The main rail line from East Anglia into London is to be closed for ten days over Christmas for major engineering work to replace power lines that been in place for more than sixty years.
There will also be weekend work between October and December when buses will replace trains.
Network Rail engineers are spending the equivalent of 20,000 hours replacing just over 6 miles of overhead wire at Ilford as part of a £250m project to upgrade the wiring system on the busy mainline.
Once completed, the stretch from Chelmsford to Seven Kings will have had the new wire installed, with the aim of few train delays.
The wires and structures that are currently in place were installed in the 1950s and the system is one of the oldest in the country.
At the same time there will be work on the new Elizabeth Crossrail line which is due to open at the end of 2018.
There will be no rail service between Shenfield in Essex and London Liverpool Street from Saturday 23 December until Monday 1 January.
Buses will link Shenfield with the Newbury Park Underground station on the Central Line.
That will affect all trains running from places like Colchester, Harwich, Ipswich and Norwich.
There will also be various line closures most weekends from 21 October with details on the Greater Anglia website.
When complete, the Elizabeth line will increase central London’s rail capacity by 10% and bring 1.5 million extra people within 45 minutes of central London.