The Intercity 125s may make way for other high speed replacements

Alistair Darling said high speed replacements for the existing Intercity 125s, longer trains and timetable efficiencies were among plans.

"There are many ways to increase capacity; we need to consider them all," he told a London rail conference.

Passenger numbers may increase by 30% over the next 20 years, experts say.

Mr Darling said the government would next year set out firm rail plans for both the short term and longer term. A rail White Paper is due to be published in 2007.

The proposals are intended to help the railways cope with record passenger numbers.

The transport secretary said replacing the high speed train fleet was a key project of his department and the process of designing a new model was already under way.

The decisions that we take now will shape the railway for generations Alistair Darling Transport secretary

He said it was for the government to decide on strategic plans for the railways because it decided how much to spend.

"The decisions that we take now will shape the railway for generations to come. We have a once and for all chance to get this right, to stop playing catch-up and to plan ahead like any other business," he said.

He said train layout and length and turnarounds, particularly at mainline stations, as well as looking at double-decker trains were among considerations.

"What works will vary across the country," he said.

High-speed link

Mr Darling said the government needed to consider whether with the completion of the Channel Tunnel Rail Link there should be a high speed line from London to the north.

"But this would be a massive project and we would need to be sure that we achieve the right solution," he said.

"We cannot be in the business of carting fresh air around the country. Any healthy, confident business should be prepared to look at the services it provides and consider where there is demand and how best to meet it."

While the government has been eager to point out that the railways are expanding, there are fears that services are being cut and that capacity has reached its full limit.

Shadow transport secretary Chris Grayling told the London conference rail improvements were not being carried out as planned, despite a five-fold rise in public subsidy for them.

He said that virtually all rail projects set out in a 10-year plan in 2000 "seem to have disappeared into the ether".

Future vision

He said there were concerns the Department of Transport's "micromanagement", or over management, of the railways would leave no room for innovation and that it was not the politician's job to run the railways.

"I don't suppose Alistair Darling entered politics with the goal of becoming a slimmer, and Scottish version of the Fat Controller. But in far too many ways, that is what he has become," he said.

"Our job should be rather different. It is to have a vision for our nation's future and its infrastructure, and a strategy for getting there."

The RMT transport union said it welcomed new investment and a vision for long-term growth.

But RMT general secretary Bob Crow added that a growing role was needed for every part of the network, including rural rail.

He also said that "more than �800m of public money" was "already sucked out of the industry every year by the private sector".

"If the vision outlined today is not to go the same way as the government's now forgotten 10-year plan, its strategy must include re-integration under public ownership," he added.