The tidal location of the river created a significant flood risk and required careful environmental planning. Complex signal structures on constrained bridge crossings introduced additional engineering and approval challenges, while the proximity to a dual carriageway demanded strict traffic management. The site’s ecological sensitivity, including nesting birds and protected wildlife, limited construction activities, alongside the need to account for structural load and thermal expansion. The exposed installation also presented risks of vandalism and unauthorised access.

• Special Engineering Difficulties (SED) included constrained bridge crossings requiring Horizontal Directional Drilling (HDD) beneath roads
• Potential for flooding due to the river’s tidal nature necessitated placing the pipe bridge above the bridge soffit and within the protection of the Thames Estuary flood defences. Polytetrafluoroethylene (PTFE) sliding bearings and expansion joints were used to accommodate thermal and structural movement without compromising flood resilience