By Peter Plisner
BBC Midlands Today Transport Correspondent
Journey times between Birmingham and London could be cut to 46 minutes
Network Rail has warned of a "looming capacity crisis" on the rail route between the Midlands and London, unless a high-speed line is built.
A new report from the rail infrastructure company claims that track capacity on the West Coast Main Line will have run out by 2020.
The prediction comes despite the recent completion of a £9bn modernisation of the line.
According to Network Rail, if a high-speed line is built, journey times between Birmingham and London would be reduced to just 46 minutes. It currently it takes about an hour and 20 minutes.
A new line would also help to relieve existing routes to London.
But a high-speed line just to Birmingham would not be viable, according to Network Rail.
Instead, it is suggesting that the city be part of a network of high-speed routes, providing fast links from the Midlands to other major cities, including Manchester and Glasgow. The report suggests that such a network could cost about £35bn.
The UK lags behind some of the rest of Europe when it comes to high-speed rail. France and Spain already have well-developed networks and in other countries new lines are under construction.
A revamped New Street station will not be able to house high-speed trains
Early next year a further report will be published, this time from the High Speed Two (HS2), a company set up by the government to plan a high-speed rail network, which is being led by a former civil servant, Sir David Rowlands.
The Network Rail study is expected to feed into the final HS2 report.
There is little doubt that high-speed rail will come to the Midlands first. Transport Secretary Lord Adonis has said as much in previous statements.
He is a big fan of high-speed rail, having travelled the world, riding on different systems, and has suggested an approach that would see a high-speed network built incrementally.
Recently there has been much debate about where the high-speed route should go when it comes to the Midlands.
Some favour a station in Birmingham city centre, while others say it should go through Birmingham International station to link with the airport and NEC.
The report does not favour either option, instead it talks of the need for a new station for Birmingham generally.
Despite a soon-to-start £600m modernisation programme, bosses at Network Rail maintain that the new-look New Street station will not have the capacity for high-speed trains. No suggestions have been made by them about where the new Birmingham station should be sited.
Other aspects of the route will also have to be debated.
Transport Secretary Lord Adonis has said he wants high-speed rail in the UK
Delays caused by objectors slowed down progress on the first UK high-speed route from London to the Channel Tunnel. Eventually, the new line went underground through London and then, adjacent to motorways, through Kent.
A similar routing option is likely with the new routes, which could follow either the M40 or M1 corridors.
Funding remains one of the biggest issues. Although plans for high-speed rail enjoy cross-party support, building new lines will not be cheap.
Even the line to the West Midlands is estimated to cost about £10bn. Most agree that new lines should be funded through a mixture of public and private sector money.
Lord Adonis has maintained that when it comes to high-speed rail in the UK it is a case of "when, not if".
A public consultation exercise is expected to take place early next year, following the publication of the final report from HS2.