutions (CSL) has been commissioned by Cornwall Council (CC) to develop a micro-simulation model of the A390 St Austell corridor; to allow detailed testing, and assessment, of the future developments and network improvements proposed in St Austell.
1.2 An existing strategic model of St Austell has been developed by WSP|PB, using SATURN. The modelling results highlighted capacity issues with the Local Plan and Transport Strategy implemented in 2030.
1.3 The strategic nature of SATURN means that there are limitations when considering the A390 St Austell corridor, particularly the interaction and performance of congested sections of corridors and junctions. Where capacity issues are identified more detailed modelling and assessment is required.
1.4 Due to the complex nature of the highway network under assessment, a micro- simulation model was required in order to assess the different types of junctions within the study area, identify problems within a reasonable degree of accuracy and to produce a controlled and accurate base model to then test the proposed developments and highway proposals, and Transport Strategy against.
1.5 The A390 St Austell corridor micro-simulation model has been developed using PTV VISSIM, version 8. The model study area is shown in Figure 1.1.
1.6 The detailed microsimulation tool, VISSIM, was considered to be capable of achieving the aims noted above and also evaluating the impact of mitigation measures over the study area.
1.7 VISSIM is a microscopic, behaviour based multi-purpose traffic simulation program developed by PTV. The program uses a psychophysical car following model developed by Wiedemann and a related lane changing model originally designed by Sparrman.
1.8 In addition to modelling various different types of junction, the program can also analyse other typical traffic operations, such as bus stops/ public transport routes, road user behaviour under differing conditions, such as school peaks, and the effect of various network constraints such as traffic control, lane configuration, traffic composition etc.
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1.9 The ability to combine VISSIM with other external software such as VAP (Vehicle Actuated Program), PC SCOOT or PCMOVA, to name a few, means that complex signalised junctions can also be modelled to a fine degree of accuracy, replicating the on-street methods of control.
1.10 The A390 St Austell corridor study area has a mixture of signalised junctions currently operating under MOVA or VA control. 1.11 This short Technical Note will summarise the construction of the base model build, development of the 2030 future year model, and, a summary of the 2030 model performance.
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2 2014 BASE MODEL
2.1 The A390 St Austell corridor model study area covers from the A390/ A391 Cuddra signals in the east, to A390/ A3058/ B3274 Edgcumbe Triangle in the west.
2.2 Traffic data for the A390 St Austell corridor study was collected in July 2014. The data collection included: Manual Classified Turning Counts (MCTC) at 17 junctions; Queue Lengths at 17 junctions; Automatic Traffic Counts (ATC) at 10 sites; Pedestrian Counts at 7 sites; and Journey Times (Strat-E-gis data).
2.3 The traffic data collected was then used to develop the 2014 base year model, with the following weekday peak periods assessed: AM Peak Period: 07:00 – 10:00 PM Peak Period: 15:00 – 18:00
2.3.1 The following vehicle classes have been modelled:
Cars; Light Goods Vehicles (LGV); Other Goods Vehicles 1 (OGV1); Other Goods Vehicles 2 (OGV2); Motorcycles (MCY); and Pedal cycles (BCY).
2.4 Each vehicle class has its own desired speeds, gap acceptance and behaviour parameters coded to represent realistic on-street conditions.
2.5 Public transport routes and stops have also been coded into the model. All this data was collected from ‘Traveline South West’ website which provides every public transport company’s timetables that serve the St Austell area.
2.6 Pedestrians are also included in the base model, using the pedestrian data collected at all the controlled crossing points at junctions and along the A390.
2.7 The model also uses Dynamic Assignment, which is zones and matrix based, and allows for route choice within the model. The Matrices were created from the manual counts collected; no origin-destination (O-D) data was available. Model zone plan is shown in Figure 2.1.
2.8 MOVA dataset (.mds files) were taken from the on-street traffic signal controllers, and existing traffic signals data and specifications for VA junctions were used to replicate the on-street control of the traffic signal junctions within the model study area. This is listed in Table 2.1.
