The operation is a first for the industry, which up until now has opted to take possession of tracks, during complex work programmes.
The £10m road bridge was launched across the 10 operational rail lines that form the main lines into London Bridge at Tennison Road, Norwood Junction, in south London.
Also working on the lauch were ALE – Abnormal Load Engineering Ltd working in partnership with Severfield Rowen.
Network Rail and Grahman Construction are now midway through the project to replace the original bridge with a bigger, better structure. The new bridge will have wider footways and carriageway.
Rory McFadden, Graham project manager, said: “We are delighted to have reached this major milestone on the replacement of the Tennison Road Bridge.
“Launching a 565-tonne bridge over 10 operational rail lines is quite a feat of engineering but the innovative methods used allowed for a controlled and safe installation. That said, it took a lot of preparation in advance of the actual launch.”
The original Tennison Road Bridge has spanned the main lines between London Bridge and East Croydon since 1922. The new bridge was launched into position using a hydraulic strand jack system.
Network Rail’s scheme project manager, Shane O’Connor, said: “A combination of technology and engineering expertise meant we could keep trains and passengers moving while we the bridge was launched across the tracks.
“This is the first time we’ve worked in this way – in the past the only way would have involved a complete closure of the railway, which would have caused huge disruption.”
Tennison Road Bridge is due to open for public use in spring 2015.