The Blackwall Tunnel is a pair of road tunnels underneath the River Thames in east London, linking the London Borough of Tower Hamlets with the London Borough of Greenwich, and part of the A102 road. The northern portal lies just south of the East India Dock Road (A13) in Blackwall; the southern entrances are just south of the The O₂ (formerly the Millennium Dome) on the Greenwich Peninsula. Before the opening of the Dartford Tunnel in 1963, the Blackwall Tunnel was the easternmost Thames crossing for vehicles, excluding ferries.

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.

The tunnels are not open to pedestrians, cyclists or other non-vehicular traffic. One bus route, the TfL 108 (Stratford-Lewisham) route, runs through the tunnels.

History

The older western tunnel was designed by Sir Alexander Binnie and built by S. Pearson & Sons, between 1892 and 1897. It was originally commissioned by the Metropolitan Board of Works but responsibility passed to the London County Council when the former body was abolished in 1889. The cost of the project was £1.4 million, and seven lives were lost during construction. The tunnel was officially opened by the Prince of Wales on 22 May 1897.

It was then the longest underwater tunnel in the world at 4,410 feet (1,344 m) long. It was constructed using tunnelling shield and compressed air techniques; the shield pioneer James Henry Greathead was a consultant. Sir Joseph Bazalgette, the architect of the London sewerage system, was also involved in the original planning of the project. To clear the site in Greenwich, more than 600 houses had to be demolished, including one reputedly once owned by Sir Walter Raleigh.

Today the western bore is only used for north-bound traffic (and is not accessible to vehicles taller than 4 m). The southern portal features a striking gateway built of red brick. The tunnel itself has several sharp bends. These were built so that horses would not bolt once they saw daylight (motor vehicles were rare in 1897), though the bends may also have been created so that the tunnel avoided the foundations of other structures; another theory suggests the bends avoided tunnelling through a Black Death burial ground. The tunnel carries two lanes of traffic, though higher vehicles need to keep to the left-hand lane so that they do not hit the tunnel's inner lining.

The newer, eastern, tunnel, opened on 2 August 1967, is much wider, usable by vehicles up to 4.72 m and is currently used only for southbound traffic. In 1967 the lighting in the tunnel was commended as "a big improvement" on the standard provided in the "previous" tunnel. In contrast with the Victorian northbound tunnel, the eastern tunnel has no sharp corners — very much designed for 20th century road traffic. Its distinctive ventilation towers (right) were designed in 1961-2 by Terry Farrell when he was working as an architect for the London County Council. The northern pair stand at Blackwall, while the southern are now contained within the Millennium Dome. The towers were Grade II listed in 2000.

Traffic management

The north bound Blackwall Tunnel is a traffic bottleneck with tailback in the morning rush hour as traffic heads north from South East London and Kent towards the London Docklands, City of London, east and Central London. To relieve the congestion, the tidal flow system was introduced in 1978 allowing northbound traffic to use the eastern tunnel. Due to its sharp turns with restricted headroom, high-sided vehicles may only use the left-hand lane of the western tunnel meaning it is not suitable to operate a similar two-way flow in the evening. On 20 April 2007 the tidal flow was discontinued due to reports by Transport for London and the Metropolitan Police of an increase in dangerous motoring behaviour, they cited poor driving, such as overtaking, for the decrease in safety during counterflow operations.

This decision to end the counterflow system was made despite a 2006 independent report, commissioned by TfL, which concluded that "the proportion of accidents occurring in and around tidal flow operations is not significantly higher than would normally be expected on this type of road" and which recommended that "accident mitigation should be focused in the first instance on speed management aspects, and specifically on the deficiencies, limitations, and in some cases, inconsistencies in the signing, signalling and road marking regime". Transport for London made the ending of the tidal flow with immediate effect without advance notice. The ending of the counterflow system has brought protests from users of the tunnel and those experiencing increased congestion due to the change.Former Mayor Ken Livingstone stated that he had "absolutely no plans to set up a congestion charging zone to charge vehicles that use the Blackwall Tunnel or the Blackwall Tunnel Approach Road. But if Greenwich wishes to do so on any of its roads then I will support them".

Unofficial commercial street maps of London periodically show a third Blackwall Tunnel as proposed for construction, though this does not appear in the equally unofficial latest edition of the London A-Z. Although congestion relief plans are regularly discussed, there are at present (2007) no specific plans for a third crossing at the site, although a 'reserved route' in an E-W direction does exist on the Greenwich Peninsula 'Master Plan'.

Maintenance and refurbishment

It is currently proposed to carry out major refurbishment of the Northbound tunnel as the levels of reactive maintenance are now compromising the proper working of the tunnel. An experts group has been convened and is developing a set of options for public consultation.

Work is likely to begin in early 2008 and will take up to 24 months, depending upon which pattern of closures is deemed best by stakeholders, experts and the public.

Nearest alternative crossings

The nearest alternative road crossings are the Rotherhithe Tunnel three miles (5 km) to the west, the Woolwich Ferry two miles (3 km) to the east and the distant Dartford Crossing a total of 12 miles (20 km) farther to the east.

For public transport there is Jubilee Line tube service from North Greenwich tube station (TfL) to Canning Town station on the east and Canary Wharf tube station on the west, and the Docklands Light Railway also passes underneath the Thames between Island Gardens at the southernmost point of the Isle of Dogs, and Cutty Sark in the centre of Greenwich.

Pedestrians and cyclists may also use the foot tunnels at Greenwich (close to the DLR tunnel) and Woolwich (close to the Woolwich Ferry).

References

1. Blackwall Tunnel Tidal Flow Options Study: Traffic & Safety review, Mott MacDonald, April 2006 at

External links

• UK Roads Portal (Links to information about the UK road network)
• The ventilation towers (from the Terry Farrell practice's site)
• Video of the Tunnel (Chris' British Road Directory)
• Petition to keep re-open the tidal flow system