Thousands of rail passengers are facing ten days of severe disruption as work to build a new £900m station at Reading reaches its most crucial stage.
Lines will close and passengers are warned journeys over Easter could take an hour and a half longer.
It means no direct services from places like Swindon, Oxford and Newbury to London. Trains from Bournemouth and Southampton to the north will also be badly hit.
When the project is complete it will increase capacity and ease delays at the most overcrowded and congested station on the network.
An army of workers will move in later tonight. So many will be on site 6, 000 hotel rooms have been booked over the week to accommodate them.
Our Transport Correspondent Mike Pearse has been behind the scenes ahead of the of the weekend work. He speaks to Mark Hopwood from First Great Western, Jocelyn Pearson from Passenger Focus. Matt Jackson from Network Rail and Nazim Hussain.