Complex Tunnel Excavation Complete

Wednesday, 6 May 2009

Excavation for a tunnel linking two Regent Street sites formerly occupied by the Regent Palace Hotel and the Café Royal is complete.

The tunnel being built beneath Glasshouse Street will allow goods and materials to be ferried from a new 12,000 sq ft service area being created on the Regent Palace Hotel site to the new luxury hotel replacing the Café Royal.  The creation of this single service yard will free up space for the public realm improvements that are a vital part of the Crown Estate's plans to open up this end of Regent Street.

Now the excavation to 7.5m below road level is complete, work will begin building the tunnel and reinstating a Victorian sewer that had to be demolished as part of the excavation.  Sewage running along the Glasshouse Street sewer was diverted along Air Street during this time.

The excavation has been complicated by unforeseen challenges, primarily the discovery of a large number of unrecorded services below the road.  These included extensive fibre optic cabling, a cast iron pipe from circa 1830 that is likely to have been part of a hydraulic power system used to run lifts, as well as what may have been two old gas mains feeding gas-powered lights in the early 1900s.  The discovery of the extra services forced a redesign of the temporary works needed for the excavation.

Stanhope project director Paul Hargreaves said:  "The services ended up covering 75 percent of the width of the tunnel, posing the design team a considerable challenge in finding a way to install the temporary works without disturbing any of the cables or pipes.  That they were able to come up with a workable solution is a testament to their hard work and resourcefulness."

The reformation of the road above the tunnel is due to be completed by the end of the year (2009).

Stanhope is overseeing the development on behalf of the Crown Estate, while Sir Robert McAlpine is the construction manager.