The construction of London’s Underground network has been a varied mixture of schemes and methods that have been taking place on and off since the 1860s, ranging from the early cut-and-over methods through to the later shield machine deep tunnelling that created the distinct cylindrical tunnel shapes that led to the ‘Tube’ nickname.
As with any tunnelling project, however, the means of excavating soil and rock are no more important than the means of extracting the excavated debris. This is why any tunnel worker knows that progress depends as much on having an effective conveyor belt installed behind them as it does on having a powerful machine boring away in front of them.
Recent years have seen this process continuing in various places across the capital, most notably in the Northern line extension to Nine Elms and Battersea Power Station, as well as the Crossrail Elizabeth line (officially not part of the London Underground, although it has long underground sections, rather like Merseyrail in central Liverpool).
Boring A Bigger Bakerloo
The next scheme will be to extend the Bakerloo line beyond its current southern terminus at Elephant & Castle. This project has taken a significant step forward with the appointment by Transport for London (TfL) of the consultants for the feasibility study for an extension as far as Lewisham, with four new stations.
AECOM and WW+P will carry out and deliver the study over the next eight months on plans that would see the line extend along the line of the Old Kent Road and beyond, with planned stations at Burgess Park, Old Kent Road, New Cross Gate and finally at Lewisham.
The third of these will connect with the Overground at what used to be one of the two southernmost stops on the Tube’s East London line (which means the Overground actually has an underground section comprising five stations between Canada Water and Aldgate East), plus the Docklands Light Railway at Lewisham.
Regional director for Europe at WW+P Steve Bell said: “We’re pleased that our work could see the progression of one of the most significant next programmes of regeneration in the region centred around transport-oriented development.”
The importance of the development would be obvious, with the line being unusual in terminating in Zone 1, where it has stopped since it opened in 1906. TfL estimates that the cost will be between £5 billion and £8 billion, with the extension potentially operational by 2040.
Political Support For The Line
Among the keenest advocates of the extension is Lewisham mayor Brenda Dacres, who recently told a conference in the City of London that the extension will “unlock over 107,000 new homes and 150,000 new jobs”. Local MPs and other politicians representing the area have also been pushing the case.
South London is now the most obvious place for further tunnelling, with most of the Underground, including large stretches of surface line, being situated north of the Thames. Indeed, TfL is also considering the possibility of taking the Bakerloo line further beyond Lewisham, perhaps by adapting existing surface rail lines between Catford and Hayes. However, in the meantime, the focus will be on a section that will need to be tunnelled.
Some of the challenges will be less technical than those faced when tunnelling north of the river, where the presence of several other subterranean tunnels, including but not limited to the Tube, means in some places the excavation work has to be very precise to avoid encroaching on existing tunnels.
HS2 Tunnels To Be Confirmed?
The most significant piece of tunnelling work from a transport perspective north of the river in the near future is expected to be the excavation of tunnels to take HS2 from Old Oak Common to Euston, which will also have a major impact on the redevelopment of the much-criticised station.
After the government said it would review plans to take the line into central London, transport secretary Louise Haigh said this month that the extension is likely to take place.
She told Times Radio: “We’ll be making an announcement on that soon … it certainly doesn’t make – it would never have made sense – to leave it between Old Oak Common and Birmingham.”
HS2 has already seen considerable tunnelling in west London and elsewhere, with 65 miles of tunnel set to be excavated between London and the West Midlands.
Excavating all the material is a huge undertaking, with 130 million tonnes of rock and soil being extracted, enough, HS2 has stated, to fill Wembley Stadium 15 times over. Suffice to say, that will have proved a lot of work for the conveyor belts ferrying back to the surface.
