Diverting a large water main in a challenging, densely populated urban environment

Euston 42” Trunk Main Diversion (Phase 1)

High Speed 2 (HS2) Rail Phase 1 will impact approximately 50 km of Thames Water’s pipes in London. This includes a 42” diameter cast iron trunk main, affected in several places by extensive upgrades at and around Euston Railway Station.

Constructed in 1925, the water main was one of the top five most critical obstacles along HS2’s route and required a 2 km diversion to accommodate it. However, finding a route through the utility congested streets of London and identifying connection points to the rest of the existing main presented a significant challenge. During Phase 1 our team worked closely with Thames Water and HS2, to develop an innovative solution that improved buildability, reduced construction health & safety risks and minimised disruption.

The team analysed utilities’ record drawings, non-intrusive surveys and trial holes reports to identify a route that avoided busy road junctions, deep excavations and used connection points at existing structures. By specifying a boltless ductile iron pipe system for ease of construction and carrying out digital assembly rehearsals using 4D BIM, the design team saved hundreds of hours of confined space working and effectively communicated health and safety risks to the workforce.