As a flurry of commuters navigate their way around a station closure, temporary bus stops, and alternative routes out of E17, under the streets of Walthamstow, it is all systems go.

Since the Central Station closed on August 8, at every minute, there has been a 100-strong team of engineers, managers and Underground staff teaming up to carry out an £11m transformation of part of the Victoria Line.

Down in the dark tunnels men have been digging, welding, and working to replace the old diamond crossover.

Though the station may look the same when they complete on Monday, residents of Walthamstow will feel big change in the efficiency of the service, according to John Hardy, the head of track programme for London Underground.

“We only do two blockades a year, which are extended closures of the line. This is the biggest one for around ten years, since the Brixton crossover.

““The crossover is the means by which we can take a train and turn it round to send it back again.

“The old crossover is the one that was put in originally when the Victoria Line was built. It was wood cast in concrete, and the wood rots and shrinks over time.

“So maintenance costs are high.

“The trains have to cross it at a relatively low speed. If we didn’t replace it we would have to make the trains even slower when they pass.”

If all goes to plan, when the line re-opens it will go from end to end, without having to turn around every other service at Seven Sisters.

Also, the train will not have to slow to come into Walthamstow.

Because of this, the train frequency will go up to 34 per hour when the station re-opens next week, and will be 36 per hour after signalling works are completed elsewhere.

This will make it one of the most high frequency lines in the UK.

“The project manager has been working on this for two years.

“People who use the line will feel a difference, for a start it should ease overcrowding.”

Last Saturday, August 22, a whopping 300 cubic metres of concrete was laid around the new crossover.

It was brought to the station car park in 54 lorries and pumped through a pipe into the underground.

“We would not close a station unless it was absolutely necessary.

“We have been working around the clock to make sure it runs on time. We have planners in the office going over every detail, against a timeline. So far, I see no reason why we shouldn’t hand back at the arranged time on Bank Holiday Monday.”

The work is being carried out by Track Partnership, an organisation formed by Balfour Beatty and London Underground.

At the moment, the new crossover is in, the concrete has been laid and the last jobs are being completed.

Ticket offices will be shut when the station re-opens and there will be only one escalator in use at all times.