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Signals Signal Junction Name Notes: Site No. Control J1 A390/ A391 Cuddra S416 MOVA J2 A390/ Bucklers Lane S405 MOVA A390/ Holmbush Arch J3 S408 MOVA Road Planned upgrade to J4 A390/ Daniels Lane S406 VA MOVA, was awaiting Tesco redevelopment Ped Daniels Lane P104 Pelican No loops - MVD Mount Charles/ Clifden J6 S409 VA Rd/ Victoria Rd Ped A390 Polmear Road S427 Toucan Crossing linked to J7 J7 A390/ Duporth S427 MOVA J9 A390/ Sawles Road S420 VA Dual staggered Puffin A390 Penwinnick Road crossing with VA + SDE. Ped P114 Puffin Eastbound Staggered crossing not linked. A390 Penwinnick Road Ped P124 Puffin Westbound A3058/ B3274 J11 S407 MOVA Edgcumbe Triangle Table 2.1 – Existing St Austell Traffic Signals
2.9 The A390 St Austell 2014 Base model was then calibrated and validated against the turning counts, queues and journey times collected in July 2014.
2.10 The calibration and validation results exceeded the validation criteria required for the base model to be classed ‘fit for purpose’ and to be used to test and develop future year scenarios.
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3 2030 FUTURE YEAR MODEL
3.1 The 2014 base model has been used to develop the 2030 future year scenario. Table 3.1 details the composition of the 2030 scenario.
Scenario Developments Network 2014 Base 2014 Base year flows. 2014 base year network. 2030 Full As 2014 Base + As 2014 Base + Development Land North of Seaways, Holmbush Road Dev. Menear Road Signalised Junction Land off Mountside Road, Par Toucan crossings on A390 Land East of Mount Cresent, Holmbush Road and Par Charlestown Road approaches Holmbush Road dev to Mount Charles roundabout Porthpean Road Phase 1,2 & Existing Clifden Rd/ Mount 3 Charles Rd VA signals Old Bus Depot, Eliot Road upgraded to MOVA Pentewan dev. (Morrisons) Reconfiguration of Duporth Higher Trewhiddle Farm signals – opening up right Carlyon Bay dev. turn, heading north on West Carclaze dev. Porthpean Rd, continuous two lanes westbound from Mount Charles roundabout to ASDA roundabout Existing A390 Trevanion Road/ Sawles Road VA signals upgraded to MOVA + pedestrian stage Pentewan Dev. single roundabout replacing double mini-roundabout and signalisation of B3273 Pentewan Rd/ Mc Donalds/ B&Q junction Edgcumbe Triangle roundabout, existing 4 arm VA signals replaced with 3 arm signals and upgraded to MOVA Higher Trewhiddle Fm Dev. single lane roundabout access Full Pentewan Link Road (PLR) – roundabout access connecting PLR to B3273 Pentewan Road. PLR including access to Edgcumbe Triangle roundabout. Table 3.1 – 2030 Full Development Model Assumptions
3.2 The 2030 Full Development scenario includes all major developments, of all types, that either have planning consent or that are expected to receive planning consent.
3.3 Developments accesses that fall inside of the model study area have been coded into the model with an allocated zone, and developments that fall outside of the model study area but are expected to impact on traffic flows along the A390 corridor are also included and trips are loaded onto the appropriate zones.
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3.4 Background growth to existing trips has not been applied in the 2030 scenario.
3.5 Several CC highway scheme improvements are also included, as listed in Table 3.1 – this forming part of the Transport Strategy for St Austell. This includes a form of UTC for the A390 Holmbush Road signalised corridor, junction upgrades to facilitate the expected growth, and walking and cycling improvements to promote sustainable modes of transport.
3.6 All new and upgraded signalised junctions operate under MOVA control to optimise junction control and capacity, and to reflect how the junctions will operate once implemented on-street. Linked MOVA is in operation where signals are in close proximity to another set of signals, this to achieve a smoother flow and green wave along the corridor, where possible.
3.7 As part of the Transport Strategy promoting sustainable modes of transport, a modal shift assumption to development trips has not been applied in the initial 2030 matrices, but modal shift assumption target percentage to be agreed and applied before final modelling results are collected.
