The Silvertown Tunnel: A Century of Connection or a Highway to Gridlock?

For decades, east London’s only river crossing for vehicles between Tower Bridge and the Dartford Crossing has been the Blackwall Tunnel – a pair of Victorian bores that regularly clog during peak hours and cause delays across the A12, A13 and A102. After years of consultation and legal challenges, Transport for London (TfL) is now building the Silvertown Tunnel: a twin-bore road tunnel linking the Greenwich Peninsula with the Royal Docks. The project is the largest single infrastructure investment in the capital’s road network since the M25, with a price tag of roughly £2 billion. But is it a long-overdue fix for a chronic bottleneck, or a multibillion-pound bet that will simply fill up with new traffic?

Why the crossing matters now

The Blackwall Tunnel carries about 100,000 vehicles a day, far exceeding its original design capacity. When it closes – often for incidents, maintenance or high winds – the resulting queues stretch back miles, and rat-running through residential streets in Poplar, Greenwich and Charlton becomes routine. TfL’s business case for the Silvertown Tunnel argues that a second crossing will reduce journey times, improve reliability for buses and freight, and provide a permanent alternative during closures. The tunnel is also designed to accommodate the planned Superloop express bus network, with dedicated bus lanes in the tunnel, which TfL says will make cross-Thames bus journeys faster and more attractive. The project is due to open in 2025, and construction has been underway since 2021.

What the sources show

TfL’s own modelling, published in the 2018 Development Consent Order application, predicted that the Silvertown Tunnel would attract between 38,000 and 44,000 vehicles per day in its first year of operation. That is roughly two-thirds of the number that would be needed to fully relieve the Blackwall Tunnel, because many drivers would still choose the free (but congested) route rather than pay the projected toll. The toll is expected to be in the region of £4 for cars and £7 for heavy goods vehicles, though the final figure has not been set. The GLA Transport Committee, in a 2020 report, noted that the stated benefits of the project were “highly dependent on the level of toll” and that if the toll were set too low, the tunnel could induce significant new traffic, offsetting any congestion relief.

Critics such as the campaign group Stop the Silvertown Tunnel have pointed to the concept of induced demand: the well-documented tendency for new road capacity to generate additional car trips, especially in a region where population and employment are growing. They argue that the tunnel will not solve the underlying problem of too many vehicles competing for limited road space, and that the money would be better spent on rail and river bus improvements. The cross-river bus services are a genuine improvement, but they account for only a small fraction of the tunnel’s projected capacity.

Competing readings of the evidence

The table highlights the fundamental disagreement: TfL sees the tunnel as a piece of a wider transport strategy, while opponents see it as a classic road-building project that will lock in car dependency for decades.

What remains unclear

Three key uncertainties stand out. First, the final toll level. TfL has not committed to a specific price, and the decision will be politically sensitive. If the toll is set too low (say, £2.50) to win public acceptance, the tunnel may induce far more traffic than modelled. If it is set too high, the tunnel may be underused and the financial case collapses. Second, the interaction with the expansion of the Ultra Low Emission Zone (ULEZ) is not fully modelled. The ULEZ, which now covers the whole of Greater London, charges older, more polluting vehicles. It may reduce the number of older diesel vehicles using the tunnel, but it does not cap the total number of vehicles. Third, the long-term impact on the Thames freight route is unclear: the tunnel will connect to the A102 and A13, which are already congested, and there is no coordinated plan to manage demand on the approaches.

Practical checks for readers

If you live or commute in east London, the Silvertown Tunnel is likely to affect you, whether you drive, use the bus, or cycle. The opening date is currently projected for 2025, but infrastructure projects often slip. You can follow TfL’s project updates on the official page and check the GLA Transport Committee’s recommendations for ongoing scrutiny. For those who want to track the air quality argument, the London Air Quality Network publishes real-time data for monitoring stations in Greenwich and Newham. The final toll decision will be made by the Mayor of London and TfL, and it will be worth watching for public consultations in 2024–2025. Until then, the evidence remains balanced between a genuine capacity fix and a textbook case of induced demand.