Agenda item

Modelling and Traffic Update


The Assistant Director LTC introduced the report and commented that the briefing note referenced supplementary consultation, and although this had been reported by a newspaper in Kent, the dates or consultation itself had not yet been confirmed by HE. She added that the views in the technical note were the views of Thurrock Council, and had not been checked with HE, so therefore were subject to change.

The Representative from Peter Brett Associates (PBA) added that the technical note was separated into three sections: an explanation of the cordoned model; a list of requests for HE and Thurrock Council; and next steps/actions to be taken. She began by explaining the cordoned model, which was a section taken from the larger traffic model and only showed the borough of Thurrock. She explained that because of this, it did not show traffic south of the river or the two crossings themselves, so incidents on the crossings could not be tested. She stated that the effect of the Lower Thames Crossing (LTC) could be tested and from this, they could draw conclusions and possible outcomes from bringing the LTC into the highway network. The PBA Representative explained that there was a neutral impact on the local road network, and not much change could be seen after the introduction of the LTC, with only small variation on many local road junctions. She stated that there were adverse impacts on the strategic road network in peak periods after the introduction of the LTC due to induced traffic. She added that this was to be expected in traffic modelling as it showed changes in people’s routes into and out of the borough on the strategic highway due to the LTC. She stated that the largest adverse impacts could be seen on the operation of junctions to the east of the LTC such as the Orsett Cock Roundabout and Manor Way. She added that because of these concerns PBA and Thurrock Council were taking a more detailed look at these junctions in the cordoned model. The PBA Representative stated that beneficial impacts could be seen due to the LTC on local roads such as speed improvements, and reduction of traffic on the current Dartford Crossing, on the A13 west of the LTC, and at junction 30 on the M25, as the LTC provided relief to the network. The PBA Representative summarised the audit of the cordoned model and stated that this was the view of PBA and Thurrock Council, and more investigation was still to be done on the Manor Way junction, and Orsett Cock Roundabout. She added that PBA also wanted to see the effect of the port expansion and Local Plan, as neither of these had been considered within the model.

The PBA Representative then moved on to describe section two of the technical note and the requests that had been made to HE. She described how Thurrock Council and PBA had asked for the model to be updated to include any design changes; the results of consultation; updated freight data and national road forecasts; the updated statutory consultation model; and for the model to include the A13 widening drawings.
The PBA Representative finally moved onto discussing section three of the technical note and the upcoming actions for HE and Thurrock Council. She stated that Thurrock Council were going to provide HE with the A13 widening drawings, to allow the model to be updated. She also stated that HE were being asked to provide more data, as they had completed more surveys than were currently listed on their website. The PBA Representative added that HE were also being asked to include a sensitivity test for the Local Plan. She described how Thurrock would also provide a Tilbury Link Road junction option, as the LTC might include passive provision for this junction in the future. She added that Thurrock were asking HE to reuse the arisings from the tunnel for new housing developments or port expansion. She explained that the Port had also been asked to provide more detail on their planned expansion, and workshops had been requested regarding the Asda Roundabout on the A1089, as the LTC would bring about lots of change to this roundabout, and planned development. The PBA Representative summarised and stated that the Task Force would receive another update if the cordoned model was updated, and if any updates arose out of additional modelling for the Manor Way junction or the A13 east of LTC.

The TCAG Representative began questions and asked how accurate the cordoned model was at predicting real traffic flows in the borough. The PBA Representative replied that the model was based on a ‘typical day’ in March 2016, but there were always traffic variations. She stated that the model was only a tool to test relative change, but met industry standard web-tag guidance. The Assistant Director LTC added that although web-tag was the industry standard, it was known to be relatively outdated, but this could only be updated by the Department for Transport who were not planning an update in the near future. She added that traffic modelling was not an exact science, and most modelling for major schemes did not accurately predict traffic or people’s behaviours. She stated that if the traffic modelling did not work, it could send the project back in the Development Consent Order (DCO) process.

The Resident Representative asked what pricing system had been used to run the traffic model, as the price of the tolls could have an impact on which crossing people used. The PBA Representative replied that the tolls had been run as like-for-like in the traffic model. Councillor Spillman asked if officers and PBA had been surprised at the outcome of the modelling, as it seemed like there were some benefits to the scheme. The Assistant Director LTC replied that traffic modelling was difficult to analyse as the data was from 2016 and therefore out of date. She stated that the Council’s aim now was to update the model, but because roads and traffic changed so quickly, models were always in deficit. She clarified that the modelling could be used to identify mitigation, but that significant housing development and employment factors were not factored in. Councillor Spillman stated that he felt the recommendations in the note were fair and reflected the situation, and felt that adding the A13 widening scheme into the model would be useful. He asked how the Council would ensure that the model’s data was as up to date as possible. The Assistant Director LTC answered that PBA and officers would continue to ask for an updated model from HE, but in the meantime would work on potential ‘pinch points’ such as the Manor Way junction and access to DP World and London Gateway. She added that the Council would be seeking mitigation throughout the process, as well as future mitigation such as a Section 106 agreement stating that when traffic reached a certain level, additional mitigation could be added.

Councillor Mayes asked how often guidelines stated that models should be updated, or if they could be updated on an ad-hoc basis. The PBA Representative responded that guidelines suggested models be updated every five years, but pressure could be put on HE to update sooner as the model was now out of date. Councillor Mayes questioned the Tilbury Link Road as part of the scheme. The Assistant Director LTC replied that the Tilbury Link Road was not a part of the scheme, but provision for future access for the road was a desire of the Port of Tilbury and Thurrock Council, and stated that discussions were taking place with HE to ensure this design happened at a future point. She added that the scheme could only come from HE as the Tilbury Link Road would be funded through the Road Investment Strategy (RIS), and RIS1 was ending in April 2020. She commented that if the Tilbury Link Road was delivered, it would not be until RIS3 in 2025-2030.

