The Blackwall Tunnel is a pair of road tunnels underneath The River Thames in east London, England linking the London Borough of Tower Hamlets with the Royal Borough of Greenwich, and part of the A102 Road. The northern portal lies just south of the East India Dock Road (A13) in Blackwall;A the southern entrances are just south of The O2 on the Greenwich Peninsula.B The road is managed by Transport for London (TfL).
The tunnel was originally opened as a single bore in 1897 by the then Prince of Wales, as a major transport project to improve commerce and trade in London's East End, and supported a mix of foot, cycle, horse-drawn and vehicular traffic. By the 1930s, capacity was becoming inadequate, and consequently a second bore opened in 1967, handling southbound traffic while the earlier 19th century tunnel handled northbound.
The northern approach takes traffic from the A12 and the southern approach takes traffic from the A2, making the tunnel crossing a key link for both local and longer-distance traffic between the north and south sides of the river. It forms part of a key route into Central London from South East London and Kent and was the easternmost all-day crossing for vehicles before the opening of the Dartford Tunnel in 1963. It remains the easternmost free fixed road crossing of the Thames, and regularly suffers congestion, to the extent that tidal flow schemes were in place from 1978 until controversially removed in 2007.
Proposals to solve the traffic problems have included building a third bore, constructing alternative crossings of the Thames such as the now cancelled Thames Gateway Bridge or the Silvertown Link, and providing better traffic management, particularly for heavy goods vehicles. The tunnels are no longer open to pedestrians, cyclists or other non-motorised traffic, and the northbound tunnel has a 4.0-metre (13.1 ft) height limit. One bus route runs through the tunnels.