Blueprint for Waterloo railway services launched
A blueprint for the future of railway services from Waterloo to the south and west of England over the next 30 years has been published.
The Wessex Route Plan includes ideas for double-deck carriages, faster trains and new flyovers and platforms.
The report outlines how the network could cope with a forecast growth of 40% on main line services.
Jake Kelly, development director at South West Trains, said the plans tackled the "big issue of capacity".
The report by the Network Rail-South West Trains Alliance outlines proposals for lines from London Waterloo to Reading, Southampton, Weymouth, Portsmouth and Exeter. It also includes suburban services in London and Surrey.
The companies describe it as among the most congested sections of the network with more than 55 trains arriving at London Waterloo every hour and a forecast growth of 40% on main line services over the next 30 years.
The draft study identifies priorities as far ahead as 2043. The cost of the plans has not yet been fully calculated.
It suggests extra track from Surbiton to Clapham Junction, trains travelling at up to 125mph, flyovers at Woking and Basingstoke and electrification of the line to Salisbury.
Mr Kelly said: "These challenges are difficult, that's why we have to start planning them now.
"It will be expensive, but we are determined to make it as cost effective as we can."
Mark Miller of the Three Rivers Rail Partnership, which represents train uses in the Salisbury area, described the proposals as "very realistic".
"Bit by bit we're getting the infrastructure and investment we need," he added.
The draft Wessex Route Study is open for public consultation with the final version due to be published next summer.
Paul Clifton - BBC South Transport Correspondent
Waterloo Station, by far the busiest London terminus, is bursting at the seams.
The railway is already planning bigger platforms to handle longer trains. And it is resurrecting the former Eurostar station.
But it is not enough. In the longer term, the station simply will not cope with rising demand from commuters.
That's why we see some radical ideas being touted.
Double-decker trains? Fabulously expensive, given how many Victorian bridges would have to be rebuilt. They are unlikely, but not impossible.
Flyovers at Woking and Basingstoke? Definitely, they would increase track capacity and ease bottlenecks.
Electrification to Salisbury? Eventually, once today's diesel trains wear out.
This is long-term planning, with some "blue sky thinking" - just don't expect any of it to happen anytime soon.