The Blackwall Tunnel is a pair of road tunnels running beneath the River Thames in East London, England. It connects the London Borough of Tower Hamlets on the north bank with the Royal Borough of Greenwich on the south, forming part of the A102 road. The northern entrance lies just south of East India Dock Road (A13) in Blackwall, while the southern portals are located near The O2 Arena on the Greenwich Peninsula. The crossing is owned and maintained by Transport for London (TfL).
History and Development
The first bore of the Blackwall Tunnel was opened in 1897 by the then Prince of Wales (later King Edward VII). At the time, it was a groundbreaking infrastructure project, designed to boost trade and connectivity in London’s East End, an area that had seen rapid industrial and commercial growth. The tunnel carried a mixture of pedestrians, cyclists, horse-drawn vehicles, and early motor traffic, and was considered an engineering marvel of its day.
However, by the early 20th century, traffic levels had already begun to outgrow the tunnel’s capacity. By the 1930s, congestion had become a serious problem. To address this, a second bore was constructed and opened in 1967, dedicated to southbound traffic, while the original Victorian tunnel was converted to carry northbound traffic.
Strategic Importance
The tunnel’s approaches connect two major arterial routes: the A12 in the north and the A2 in the south. This makes the Blackwall Tunnel a critical link not just for local journeys across the Thames, but also for longer-distance traffic traveling between Kent, South East London, and Central London. Before the Dartford Tunnel opened in 1963, the Blackwall Tunnel served as the easternmost all-day vehicular crossing of the Thames.
Due to its location and function, the tunnel has long been prone to heavy congestion. To manage traffic flow, a tidal flow system was introduced in 1978, allowing the direction of one tunnel to be temporarily reversed during peak hours. However, this system was removed in 2007 amid safety concerns, sparking controversy among regular users.
Modern Era and the Silvertown Tunnel
For decades, the Blackwall Tunnel remained the only free fixed road crossing of the Thames east of Tower Bridge, until the opening of the Silvertown Tunnel on 7 April 2025. The new tunnel was built to ease the immense pressure on Blackwall, which was often gridlocked and hampered by the 4.0-metre (13.1 ft) height restriction of its Victorian bore.
With the opening of Silvertown, both tunnels became tolled crossings, marking a major shift in how Londoners and commuters access the Thames in this area. The pair now function as a coordinated system, helping to balance demand and reduce bottlenecks that have historically plagued the route.
Usage and Restrictions
Unlike in its early days, the Blackwall Tunnel is no longer open to pedestrians, cyclists, or other non-motorised traffic for safety reasons. Instead, it remains strictly a road tunnel, accommodating thousands of vehicles daily. One notable service using the route is London Buses route 108, which runs between Lewisham and Stratford—one of the few bus routes in the capital that crosses under the Thames.