Metre-high barriers are being installed across the entrances to the concourse of Waterloo station as part of a trial of new security measures.
The Department for Transport says that purpose of the trial is to assess the impact that the barriers may have on day-to-day operations at Waterloo and gauge the opinions of passengers and businesses that use the station.
The three-month trial is a not direct measure to enhance security, insists the DFT.
The barriers, which will be installed in the next few days, are about a metre in height and will prevent access by vehicles but still allow passengers to walk past to and from the platforms. The barriers will be opened to allow vehicle access when necessary, eg deliveries onto the concourse, and can also be opened at very short notice to allow access for emergency services.
"The potential role for such barriers is obvious, but what we want to do now is test the impact on the flow of passengers and on the station operations and businesses based within them," says transport secretary Douglas Alexander.
"It is important that we test any potential measure within authentic environments so that we can see just how they can contribute towards keeping a safe and efficient network. And of course, as with any such trial, all the feedback that we receive will be welcome and valuable when making any future decisions."