Councillor Jefferies asked if the traffic modelling outcomes could change if PBA and Thurrock Council had access to the entire model. He also asked if the modelling data from 2016 had included the A13 widening scheme drawings, as this scheme had already been devised at that point. The PBA Representative replied that HE provided a base and a future model, which considered road capacity with or without the LTC, so the Kent model was not necessary unless Thurrock wished to undertake its own traffic modelling. She added that the future modelling included 2026, 2041 and 2051 and had included the A13 widening scheme, although not in its final design stage.

The Chair asked if the workshop with HE and the Port of Tilbury could include plans for a flyover at the Asda Roundabout to separate local traffic with freight. The Assistant Director LTC commented that this was known as a grade separated roundabout, which was the same design as the Rayleigh Weir. She stated that she had already suggested this to HE, as they were concerned by the impact of the LTC on the Asda Roundabout.

Councillor Muldowney questioned whether it was normal to receive a cordoned model from HE for schemes of this nature. The Assistant Director LTC answered that it was unusual to receive any model from HE as they usually only shared traffic modelling outputs. She clarified that this was the first time HE had shared a model, and the Council had worked hard to enter into a data sharing agreement with HE to be able to have access. She explained that as the Council had entered into the data sharing agreement, they could not share the model as it was classified confidential, but other local authorities had not signed an agreement yet, so did not have access at all. Councillor Spillman then asked if Thurrock could run their own model to have a primary data source, and asked what resources would be necessary to do this. The PBA Representative stated that discussions had taken place regarding building a similar model and if this would be worthwhile, so they could test the effect of new developments, port expansion, and incidents at the crossings. She added that traffic models needed constant updating, and HE would not necessarily believe the results of Thurrock’s modelling. She stated that discussions were still ongoing over this issue, as it could be a useful tool. The Assistant Director LTC added that this would be an expensive project as it could cost hundreds of thousands of pounds.

Councillor Shinnick expressed her concern that HE had not attended a Task Force meeting recently, and asked if they could be invited. The Assistant Director LTC commented that they could be invited to any Task Force meeting, although they would need to be invited for a specific purpose, so they could answer specific questions. The TCAG Representative questioned the fact that the current Dartford Crossing would remain over-capacity, even with the new LTC, and the over-capacity was one factor that caused incidents. The PBA Representative replied that the modelling showed improved journey times over the Dartford Crossing due to the opening of the LTC, which would potentially increase capacity at both crossings. The Assistant Director LTC added that the traffic model could not model people’s behaviour, so even with an incident modelled at Dartford; it could not model for local people using rat-runs to get to the LTC. She stated that this had to be factored in through mitigation, although this could become complex. She commented that the Council would aim for future mitigation too, which would include future traffic management, as well as environmental mitigation for new technology such as self-driving cars and the increase of electric cars.

The Chair asked if a workshop could be held with HE regarding the proposed rest and service area in Tilbury, as he felt it would be better positioned on the M25 at Brentwood, or at the junction with the A127. The Assistant Director LTC responded that HE liked to put a service area near a tunnel entrance to prevent breakdowns within the tunnel. She added that currently there was an Esso garage at the A2/M20 junction but this would be removed due to the LTC, so the strategic road network would lose one petrol station. She clarified that guidelines suggested one service area every 26 miles. She stated that the Council were currently pressuring HE to close the services at junction 30/31 and build a newer, modern facility before the road split at Dartford Crossing. The Chair agreed with this idea as he felt that a proposed rest and service area at Tilbury would stop traffic and increase environmental concerns.

The TCAG Representative commented that she understood that the Local Plan could not be confirmed until the LTC was agreed, and asked for confirmation that this was the case. She also asked what environmental mitigation HE would have to take into account, as they had stated that as a delivery agency, they would not consider the proposed government ‘climate emergency’. The Assistant Director LTC responded that this was the case regarding the Local Plan, but HE would have to consider the new Net Zero agreement to mitigate environmental factors. She stated she would email Members with more information regarding Net Zero. The TCAG Representative added that the London Mayor had recently pledged to reduce PM2.5, and Michael Gove had suggested a new bill to enshrine World Health Organisation guidelines regarding PM2.5. She asked that if these bills were passed, would this make the LTC scheme untenable. The Strategic Lead – Transportation Development replied that the environmental protection team monitored particulates across the borough, and the Council were currently refreshing the Air Quality Strategy, and would potentially use a new air quality model. He added that although this strategy was only in its infancy, it could affect the LTC and the amount of particulate the scheme would be allowed to produce.

Councillor Spillman stated that a new budget was expected on 6 November 2019, and asked if this would have an impact on the LTC project. The Assistant Director LTC replied that a delay regarding the comprehensive spending review had been expected in the November budget, but nothing had been announced regarding this. She added that an announcement could be made regarding RIS2 spending, but nothing was confirmed. Councillor Spillman also questioned the relationship between the LTC and Local Plan. The Assistant Director LTC answered that the Local Plan could not be confirmed due to uncertainty regarding the LTC, but certainty would only be provided when the scheme was submitted for DCO, which would potentially happen in 2021. She stated that discussions were underway with the MHCLG, and Homes England as the Council were in a difficult position. She added that advice was also being sought from the Planning Inspectorate, but that progress could still be made regarding the Local Plan, including the plan passing through statutory phases.

Supporting documents: