Railway lines between King's Lynn and London will be blocked this Easter bank holiday weekend.
Network Rail is planning to spend £83 million on upgrades throughout the country between Good Friday (April 15) and Easter Monday (April 18) alone.
Some of the works are taking place in the East of England, blocking lines through Cambridgeshire, Essex and Hertfordshire.
Greater Anglia passengers are set to face a full line closure all weekend at Bishop's Stortford - between Cambridge and London Liverpool Street.
A rail replacement bus will run between Stansted Airport and Waltham Cross, where passengers can pick up services into London Liverpool Street.
This is because Network Rail is replacing track in Hertfordshire across select weekends between March 5 and June 12.
The company has said that more than one mile of track and 11 points will be replaced over the Easter bank holiday weekend.
Ellie Burrows, the Network Rail route director, said: "This year, most of the network will be available for passengers to enjoy days out by rail throughout the Easter holidays.
"Those planning to travel on the West Anglia line and those planning to travel to Stansted should check how their journey might be affected by the works.
"I’d like to thank passengers for their patience while we carry out this important work to renew the track to improve reliability on this busy line."
On Easter Sunday (April 17), works are taking place on the line between Ely and King's Lynn.
There will be no Great Northern or Greater Anglia trains to Littleport, Downham Market, Watlington or King's Lynn when the line is closed.
A rail replacement bus is scheduled to run.
Elsewhere on the network, Thameslink and Great Northern have warned that amended Saturday timetables will be in place on Good Friday and Easter Monday.
Buses will replace some early morning and late night Thameslink and Great Northern trains in Cambridgeshire.
In London, the Hammersmith and City line - through Liverpool Street and King's Cross St Pancras - will be shut from Good Friday until the end of Easter Monday.
The Piccadilly line will be closed between Acton Town and Heathrow Airport.
Transport for London (TfL) has said that rail replacement buses will run.
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