Rats. Diseases. Pitch dark. 130° heat. Airless, confined spaces. No water. Entombed under 30 m of concrete. Endless tunnels. All night, every night. This is not a recurring nightmare, it's a job. We took a journey to the end of the night with the track replacement boys.
It wasn't meant to be like this. When Danny Francis left school in Plaistow towards the end of the 1980s he planned to go to college to do a computer course. At the time, everyone agreed that IT was the profession of the future: get in on the ground floor you'd have more work than you wanted, and as much money as you needed.

Then his girlfriend became pregnant, so he needed a job in a hurry. Unfortunately, it was 1991 – not the best year to be looking. Luckily, his dad worked for London Underground. He put in a good word, and Danny ended up on a track maintenance team. He's been there ever since, officially as a track worker, but in the past two-and-a-half years he's been based in the office.

That's an important gain. He took an engineering course in the hope of consolidating it but he's failed the first exams and now there's a possibility that his employers at Metronet are going to send him back to the tracks. Danny hates the tracks: he hates the night shifts, the boredom, the exhaustion.

To understand what life is like for a track worker, Building took a night tour of the underground system with Danny, starting at Metronet's South Kensington depot, where the workers are waiting for their 11.30pm briefing.

The first thing you notice about the job is the relentless grimness of your surroundings. The depot has the air of a prison visiting room: it is heated to prison temperature, the walls are painted that shade of pale custodial green traditionally favoured by HM Prison Service. There's no food, but there are a few kettles and microwaves if you've brought your own.

Boredom is a constant. Management insist that the men turn up at 11, but there's nothing much to do apart from make phone calls and play cards until the time comes to split up into eight-strong teams for a briefing in one of the windowless cubicles off the canteen.

In the briefing, it quickly becomes clear that the teams are divided between old sweats and new guys. The sweats transferred from LU after the Metronet consortium took over, and brought with them their statutorily protected terms and conditions and free travel passes for them and their families. This isn't part of the deal for guys hired by Metronet, and the difference rankles.

Management consultants have been called in, and they want changes to the way the work is done. The attitude of the new men is yeah, whatever, but the old lags men regard this as at best a waste of time, at worst, heresy.

Bob Searle, Metronet's principal night manager, tries to jolly them along. "There's no going back," he says. Continuous improvement is Metronet's philosophy. "If it doesn't work tell them, but you've got to give their ideas a try." E E At 12pm the teams set off for their rendez-vous with the Underground. Danny drives us to Tottenham Court Road station. It's Monday night, one of the slack periods in the capital's hectic schedule, and Westminster council men are heaving bags of McDonald's waste into snorting dustcarts.

Tottenham Court Road
The station has just closed. It's due to reopen at 5.25am, which means that the maintenance crews need to be out by 4.30am to make way for the cleaners. Lee Turner, the assistant station manager, says that the track workers are supposed to clean up after themselves – it's in the contract. But the station supervisors prefer them to be out earlier and get their own cleaners in to do the job properly.

That leaves about four hours to actually do something. Or rather, it leaves two and a half: the team's job is to grind the concrete blocks under the sleepers prior to replacing them, and it takes an hour to set up the kit, and another half to pack it up again.

The kit, and the rest of the team, are supposed to be delivered by an engineering train that runs off batteries. The men sit on the floor and wait for it to turn up. And wait. And wait. It's a play by Samuel Beckett. None of them have brought anything to do or read or drink and so they sit on the platform floor in silence. Nobody knows what's happening. After an hour, a cleaner comes in and starts scraping chewing gum off the floor with a chisel.

Why haven't they brought anything to drink? In summer, the temperature can hit 130°F in the tunnels; workers can sweat a sizeable proportion of their body weight. Well, safety rules say they can't bring their own bottles onto site. LU used to provide large ones, but this was stopped after privatisation because water was being wasted. They've since been issued with regulation water bottles, but they all leak. The Tube's communications are notoriously primitive. Mobiles don't work, wall phones are available only on platforms, walkie-talkies are used only by certain people, such as fire marshals.

At 1.39am, one of the guys uses the fixed platform phone to call Holborn, where the rest of the team are supposed to be loading up the train. They're still there. It seems that the train driver had a shipment to drop off at a storage bay nearby, and he needed help. Now they're not likely to arrive before 3am. In other words, the whole night is a write off.

