The task of restoring and rejuvenating an important part of south London’s Victorian railway heritage is not without its complexities. As structural and civil engineers on this project, our biggest challenge lay in the re-purposing of 8,500sqm of existing railway arches while ensuring the safe running of the train lines above. Retained façades were to be incorporated into three of the five buildings, with a sizeable new basement to be built under the water level of the adjacent River Thames.
Complex site-wide infrastructure, including the railway’s 200 year-old drainage points, also presented some interesting civil engineering challenges for the team.
One of the keys to the success of Borough Yards lies in its accessibility. Lanes and pathways weave between the brick rail viaducts to create new links between Borough and Bankside. This required significant structural alterations to be made to the existing arches. Both temporary and permanent works were used, including the partial removal of two existing sections supporting the live railway overhead. These were to be replaced with carefully installed steel arch supports to form the new Dirty Lane walkway. The cost of this work alone was £5m and required meticulous liaison with the Network Rail Asset Protection Team.
Significant studies were carried out to determine the most suitable construction approach for the development. The coordination of temporary works retaining the existing masonry façades and new basement were a key consideration, including the load transfer sequence from the temporary supports to the new permanent structures. Not only was waterproofing required for the sizeable basement built below the groundwater table, but it also called for a design capable of resisting hydrostatic uplift during construction.
The tricky task of readjusting existing service trenches to allow for new requirements was also undertaken. This infrastructure included water, gas, electricity, data, district heating and drainage system, while also picking up the existing railway’s 200-year-old track drainage points.
Building Information Models (BIM) covering all construction details and sequencing were used for coordination purposes, and to prove the buildability of the scheme and eliminate potential onsite construction issues. Services drawings were produced to test the feasibility of squeezing multiple services into the tight constraints of the site. This also helped to avoid hindering structural proposals and ensured efficient on-site installation. The services layout also took into consideration any possible future structural developments and foundation requirements.
Ultimately, Borough Yards was complex, enthralling and one of our most unique developments yet.