Signalling Solutions Ltd., a 50-50 joint venture company formed by Alstom Transport and Balfour Beatty Rail Projects, received a $12.5 million contract from Network Rail (the U.K. main line infrastructure operator) to replace three relay interlockings with Alstom's Smartlock 400T technology in the Southampton area of southern England by April 2011.

The methodology being applied is known as "interfaced interlocking." The life-expired interlockings are replaced with the new interlocking system and are then interfaced with the existing trackside equipment that is left in palce. This technique forms a key part of Network Rail's plans for resignalling projects in the U.K., as it offers significant advantages over entire replacement schemes in terms of rapidity of installation, lower costs and less disruption to the railway. Furthermore, the Smartlock interlocking technology gives the potential for ERTMS to be overlaid at a later date if required.

Between December 24 and 29, Signalling Solutions carried out some early works on the Southampton project, installing and testing interlocking tie cables. Final commissioning of the new relay interlockings is planned in April 2011. This is the third interfaced interlocking contract awarded to Signalling Solutions in the last three months.