The tunnel is working, the pavement is not: Silvertown at 18 months
The Silvertown Tunnel opened in April 2025 with a promise that it would ease the chronic bottleneck at Blackwall and speed up cross-river journeys. Eighteen months later, the evidence is more nuanced than either its supporters or its critics tend to allow. Traffic has shifted. Bus journeys have improved on some corridors. Air quality has changed, but not uniformly. The tunnel is doing part of what it was designed to do. The question now is whether the public bodies that promoted it are willing to fund the less glamorous work that would make it a genuine transport improvement rather than a redistribution of congestion.
TfL's monitoring reports, borough traffic counts and the published minutes of the Silvertown Tunnel implementation group provide the best available picture. They do not support the simplest claims. The tunnel has not eliminated traffic from Blackwall. It has not produced a dramatic fall in air pollution across the whole of Greenwich Peninsula. It has not made every bus journey faster. But it has changed the geography of delay, and that matters.
What the counts show
The clearest effect is on the approach to the Blackwall Tunnel. Northbound queues on the A102, which once stretched back through Greenwich Peninsula at peak times, have shortened on many weekdays. TfL's 12-month monitoring report recorded a reduction in average peak journey times for southbound traffic using the Blackwall crossing, although the improvement varies by time of day and direction. The Silvertown crossing itself has absorbed a significant share of vehicles that would otherwise have used Blackwall. That is not surprising: the new tunnel was designed to provide additional capacity, and it has.
The less comfortable finding is that overall traffic across the river has not fallen. In some periods it has risen. This is the familiar phenomenon of induced demand: additional road capacity encourages journeys that were previously suppressed or made by other routes. TfL's data suggests that some of the new crossings are not replacing Blackwall journeys but adding to the total. That does not make the tunnel a failure. It does mean that the congestion relief is local and partial, not system-wide.
Bus reliability is a mixed picture. Cross-river routes that use the new tunnel have benefited from more predictable journey times, particularly outside the peaks. But reliability on the approaches to the tunnel, and on the Greenwich Peninsula road network, remains fragile. A bus that saves four minutes in the tunnel can lose them again at a badly timed junction or a bus stop blocked by parked cars. TfL's own performance data shows that the variance between the best and worst journeys on some cross-river routes is still wide.
Air quality is the most contested measure. Monitoring stations around Blackwall Reach have recorded lower concentrations of nitrogen dioxide in some periods, consistent with reduced queuing on the approach. But the picture on Greenwich Peninsula is less clear. Traffic has been redistributed rather than removed, and background pollution from other sources remains significant. Anyone who claims the tunnel has solved air quality in the area is overstating the evidence. Anyone who claims it has made no difference is ignoring the monitoring.
The fixes nobody wants to fund
The real test of the Silvertown scheme was never the tunnel bore. It was whether the new crossing would be accompanied by improvements that make walking, cycling and bus travel more attractive than driving. On that measure, the record is thinner.
Blackwall Reach and Greenwich Peninsula are precisely the places where complementary investment would matter most. The tunnel lands in a landscape of dual carriageways, retail parks, construction sites and bus stops that are often poorly connected to the communities they serve. A new crossing can move cars more efficiently without making it easier for a resident of east Greenwich to reach a bus stop, a GP surgery or the Thames Path. The missing pound is not in the tunnel; it is in the pavement, the crossing, the bus lane and the wayfinding.
TfL and the boroughs have identified a list of possible improvements. Bus priority measures on the approaches to the tunnel would help reliability. Better walking and cycling links between Blackwall Reach, East India Dock and the Greenwich Peninsula would reduce short car trips. Improved interchange at North Greenwich would make cross-river bus journeys more coherent. None of these schemes is technologically difficult. The obstacle is funding and ownership: TfL has a capital programme under severe pressure, Greenwich and Tower Hamlets have their own budget gaps, and no single body wants to pick up the revenue cost of running additional bus services.
That is the awkward politics of the Silvertown Tunnel at 18 months. The tunnel is a mayoral project with a clear ribbon-cutting moment. The complementary measures are unglamorous, dispersed across borough boundaries and expensive to run. They are also the measures most likely to determine whether the scheme reduces car dependence or simply moves congestion around.
What City Hall should do next
The mayor and TfL should publish a clear, ring-fenced plan for the complementary measures, with dates and funding sources. That plan should include bus priority on the approaches to Silvertown and Blackwall, a walking and cycling audit of Blackwall Reach and Greenwich Peninsula, and a commitment to monitor not just traffic volumes but bus reliability and air quality at a finer geographic scale. The boroughs should be brought into that plan early, rather than asked to co-fund schemes after the political capital has been spent.
None of this is a reason to regret the tunnel. It has provided additional cross-river capacity and improved some journeys. But the first 18 months show that infrastructure alone does not change travel behaviour. The tunnel is working as a road. The pavement is not working as a network. Until City Hall funds the missing links, the Silvertown scheme will remain a partial success: better than the status quo, but short of what was promised.
