Interviews

Heavy lifting

The reconstruction of four rail bridges in north east London in the autumn required some deft lifting work, the relocation of some residents, and an awful lot of engineering prowess across four tight possession windows. RTM speaks to Network Rail’s scheme project manager Jagjit Singh. Four weak bridges on the Gospel Oak to Barking line from north to east London had to be replaced last year to ensure Network Rail met its licence obligations, as the 120-year-old structures did not meet the published RA of the route.

Although all four – at Vansittart Road, Pevensey Road, Thorpe Road and Skeltons Lane – were identical structurally, making the work simpler than it may have been, they are also all located in residential areas with very dense housing.

This made the communications and public relations aspects of the work as big a challenge as the engineering, according to Network Rail’s scheme project manager Jagjit Singh, who said: “We wanted to maintain a good working relationship with the residents, especially when we were doing lifting work over their private property.”

Preparatory works started on site in February 2010, by which time residents had already had extensive information on the upcoming works and the fact that some of them were to be relocated to hotels if they chose, because of the noisy demolition and construction works.

Following enabling works to extend the bridges’ abutments, on Network Rail land, the main works were done over four consecutive weekends in September and October, with three possessions of 52 hours and a final one of 28 hours, during which the tracks were welded and stressed.

Singh said: “The methodology was the same for all the bridges, because all four structures were very similar – in fact they were exactly the same in terms of their construction.

“The main challenge was the location of the bridges. They were located in residential areas, with houses very close by. That created a number of issues, for instance the piling works that had to be done to extend the abutments. The piling works were done at once, and as part of that we had to do a condition survey on all the houses.

“We also had to use cranes to do lifting over the houses, so people’s property, which was a health and safety issue. That meant that up to a year before work started on site, we were liaising with the local residents. We told them exactly what we were doing, through letter-drops, a public meeting on site, and with the involvement of the local council.”

During each possession window, the engineering works went on non-stop and were often noisy, so some residents were eligible to be put up in a hotel for the weekend at Network Rail’s expense.

The principal contractor was civil engineering firm J Murphy & Sons Ltd, which used a 500-tonne crane in carefully planned locations to ensure the works did not damage the nearby houses.

Each existing bridge deck was removed in three sections, one part lifted off at a time, while the replacement bridge was fabricated and delivered in two sections. They were then lifted into position, such that the holding-down bolts for the bearings aligned with pre-formed sockets in the bearing plinths.

It was not all plain sailing – during the second weekend, 24-26 September, when both the Vanisttart Road and Pevensey Road bridges were being replaced simultaneously, one crane broke down while a section of the new bridge deck was being lifted, causing a 16-hour delay. The team managed to make up the lost time to get the works done within the tight possession window.

Patrick Shaw, project manager for Murphy, explained how the civil engineering specialists also installed the reinforced concrete piles on both sides of each bridge to support the abutments.

He said: “This was all done within a very tight period of time, as the land required to facilitate the construction of one of the abutments was not made available until five weeks before the start date for the bridge replacement works.

“The bridge replacement works were not particularly straightforward, but due to hard work and dedication of our team and our supply chain we delivered the project within the allotted timeframe.”

Singh outlined the benefits to passengers and the train operators and freight operators who use the busy line, saying: “The bridges were weak, they were built years and years ago and we had to replace them.

“If we didn’t, then in a few years time we would have had to put a TSR on the bridges, causing disruption to the schedule, and eventually we wouldn’t be able to run trains over them at all, so it was very necessary to do this work.

“It was a very successful project, taking into account the fact we replaced four bridges in this series of possessions, and the work with the local residents, and the diversion of the UK Power Networks’ services and cables.”

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