Network Rail is due to announce its preferred route for a new high-speed railway line linking London and the north of England and possibly Scotland.
Network Rail has proposed a new £34bn ($55bn) high-speed railway line linking Scotland and London.
There is speculation that the company that runs Britain's rail infrastructure will favour building the new line up the country's west coast.
The line will go via Birmingham and Manchester, getting passengers from Glasgow to London in just two hours and 16 minutes, the rail firm said.
This could mean rail journey times between London and Glasgow taking as little as two and a half hours.
The proposed new line would become the country's second high-speed rail link after the line that runs from London St Pancras to the Channel Tunnel.
Network Rail will announce its decision at 0945 BST.
Network Rail rejected routes going via the Midlands or the east of England.
However, any final decision will be made by the government.
However, any final decision on the proposed line will be made by the government.
That could depend heavily on how much it costs, said the BBC's transport correspondent, Richard Scott.
That could depend heavily on how much it costs, said the BBC's transport correspondent, Richard Scott.
Easing pressure
The proposed new line would become the country's second high-speed rail link after the line that runs from London St Pancras to the Channel Tunnel, used primarily by the Eurostar that runs to Paris and Brussels.
Network Rail says the new line is required to ease the pressure on Britain's railways. It says passenger numbers have rocketed by 40% over the past decade, and that by 2024 many existing lines will be at full capacity.
Transport Secretary Lord Adonis told the BBC that high-speed links are vital for the future.
"Virtually every other major developed country in the world has now built high-speed lines. And all those that started building them between their major cities have extended them now to cover large parts of their country," he said.
"There's a general acceptance that if we're going to meet additional transport demand over the next 40 or 50 years, then that can't be by building more motorways or having a lot more short-haul aviation."
Trains on any new line could travel at speeds of more than 180 miles per hour.
However, if it is built along the west coast via Birmingham and Manchester, it would mean cities like Sheffield, Leeds and Newcastle missing out.
Christian Wolmar, a rail analyst, said the line might not give the best value for money.
Debate
"I think there's a big debate to be had. Do we really need a high-speed line which will absorb an enormous amount of resources, or would the money be better spent put into the existing network?
"Something has to be done, there's not enough capacity on the rail network and there is increasing demand.
"But whether it should be a new high speed line or improving existing services is a matter for debate."
The regions and cities that may be a part of the new high-speed line have been actively campaigning for it to pass through their areas.
"I think high-speed rail is gaining ground right across the world really because people can see that if you link all the major cities up with this kind of fast service it does help," said Roger Jones, the director of the North West Rail Campaign.
"It's really the future. That's how we need to be travelling between our cities," he added.
