Birmingham train passengers will face disruption on some major routes due to engineering work over the Christmas and New Year period.
Affected routes include the West Coast Main Line due to work at Birmingham and the Great Western line because of improvement work at Reading in Berkshire.
But Network Rail (NR) said more trains would run this festive period than last and that fewer replacement buses would have to be laid on.
Engineering work on certain days between Thursday, December 23, and Tuesday, January 4, will affect as many as 15 of the passenger train companies.
On the West Coast line operated by Virgin Trains, some services will be disrupted due to engineering work at Birmingham New Street and further work between Wigan and Preston.
At Reading, a massive new bridge is being wheeled and jacked into place ready for more tracks and platforms to be added.
This will affect Great Western services, with buses replacing trains on several routes.
Certain direct journeys on CrossCountry lines will not run, with passengers having to make changes at Birmingham.
Work being carried out at Victoria Station in London will mean the Gatwick Express will only run early-morning services on Monday, December 27 and Tuesday 28, although half-hourly Southern train services will be available between London Victoria, East Croydon and Gatwick Airport on the two bank holiday days.
Another big London terminus - Blackfriars - will remain shut over the festive period, having closed from November 20 for work on the £5.5 billion Thameslink project. Blackfriars reopens on January 16.
Work at Stratford in east London in connection with the 2012 Olympics as well as overhead line work will mean buses have to replace trains on some National Express East Anglia routes out of Liverpool station in London.
NR said that during the period December 24 to January 3, there would be 10,000 trains more than ran in the 2009/10 festive period and over 2,500 fewer replacement buses.
More than 90% of the network will be unaffected over the 2010/11 festive period.
Overall, NR is spending £50 million and using almost 5,000 workers on festive projects this year.
NR operations and customer services director Robin Gisby said: “Thousands more trains are running this Christmas time and many thousand fewer replacement buses.
“Few main lines are affected and this work is a vital investment to deliver a bigger and better railway in the future.
“Passengers should check the details of their journey before they travel.”