Carillion Demolishes And Replaces A Whole Section Of North London Line rail bridge in just three days

Given just three days of rail time possession in which to complete the demolition of the existing deck of the Camley Street rail bridge in Camden and slide in the replacement unit, Carillion had to ensure the solution chosen to complete the task was swift, safe and reliable.

Faced with demolishing and replacing a whole section of the rail bridge as part of its North London Line upgrade contract, Carillion opted for a falsework solution from RMD Kwikform that could cope with its very tight programme demands.

Working in the extremely tight confines of the Camley Street location, Carillion had to complete the works whilst keeping road access open for local residents and businesses. In order to be able to complete the deck replacement in the three day possession window, the new deck structure had to be constructed offline, right next to the existing bridge.

In order to achieve this, RMD Kwikform and Carillion engineers designed a dual system for the slide path of the deck, using Rapidshor and Megashor heavy-duty shoring equipment. The Rapidshor, together with RMD Kwikform’s steel Superslim soldiers formed the main bridge support, crash deck and access for the new deck to be poured and cast in-situ.

Constructed within the Rapidshor falsework lattice and a heavy duty Megashor shoring system was devised to support large steel beams that enabled the bridge deck to be slid into place.

Explaining the challenges and phases of the project, Carillion agent, Ray Rushe said: “There were three distinct phases to this project which were all critical to its success. The first was to design and erect a falsework and slide path system. This had to be located in the extremely tight confines of the space available on Camley Street and be capable of withstand the pressures of the 353 tonne concrete deck. It also had to be an inherently safe system of work.

“The second phase was the deck pour. Again here we had to cope with the very restricted space and the logistics of getting concrete supplied to site and pumped up to the deck. Thankfully we were able to fit a mobile pumping unit into the location that could be fed by the concrete mixers. Once the deck was cast and cured, we were able to enter into the final phase of the demolition and slide.

“The slide itself was 13.2 metres in total. Having possession of that part of the line for three days, we first had to remove the existing number two line tracks and then demolish the deck. This took a full day, leaving just two days to slide the new deck into place, secure it to the remaining bridge structure, relay and test the tracks.

“When we were ready to slide the bridge section, we used the Megashor solution and hydraulic jacks to raise the height of the deck. The deck was then pushed forwards using a hydraulic ram. We had initially expected this phase to take 4-5 hours, but it was completed much quicker as the slide mechanism proved to be very efficient and easy to use.

“Once in the right location the deck was lowered into place and secured with the tracks remounted. The whole process took just over two days, leaving plenty of time for testing and releasing the track for train and passenger use, limiting disruption to travel.”