TFL to discuss Silvertown Tunnel at next open meeting
May 12, 2015
TfL are attending our open meeting on 19th May to update us on their proposals for the Silvertown Tunnel and to answer our questions. They will be represented by Matt Yates, TfL’s Head of Planning Projects and he will interact with us for the first 30 minutes of our meeting.
We asked TfL 9 basic questions at a previous small meeting. They have given answers to 7 of them and we hope they can expand at the open meeting.
Come and discover what doubling the tunnels may mean to you.
Our Q's and TfL's A's below:
1. Peak time capacity of the Blackwall Tunnels?
Based on the current operation of the Blackwall Tunnel and with the aid of traffic count data collected over the last few years, the peak capacity of the Blackwall Tunnel is approximately 3,200 passenger car units (pcus) in the peak hour in the northbound direction, and 3,900 pcus in the peak hour in the southbound direction. You may know that Blackwall is ‘tidal’ in nature – the northbound bore is busiest in the morning peak and the southbound bore is busiest in the evening peak.
The southbound bore has a greater capacity than northbound because it was constructed much more recently (opened in 1967, northbound was opened in 1897) and so the design was better optimised for motorised traffic from the outset.
2. Combined peak time capacity of all tunnels?
The Silvertown Tunnel will provide a general traffic lane (i.e. usable by all vehicles) and one reserved bus/HGV lane in each direction, in addition to the capacity at Blackwall as outlined above. The capacity of each general traffic lane will be around 1,700 pcus. We’d like to stress however that the introduction of this additional capacity will be accompanied by user charging, where the objective is to manage demand in order to ensure that the main benefit of the additional capacity is a reduction in delays and peak journey times. Consequently, whilst the peak-time flows on the Silvertown and Blackwall Tunnels combined are expected to be higher than current Blackwall-only levels, this increase will be less than the increase in available capacity.
3. Current peak time flow; what is predicted flow in 2021 – 2026?
a. Without/With Silvertown Tunnel?
b. Without/With Tolls?
We published charts during the consultation to show the use made of the Blackwall Tunnel now and in each direction over a 24 hour period throughout the week. These charts are on page 5 of the factsheet ‘Why build the Silvertown Tunnel?’ which is attached.
In regards future traffic levels, our traffic modelling forecasts traffic levels in a 2021 ‘Reference case’, based on the effect that population and economic growth, as well as committed transport schemes, might have on traffic levels by this time. We will have not modelled traffic levels in 2026. The table below was taken from our Traffic Forecasting report, which is available from our website, and shows the changes in trips by car and van (we’ve listed these as simply ‘Car’ for ease of reference in the table) and public transport modes. Background growth in London’s population, and an improving economy in London, will increase all types of trip, including trips by car or van.
We consider the Silvertown Tunnel and user charge to be parts of the same overall scheme, so have not modelled the effect of the Silvertown Tunnel itself in isolation, or user charging in isolation. It is expected that shortly after the Silvertown Tunnel opens in 2021/22, the northbound peak hour demand for both tunnels could be around 4,000 pcus whilst the southbound peak hour demand (PM peak) will be close to 5,000 pcus. However, this is highly dependent on the charging levels that will ultimately be implemented – this is currently the subject of ongoing analytical work.
4. What was peak time flow during the “tidal flow” era?
We are compiling historical data to show peak times through Blackwall Tunnel when tidal flow was in operation – I will send this information through separately as soon as it arrives. I should say that the tidal flow system was operated by the Metropolitan Police, who withdrew it on the basis of safety concerns.
5. Origin/Destination of traffic through the Blackwall Tunnel and whether this is this likely to change?
I’ve attached a PDF document to show the origin and destination of trips through the Blackwall Tunnel. We are undertaking further work to determine to what extent the origin of trips changes in 2021 both with and without the Silvertown Tunnel/user charge. Once this work is complete I’ll write again. [The expanded Origin/Destination map is shown below]:
6. The apparent lack of current regulation and ability to tackle height related incidents, there have been 600 to date in the Northbound tunnel?
I’ve copied below a chart to show the number of incidents in which an overheight vehicle attempts to access the northbound bore of the Blackwall Tunnel. The number of incidents has reduced over time as our systems for preventing such incidents have improved. These systems include the introduction of a designated Roads Response Team, who are based on-site to deal with issues and incidents, and the implementation of an over-height detection system.
An extensive refurbishment of the northbound tunnel bore was also completed in 2011 to ensure it is serviceable for many years to come. These improvements have considerably improved journey time reliability and reduced the number and resolution time of incidents occurring, with the number of over-height vehicle incidents in particular being significantly lower than prior to the implementation of these improvements.
Other, more radical interventions to increase resilience at Blackwall Tunnel (such as re-engineering the northbound bore to accommodate larger vehicles) would not provide the same benefits in journey time or capacity terms as the Silvertown Tunnel. Re-engineering the northbound bore to accommodate larger vehicles would have an extremely high cost and result in significant disruption during implementation.
As well as providing a significant enhancement in crossing capacity, the Silvertown Tunnel will provide much greater network resilience which will benefit users of both Blackwall and Silvertown tunnels. It will provide an opportunity for reducing the occurrence of incidents in the Blackwall Tunnel (partly by being able to accommodate vehicles of a greater height in the northbound direction), to mitigate the impacts of those incidents that do occur, and to offer a diversionary route to traffic affected by these incidents.
As part of the overall scheme it is proposed that a comprehensive signage strategy will be implemented to ensure that as much potentially ‘overheight’ traffic as possible is directed to use the Silvertown Tunnel, and this will further reduce the number of over-height vehicle incidents at Blackwall Tunnel. In the event of an incident at Blackwall Tunnel, where safe to do so traffic will be directed to use the Silvertown Tunnel as an alternative. Traffic will no longer be required to make lengthy diversions to other road crossings, and this will significantly reduce the impact that any closure of Blackwall Tunnel will have on the road network.
7 & 8. Plans for “improving” feeder roads to all tunnels by 2021? And, plans for improving public ‘cross river’ transport from East Greenwich (and beyond)?
Our next consultation on the Silvertown Tunnel – planned for autumn 2015 – will include further details on what new bus links we could introduce through the Silvertown Tunnel, as well as any schemes on the wider road network that we judge necessary.
9. A simple illustration of the relationship between vehicle speed and pollution emissions?
We are tracking down a relevant document and I will forward this asap.
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