The challenge to make London's Victorian Tube network accessible

Mayor Boris Johnson has announced a £75m fund to install lifts at "around a dozen" London Underground stations over the next 10 years. But how do you update a Victorian underground railway system?

It was in 1863 that London began its ambitious new phase of underground development. Built by the Metropolitan Railway, the original track stretched just three miles between Paddington (then Bishop's Road) and Farringdon - part of what is now the Metropolitan line. Since then, the London Underground has become one of the main modes of transport in the city - but one which remains inaccessible in large part to those with limited mobility.

Despite initial concerns from objectors that the tunnels would collapse under the weight of the traffic overhead, a piecemeal development process over the next 150 years saw the Tube develop into a vast network that today sees almost four million passengers a day travelling across 270 stations.

At certain points the railway is 58.5 metres below the surface and so a challenge for many to reach and a challenge to make accessible.

"Fire regulations prohibited wheelchair users on the Underground before 1993 so it's a matter of playing catch-up," says Christian Wolmar, author of Down the Tube: The Battle for London's Underground.

Engineers now have the problem of "retrofitting" lifts around old infrastructure below very congested city streets.

"There is no easy way to modify stations," says Allan Thomson, Sponsor for Station and Interchange Development at Transport for London (TfL). "Take Green Park for example. We decided to make that station step-free due to its location and how it could be used during the Paralympic Games 2012 but firstly we had the logistical problem of finding a work site close to the station to put all the equipment involved."

There were already lifts at low level for connection to the Jubilee and Piccadilly lines. Thompson explains they needed to create two new lifts connecting the Victoria line to both the street and the ticket hall.

"We had to lower a single shaft through the infrastructure already in place," he says. "It was like finding a needle in a haystack going down in between the existing structures and wiring. We had to ensure that the lifts all properly connected as well as the power, lighting, CCTV, and all the while ensuring that the station remain in service. Closing the Victoria line would have made the job a lot easier but it's just not feasible."

Faryal Velmi, director of Transport for All, an organisation that campaigns for better access on the underground, says she understands it is difficult for TfL to close stations but that she is often left frustrated by their decisions.

"We think access to transport is a civil right," she says. "Of course it's difficult for TfL to close stations to do the work they need to do, but the Tube is the easiest and quickest way to get around London and it's unfair that disabled people can't use most of it."

At present TfL provides trained staff to help people in need of assistance with their journey but Velmi is concerned that with the announcement of staff cuts this might be harder to maintain as a service and so would be a step backwards. She is also concerned that accessibility for all disabled people, not just wheelchair users, is factored into plans.

The Green Park project took two years to complete and cost £50m. Funding for this particular project came from TfL as part of an investment programme to make transport in London more accessible ahead of the Paralympic Games in 2012.

Thomson says the projects will always be expensive but they try to reduce costs by piggybacking on other work being carried out. "At Finsbury Park, for example, Network Rail are going to install lifts to their platforms so we are going to put a lift in while they are completing their works." He says they expect this to also cost £50m.

For campaigners like Velmi, the cost argument is tired. She says: "We feel that there should be a pot of money ring-fenced by the government to ensure that this work is done."

There are often very important reasons to make tube trips, she says: "There is a narrative from the government that disabled people should be encouraged to find work but what if a disabled person is unable to access an underground station close to where they live or work?"

Featured in a video highlighting access issues on the service, wheelchair-user Anthony Ince says he feels momentum has slowed since 2012. He says it can be exhausting trying to establish which stations are step-free: "It's too difficult to know where I can and can't get to when I take the tube. It feels like us wheelchair users are being ignored despite how positively London came across during the Paralympics."

But will there come a time when every station on the London Underground is accessible? And do they even need to be?

For Thomson it is about prioritising investment where it will get the most benefit: "Investing in making absolutely all underground stations accessible would need to be weighed up against the benefits of investing in other transport and access improvements." For example, he says that new, fully accessible lines such as those proposed for Crossrail 2 or the Bakerloo line extension could benefit more people over a wider area.

And with Boris Johnson's announcement on Wednesday that funding has been secured for five more Crossrail stations, campaigners say they feel progress is being made.

"We were livid when we heard initially that there would be stations on the Crossrail that wouldn't be accessible in the 21st Century," Velmi says. "We have been lobbying hard and are so delighted that disabled people will be able to participate in London life more easily."

TfL have scheduled a lot of work to increase accessibility across the London Underground in the next 10 years, and they are also investing in the bus network as well as ensuring that overground networks remain fully accessible. But with funding still not secured for three Crossrail stations and an opening date of 2019 it seems that accessibility is still not guaranteed.

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