The effort is part of the government's attempts to reduce the risk of terrorist bomb attacks on the capital's transportation network.
The four-week trial, announced by the government last year following the July 7 suicide bomb attacks in London, will involve passengers using the Heathrow Express rail link from the airport to Paddington station and will be voluntary.
Passengers who agree to be screened at Paddington during the trial will pass through a metal box containing a millimeter wave-imaging technology that can detect items such as guns, ammunition or bombs hidden beneath clothing.
The checks will be carried out by armed police and are expected to take just over a minute each. Police can increase or reduce the number of checks according to the security threat level.
Luggage will also be screened, using a traditional X-ray machine, while a new high-tech closed-circuit TV camera system is being tested that alerts security staff to unattended luggage or suspicious behavior by passengers.
Transport Secretary Alistair Darling has already ruled out installing this kind of technology across the whole transport network because of the cost and disruption to commuters but he said the scanners could be effective in limited deployments at strategic points on the network.
The New York Metropolitan Transport Authority has also recently invested $212 million in upgrades to its security and surveillance systems for the city's subway network.
Thousands of cameras and sensors will be installed at platforms and subway stations as part of a sophisticated electronic surveillance and threat detection infrastructure, while mobile phone coverage will be extended underground throughout the network to aid communications in emergencies.
Andy McCue of Silicon.com reported from London.