We decide there's no point waiting, so we head off east to our next site, at Stratford. But the guys have to stick around until the train arrives, when the site manager might let them go.

Some staff commute daily from Northampton to spend a night like this. All forgo the company of their families, nights in the pub with their friends, occasional glimpses of the sun. One of the guys tells me about the low life expectancy of marriages among track maintenance staff …

This second site is on the Central Line between Mile End and Stratford. When we arrive there's a power failure at Mile End, so we are in for a long walk to reach the area where work's under way.

We drive to an odd rectangle of chain-link fencing around a cluster of site huts and the brick abutment of a railway bridge. After we sign in at one of the huts, we go through a door in the abutment. This leads to the Old Ford shaft. It's a fire-escape style zigzag of light metal stairs in a pit coated with soot; descending it is like descending into a coal mine, or an industrial chimney.

At the bottom we are somewhere on the curve shown on the opening spread of this article. It takes a long, long 20 minutes to walk down the tunnel over slippery pebble Ballast to where a team of nine are laying sleepers. The air tastes like it does at London Bridge after a summer shower: it tastes of dirt; the tunnel is silent apart from the drip of water

When we reach them, the team are replacing the old wooden sleepers with concrete ones. They've done seven so far tonight – we arrive just as they're laying the concrete to fix them into position. Seven is normal, the site manager says; they can do nine on a good night, though. They use a concrete that dries in 25 minutes: the first train runs an hour after the last pour.

This job has been going on for two years; they're in the tidying up stage. It's a general job – they're replacing track, sleepers, everything.

It's physically draining work. But with two consortiums competing in the labour market, workers have learned to maximise their incomes. They aren't supposed to work within 12 hours of finishing a shift without permission from Metronet. But there's a demand for them, especially on sites that operate 24 hours a day, such as the Brixton asbestos job earlier this year. One worker tells me that some people will do one shift for Metronet and then do another for Tube Lines. "They'd work eight days a week if they could," Danny says.

Despite the hardships, it's easy to understand their eagerness. The money is the main motivation, of course – wages start at £22,000 – but most people like to take pride in the job, so it must be frustrating to spend so long planning the night's events only to have so short a time to actually work. It must be frustrating for the infracos as well, to face such a massive programme and yet to take such tiny nibbles out of it. Metronet has 148 stations to refurbish in total. Closing entire lines has been proposed, but Metronet says this would require a renegotiation of its PPP deal..

We head back to the shaft at 5am, looking forward to a shower and our delayed night's sleep. Tomorrow, Danny will be back in the office. I hope he manages to stay there.

Lessons in survival

Metronet takes safety training seriously and all its workers and anyone else who wants to visit the track must have the track safety card. This is an introductory qualification only; workers get much more detailed training. The track safety training takes an hour and is tested with a multiple choice exam. About 400 people in the UK hold such a card, and I am now one of them.

My tester for the night was Ray Waterman, Metronet’s operations development manager. He’s been doing safety briefings for 37 years; his other job responsibilities include “fact-finding” and incident enquiries such as the recent White City derailment; his teams have to go in after the accident and get the track back into useable order. He worked on the White City derailment too. “It was a real mess,” he says.

Topics covered in the one-hour briefing include the Health and Safety at Work Act, Electricity at Work Regulations, and drug and alcohol rules. There are some fundamental points that Ray stresses. One is that you can always refuse to work on health and safety grounds. He also mentions the confidential instant reporting system, which is open to anyone working on track or in stations to report an incident that concerns them. They remain anonymous and their manager won’t know who called it in. The company has to investigate all complaints and reply to each in writing. The results are published in a quarterly magazine which is made available to all workers.

Between 10-15% of workforce are subject to unannounced drugs and alcohol testing. The rules are: no drugs – ever; no alcohol at all in the eight hours before starting a shift; no more than one unit per hour in the time before that, to give it time to be processed by the body (the body processes one unit per hour). This is a real restriction on track workers’ social lives – some describe it as “signing their lives away” to the company. It’s strictly enforced, and transgressors get the sack. “Safety-critical” people, will also be arrested and charged by British Transport Police.

Ray runs down the list of prohibited items for track teams. These include mobile phone earplugs, radios and stereos, food and drink. He explains that hypodermic needles can be a problem for workers at depots, where the cleaners sweep them off the trains straight onto the track. Sometimes track workers accidentally kneel on them. When they’re spotted, specially trained people have to be called to clear the area.