Britain's busiest rail station, Waterloo, is expected to open for business as normal on Tuesday after almost a month of round-the-clock engineering works and travel misery.
The major transport hub's £800 million overhaul will increase total capacity at peak times by almost a third from the end of 2018, Network Rail said.
The project to extend the station's platforms will allow longer trains to operate on suburban routes from December this year - providing more space for passengers.
Travellers have faced chaos in recent weeks because of problems including signal and points failures, which affect the part of the track that can move, as well as a minor derailment.
Over Bank Holiday Monday a signalling problem and platform closures meant the vast majority of the station was out of action with many cancellations.
But Network Rail said it expected Waterloo "to be fully reopened... for our passengers" on Tuesday.
A spokesman said: "One thousand engineers and track-side staff have worked shifts 24 hours a day for the last three-and-a-half weeks to increase capacity at Waterloo by 30% at morning and afternoon peaks from the end of next year.
"The next few hours will be a crucial part of the programme as all the new signalling is switched on and tested.
"We will be keeping passengers updated on progress of the works through tonight and into the morning.
"The work will benefit the many millions of passengers who use the station, for decades to come, turning Waterloo into a transport hub for the 21st century."
During the project, rail chiefs urged passengers to consider taking a holiday, work from home or travel earlier or later than normal.
The Federation of Small Businesses warned that traders would suffer lost income they would be unable to recover even once the work was completed.
An average of 270,000 journeys are normally made to or from Waterloo every day.
The overhaul is just one of a number of large-scale projects.
Passengers hoping to take a leisure trip on the final public holiday before Christmas will have found major changes to services out of London Bridge, London Euston, London Liverpool Street and London Paddington, as well as Waterloo.
The work at Euston will be one of the first major physical projects in preparation for the HS2 high-speed railway as a new power supply is installed at the station.