Blackwall Tunnel

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The Blackwall Tunnel is the name given to a pair of road tunnels underneath the River Thames in east London, linking the London Borough of Greenwich with the London Borough of Tower Hamlets. The southern entrances are just west of the Millennium Dome on the Greenwich Peninsula; the northern portal lies just south of the A13 in Blackwall.

The tunnel crossing is a key link between north and south sides of the river and forms part of a key route into central London from south-east London and Kent. The southern approach takes traffic from the A2 trunk route (for some years, the section north of the A2 Rochester Way Relief Road was regarded as a motorway (the A102M); however, this reverted back to being the A102 in September 1999 when the opening of the A12 north of the tunnel prompted a rationalisation of the area's road numbering systems).

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History

Image:Blackwall tunnel towers 1.jpg

The western tunnel was built at the end of the 19th century, while the other was added some 70 years later.

The older western tunnel, designed by Sir Alexander Binnie and built by S Pearson & Sons for London County Council (although originally commissioned by the Metropolitan Board of Works) at a cost of £1.4 million, was 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 took six years to construct, using tunnelling shield and compressed air techniques (shield pioneer James Henry Greathead was a consultant; Sir Joseph Bazalgette was also involved in the original planning of the project), and seven people died in the process. 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. Some suggest these were built so that horses would not bolt once they saw the 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. 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 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.

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Traffic management

The Blackwall Tunnel is a notorious traffic bottleneck. Long tailbacks form in the morning rush hour on weekdays as traffic heads north from SE London and Kent towards central London. The transport authorities therefore try to increase flows by opening one lane of the eastern tunnel to northbound traffic for two hours; this, of course, means there is only one lane for southbound traffic so the northern approaches quickly become jammed each morning. Unfortunately, the western tunnel is not suitable to operate a similar two-way flow in the evening, so the northern approaches are frequently even more congested in the late afternoon and early evening.

The nearest alternative crossings are the Rotherhithe Tunnel three miles (5 km) to the west or the Woolwich Ferry two miles (3 km) to the east.

The tunnels do not allow pedestrians, but a bus route (number 108) operates through the tunnel. When the service is not running, the nearest pedestrian crossings of the river are the Woolwich foot tunnel adjacent to the Woolwich Ferry (see above) and the Greenwich foot tunnel about two miles (3 km) to the west. However, 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.

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