Buses will replace trains on some key routes over the Christmas period, rail companies announced today.
Among routes where passengers will have to switch to buses are between Reading and Wokingham in Berkshire, on some services in Essex and on some trains to and from Glasgow Central station.
But the number of replacement buses has halved compared with Christmas last year, the Association of Train Operating Companies (Atoc) and Network Rail (NR) said.
And they added that about 54,000 more trains would be running over the Christmas and new year period - a 35% increase on the 2010/11 festive season.
The two companies said that works costing £109 million were being carried out on the network from December 24 to January 2.
The key works are:
:: READING, BERKSHIRE - As part of the £850 million redevelopment of the railway at Reading, a new bridge will be slid into position and widespread platform and track improvements will be put in place.
Buses will replace trains between Reading and Wokingham from Tuesday December 27 to Friday December 30. Main line services between Reading and London Paddington are unaffected;
:: BIRMINGHAM - As part of the redevelopment of Birmingham New Street station, Network Rail (NR) will be carrying out various works, including the installation of a footbridge. A reduced service will operate on local routes via Birmingham New Street on Tuesday December 27 and Wednesday December 28;
:: ILFORD/EAST LONDON - NR will be installing new overhead electrical lines as part of a £200 million project to replace outdated equipment on the line between Liverpool Street station in London and Chelmsford in Essex.
Replacement buses will connect passengers with Newbury Park on the Tube's Central line for onward journeys to Stratford/Liverpool Street on Tuesday December 27 and from Saturday December 31 to Monday January 2;
:: PAISLEY/EDINBURGH - NR is moving signalling control for the stretch of track to the new purpose-built West Coast Signalling Centre as part of a UK-wide programme of resignalling.
Buses will replace trains on some routes to and from Glasgow Central from Tuesday December 27 to Friday December 30. On December 27 only, a reduced service will run between Edinburgh and Haymarket.
Atoc chief executive Michael Roberts said: "A significant amount of planning goes into ensuring that every year we minimise the number of people affected by disruption caused by improvement works.
"This year, we have been able to reduce drastically the number of people who will have to get on to a replacement bus. Train companies have been working closely with NR to make sure that we keep people on trains as much as possible."
NR's network operations managing director Robin Gisby said: "We're doing a lot of work this year to improve Britain's railway, but the overall effect on passengers is much lower than in previous years.
"Passengers will see more trains, fewer buses and a better service this Christmas holiday period as our vital improvement work uses new techniques and equipment that reduces the impact on train services. This will be the model for the years ahead as we invest heavily to build a bigger, better railway and support Britain's economic growth."