Location

Stratford Station, London, E15 1AZ

Client

Network Rail

Project Brief

As project is part of the North London line upgrade works for the 2012 Olympics Carillion Trenchless Solutions (CTS) are diverting existing the sewer mains on the London Overground Stratford to Richmond line.

The main line at Caledonian Road Station is located in a deep cutting in between large retaining walls, which are over 50 years old and are strutted with oak beams which are required to stay undisturbed as any damaged or movement could result in potential failures of the retaining walls and surrounding infrastructure.

Solution

CTS, together with Network Rail decided on an installation under the structures using guided auger bore trenchless methods (as open cut drainage was not suitable). They had originally intended to sink Marshalls Civils & Drainage standard 3000mm and 2000mm caissons, as drive and reception pits but this method was revised to cofferdams as the electric and signaling cables alongside required support during the operation.

CTS as recommended by Network Rail designers used Marshalls Civils & Drainage caisson manhole units which are suitable for the very high track loadings compared to standard manholes.

Eight cofferdams were installed along one mile of track with the use of 450mm and 600mm jacking pipes so not to disturb the reinforcements for the retaining walls, which were completed with live railway track running alongside the construction site.

Stratford Station London