This paper discusses the demolition of the central suspended span of the Huntingdon Railway Viaduct, which crosses the East Coast Main Line on the west side of the Cambridgeshire town. The structure became redundant in December 2019 when a new offline section of the A14 was opened to the south of the town as part of a National Highways improvement scheme.
The ageing viaduct had become a challenging and expensive asset to maintain, but demolition presented many difficulties, including the need to limit disruption to the railway. The eventual removal of the entire viaduct will bring a significant environmental improvement within Huntingdon, and presents an opportunity to restructure the local road network in the area.
The logistical and engineering challenges presented by the removal of the central span, where traditional demolition methods were unsuitable, were substantial. These included making sure that a series of known and potential structural defects, such as a defective post-tensioning system and weak half-joints, did not cause disruption or pose a safety risk to the local community or critical transport routes that the viaduct crosses.
Rigorous planning, assessment, design and (de)construction allowed these risks to be effectively mitigated. Demolition of the central suspended span commenced in December 2019 and was completed in August 2020.