Passengers using a number of rail lines face disruption over the May Day bank holiday weekend due to engineering work.
Virgin Trains, Great Western Railway and TransPennine Express are among the operators affected.
Network Rail (NR), which manages Britain's rail track and major stations, claimed it will be "one of the least disruptive bank holidays for railway travel for many years".
It said £33 million of improvement work will be carried out over the weekend, when fewer than half the usual number of passengers are expected to travel.
Buses will replace trains between Glasgow Central and various parts of north-west England from April 30 to May 2 due to work on the West Coast Main Line.
Signalling improvements on the northern part of the Midland Main Line mean major alterations to services, including replacement buses running between Manchester Piccadilly and Sheffield on May 1.
London Paddington will see reduced services over the weekend as Crossrail and electrification work continues.
No Gatwick Express services between the airport and London Victoria will operate during the bank holiday. Fast, direct services will run to and from London Bridge instead.
More than 96% of the rail network will be unaffected by the engineering work, NR said.
The company's chief executive, Mark Carne, claimed this was "good news for passengers".
He said: "We're continuing with our huge investment programme and we have a lot of work to do this weekend, but we've planned it as far as possible to minimise disruption.
"Over 11,000 members of the railway's orange army will be out working this bank holiday to build a bigger, better railway as part of our £40 billion railway upgrade plan all aimed at providing better, more reliable journeys for passengers and businesses across Britain."