Transport for London (TfL) are developing proposals for a new road tunnel linking the Greenwich Peninsula and Silvertown, with the aim of reducing delays and closures at the historic Blackwall Tunnels by improving connections and offering alternative river crossing options.
The Silvertown Tunnel would be the first highway River Thames crossing since opening of Dartford Tunnel in 1980. Currently in East London, the River Thames can be crossed by Rotherhithe, Blackwall & Dartford tunnels, Queen Elizabeth II bridge and the Woolwich Ferry. The Silvertown Tunnel, which could become operational in 2021 at earliest, would add significant capacity to the existing infrastructure. The plans have come up against fierce opposition from some who argue the tunnel is likely to draw additional traffic to an area where pollution levels are already unsafe.
TfL’s case for new tunnels is pinned on what they identify as three key positive impacts: that a bigger crossing will reduce congestion and therefore pollution at the Blackwall tunnel; that it will improve the reliability of the crossing and avoid regular closures due to overweight vehicles attempting to enter the Blackwall tunnel; and that improved infrastructure will support the development of surrounding areas. TfL plan to implement a charge at the Silvertown and Blackwall Tunnels, in order to manage demand and to help pay for construction and operation of the new tunnels.
TfL explain that over a 9 month period, the Blackwall Tunnel had to be closed over 1600 times, the majority of which (70 per cent) were due to drivers ignoring the height restriction warning signs throughout the Northbound tunnel, which has a 4 m (13 ft) height limit. Regular strikes from over-height vehicles cause regular closures for short periods of time but cause congestion to build up quickly. TfL argue that the resilience of the crossing (i.e. the provision of alternative routes during closures) will be improved with introduction of the Silvertown Tunnel.
The proposed Tunnel generally follows the alignment of the Emirates Air Line cable car. Twin bore tunnels, both about 1 km in length, would pass under the River Thames, inside an area of land that has been safeguarded for this purpose. The tunnel would connect to the A1020 Silvertown Way/Lower Lea Crossing on the north side and to the A102 Blackwall Tunnel Approach on the south side. Unlike the Blackwall Tunnel, which would likely be used by longer-distance traffic, the Silvertown Tunnel would carry more local traffic as well as vehicles which are too tall to use the Blackwall Tunnel. Pedestrians and cyclists would not be able to use the Silvertown Tunnel.
The official statutory consultation is planned for summer 2015. TfL aim to finalise plans for the new tunnel and an application for Development Consent by the end of 2015. On this timescale, a decision on application could be made by mid-2017 and construction complete in mid-2021 at earliest.
Campaign groups including “No to Sivertown Tunnel” oppose the plans, raising concerns that increase road capacity may lead to more traffic and could in fact add to pollution levels. Critics add that regeneration would be better served by investing in public transport, and that the resilience of the crossing could be better addressed by using technology to intercepting trucks before they approach the tunnels.
Design of the Silvertown Tunnel on Greenwich Peninsula
Design and engineering group Atkins, who were commissioned to create the reference design for the proposals, describe the tunnels as two 11.45 m internal diameter bores, each of approximately 1.0 km in length, with two traffic lanes per bore and connecting cross-passages. Cut-and-cover approaches would be created at Greenwich and Silvertown, each of approximately 0.2km in length. The approaches would carry the same number of the traffic lanes as the bored tunnel and would comprise emergency cross-passages. Each approach will include a Tunnel Boring Machine chamber at the interface with the bored tunnel in order to facilitate its construction.
On the south side (Greenwich Peninsula), northbound traffic would enter the Silvertown Tunnel along a new spur branching off from the existing Blackwall Tunnel Approach road. Southbound traffic leaving the tunnel on the south side would join the existing Blackwall Tunnel Approach southbound. To achieve this, TfL propose a number of changes to existing road network on the south side, on the immediate approach to the new tunnel:
- Widening of A102 Blackwall Tunnel Approach in order to create new access routes to the Silvertown Tunnel.
- Demolishing and replacement of existing footbridge near the junction with Boord Street.
- Building a new flyover to take southbound traffic existing the Blackwall Tunnel over the northbound approach to the Silvertown tunnel.
- Introducing new signage to direct motorists either to the Blackwall Tunnel or Silvertown Tunnel, depending on their destination.
- Creating a new tunnel services building over the mouth of the new Silvertown Tunnel to house ventilation equipment and other infrastructure.
Detailed plans (below) show the creation of a bus-only lane carrying traffic from Millennium Way and into the northbound traffic Silvertown Tunnel. The bus-only route could more effectively route traffic from the which North Greenwich Interchange (Underground and bus station) towards Silvertown.
The land on which redevelopment of the Tunnel junction is to take place on the Peninsula, highlighted yellow below, straddles the border of the 2004/2015 Greenwich Peninsula Masterplan area (red outline). The proposed location of the tunnel's service buildings - north of the gas cylinder - lies just outwith the Masterplan area, as does the Boord Street footbridge which is to be demolished and replaced.
Knight Dragon's proposed 2015 Masterplan states that the development site for the tunnels is safeguarded and constraints are placed on development over and adjacent them. As a result, some phasing of the Masterplan is linked to changes in movement infrastructure.
The expected commencement of the Silvertown Tunnel works circa 2019 is likely to disrupt key movement routes such as Millennium Way and require significant areas of land for an operations compound while under construction. This land is currently being used as surface parking for The O2. The O2’s parking is critical to its operation, and it is intended that the eventual rehousing of the parking will be to the multistory AEG carpark proposed in the 2015 Masterplan.