X-ray screening and body scanners are among technology being tested to boost security on the UK rail network, Alistair Darling has said.
Scanner trials will begin on Heathrow Express platforms
The transport secretary told a conference that full airport-style security was impossible at UK stations.
But scanners which can screen for weapons and explosives would be trialled at some stations.
Advanced CCTV meant to spot suspicious behaviour has been tried on the London Tube, but has proved unreliable so far.
The conference, at the QEII centre in London, is examining transport security in the wake of the bomb blasts on London's transport network on 7 July, which killed 52 people and injured 700.
Public transport managers and security experts from around the world are among those attending.
Mr Darling said that various new systems which could help identify potential suicide bombers were being tested on the rail and underground networks.
Trials of a millimetre wave scanner - which screens for traces of explosives and concealed weapons - and X-ray machines would begin in 2006 on Heathrow Express platforms, he said.
BBC News Home Affairs Correspondent Danny Shaw said there were no stops on the Heathrow Express between Paddington in west London and the airport, so tighter security was easier to administer.
The equipment will also be trialled on the London Underground network, according to the Department of Transport.
Sophisticated new "intelligence vision" CCTV technology, which automatically spots suspicious behaviour, was already being tested, Mr Darling added.
But a spokesman for London Underground said that when it tested the system at London's Liverpool Street station in 2003 it had a tendency to "falsely alarm", and was dropped.
However LU was watching a new trial of an updated version of the system on the New York subway with interest, he added.
The transport secretary told the conference the "closed system" of security screening at airports - where all passengers are checked before entering a restricted area - boosted public confidence.
"But because we know that terrorists will go after what they see as easier targets, as they did in Madrid, Moscow and London here, we need to do more than that," he said.
"You cannot have a completely closed system on the underground or the railways for instance - it just wouldn't work."
With 11,500 miles of track in Britain and 2,500 railway stations, replicating airport-style security was impossible, he said.
Travel writer Christian Wolmar said Mr Darling's speech had sent out a mixed message.
"He was saying, on the one hand, that it's impossible to protect railway systems and, on the other hand, he was saying that we have to try out this new technology," he said.
"I think there should be a clearer message which basically says we have to accept that there's a very, very small risk that something happens to any particular individual.
"Essentially, from a transport point of view, there's not much that we can do."
Human rights campaigners, meanwhile, have warned that young men from ethnic minorities must not be targeted by passenger screening.
"Public safety can be enhanced by passenger screening but police must not heighten tensions by targeting young men from ethnic minorities," Liberty director Shami Chakrabarti said.
London Underground chief operating officer Mike Brown welcomed the trials but said the technology was not yet at the stage of "being deployed sensibly while also being able to move vast numbers of people around London".
The three-day conference is also expected to be addressed by the head of the Madrid Metro who will outline the steps that have been taken to prevent further terrorist attacks in the city.
In March 2003, 191 people were killed and at least 1,800 injured when 10 bombs exploded on four packed early-morning commuter trains in the Spanish capital.