The west coast main line railway in the UK is one of the busiest in the world, carrying around 75 million passengers each year and more than 40 per cent of the country’s freight on the 640km route between London and Glasgow.

The line was built in the 1840s but has not received any significant investment since the 1960s, which means the infrastructure is creaking. But that is now changing. For the past few years the line has been the focus of Europe’s largest rail renewal scheme and one of the most challenging rail engineering programmes in the world.

The scale of the £8 billion project is mind-boggling. As well as the renewal of 1,600km of track, some 3,500 signals are being moved, updated or installed, requiring more than 3,000km of signalling cable. Over 550km of new security fencing is being erected and 119 bridges have been built or reconstructed.

All this is being done while keeping the line functioning, allowing more than 2,000 train movements to continue each day. To achieve this a vast army of engineers descends onto the line each weekend; on average 10,000 workers will be toiling on the project every Saturday and Sunday at up to 400 different sites, and together they have so far racked up more than 60 million man hours.

Each Friday, thousands of engineering trains deliver workers and materials after the train services have stopped. Work is carried out over the weekend before everything is handed back to the operators in time for the first train on Monday morning. Its like having your car engine taken apart and reassembled every weekend.