As part of the Thameslink Programme there is extensive civil engineering work required between London Bridge and Deptford stations. As part of the early works we were engaged by Erith Contractors to develop a temporary works scheme to allow the demolition of a masonry viaduct.
The initial scheme involved stabilising several bays of the viaduct as hard points to minimise the risk of progressive collapse of the arches as a result of removing the lateral support. We felt that there was an option where the viaduct could be demolished by sequentially removing ll from the top of the arches and then cutting the arches back from the face in a staggered pro le.
In order to verify this we undertook a series of stability analyses for the viaduct using both hand calculation and specialist arch stability software. We were able to develop a safe system for demolishing these arches without providing any physical temporary works. We were then able to demonstrate to Skanska and Network Rail that the proposals were both safe and robust and that they did not imperil the live railway on the immedi- ately adjacent viaduct.