3.8 It has been assumed that the Edgcumbe Triangle scheme will provide a link onto the Pentewan Link Road (PLR), with the link road starting at the Trewhiddle roundabout access. However, this is subject to change with the possibility of the Edgcumbe scheme becoming the starting point of the Pentewan Link, or alternatively no link at all to the Trewhiddle development/ Pentewan Link.
3.9 Initial 2030 modelling has been conducted; a brief summary of the model performance can be found in section ‘4: Summary’.
3.10 A full ‘Model Development Report (MDR)’ will be issued shortly; detailing the 2030 model build, future developments and Transport Strategy assumptions, network performance, and any further assessments required.
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4 SUMMARY
4.1 Initial modelling of the 2030 Full Development scenario has indicated that the Transport Strategy provides sufficient capacity for the anticipated growth assumed for St Austell.
4.2 The UTC proposal for the A390 Holmbush corridor section will help prioritise and protect the strategic vehicular flow. This will have an impact on side road queues, but in the long term reduce the attraction rat-running.
4.3 The proposed ‘Pentewan Link Road’ will reduce trips using the A390/ B3273 Pentewan Roundabout, with traffic from the west heading towards Mevagissey, and the south, using the link road, and vice versa trips from the south heading west using the link road.
4.4 The Transport Strategy also proposes to promote and provide enhanced sustainable modes of transport on the A390 corridor. However, the initial 2030 modelling does not include a modal shift assumption. It is expected that with some development trips shifted to sustainable modes, such as walking, cycling and public transport, a reduced number of vehicular trips will enter the network, therefore improving capacity further.
4.5 The indicative costs for the improvements to the A390 corridor as part of the St Austell Transport strategy are detailed below
Ref Scheme Name Details/ Description Initial Programme Estimate* Year(s) £000’s 1 St Austell A390 Urban The proposal is to link these signals under a Traffic Control computer controlled UTC system that will optimise the throughput of traffic on the A390 in peak periods, thereby improving journey times and reliability. This system has the ability to implement different route strategies throughout the day and during 700 2016-2019 events, plus provide priority for buses and emergency vehicles through the use of transponders. The UTC system comprises advanced computer software, enhanced signal controllers with communications links and additional detection equipment.
2 Bucklers Lane Traffic Optimise existing traffic signal layout to Signals improve efficiency and tie in with A390 UTC 80 2016-2019 Management Strategy
3 Daniels Lane Traffic Optimise existing traffic signal layout to Signals improve efficiency and tie in with A390 UTC Management Strategy, including possible 150 2016-2019 relocation of bus stops and provision of improved pedestrian crossing facilities
4 Mount Charles Provision of TOUCAN crossings on 2 arms 200 2016-2019 Roundabout 5 Porthpean Rd Signals Substantially amend existing traffic signal junction to reintroduce banned right turn and provide greater throughput on the 800 2016-2019 westbound link to Asda roundabout
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Ref Scheme Name Details/ Description Initial Programme Estimate* Year(s) £000’s 6 Sawls Rd Optimise existing traffic signal layout to improve efficiency and tie in with A390 UTC Management Strategy, including provision of 200 2016-2019 cycle facilities on North/ South arms and improved pedestrian crossing facilities 7 Edgcumbe Triangle Major Junction improvement – closure of south east arm of current crossroads, and provision of major new junction on A390. 2250 2016-2019 Options under consideration inc large diameter roundabout or new traffic signal junction. 8 Trewiddle Link Completion of approx. 600m of the Trewiddle Link Rd and provision of new 2750 2019+ junction on B3273 Pentewan Rd 9 10 TOTAL 7130 * Note: these initial estimates are based on typical costs of similar schemes. The schemes are at early stages of development, therefore no detailed consideration of costs associated with stats diversions, land acquisition, any site specific construction issues/ constraints, traffic management have been undertaken. Table 4.1 – Indicative Scheme Costs for A390 St Austell Transport Strategy
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FIGURES
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