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Building set to resume on Tesco tunnel collapse store

Work has been halted for almost three years since the tunnel failure at Gerrards Cross

The steel frame to support Tesco’s Gerrards Cross store will be torn down next month making way for a redesigned structure to be put in its place.

The superstore, due to be opened in September 2010, is being built by Costain over a man-made tunnel spanning a 320 m section of the Chiltern Railways line in Buckinghamshire.

No construction work has taken place since a 30 m section of the tunnel collapsed in June 2005.
A spokesman for the supermarket firm said: “We want to start enabling works over the next few weeks and we will continue to work towards detailed design approval from Network Rail for the store.”
Next month, Tesco plans to carry out advance works including the construction of a temporary bridge to allow plant across the railway line and setting up a crane access ramp.

In April, new tunnel units will be added to the existing framework where the collapse occurred. These units will then be used as a cast for the new reinforced concrete arch.

The store will be constructed using the original design but with modified foundations.

But before construction can begin in earnest Tesco needs to re-obtain planning permission for a conveyor to carry fill material from the railway line to the site.

Buckinghamshire County Council has deferred a decision on the conveyor three times.

At last week’s meeting a legal adviser said that since a consultation into the conveyor is still underway it would be finan-cially risky to make a decision on it.

The Tesco spokesman said: “We want to bring the materials in by rail rather than by road, since we’d need more than 10,000 lorries. Also, it’s more environmentally friendly.

“The consultation ends in two weeks and we hope it’s all resolved soon.”

So far Network Rail has given approval in principle for new consultant Scott Wilson’s reworked design for the tunnel and superstore.

It is hoped that detailed design approval will be obtained this June.

The collapse

Suffolk firm Jackson Civil Engineering was working on the tunnel when it collapsed. White Young Green was the consultant.

Jackson was backfilling over a 320 m tunnel it had built on the Chiltern Railways line for the construction of a new Tesco store when a 30 m long section collapsed, causing two months of rail chaos.

The retail giant then turned to Costain to carry out a three-month review of the £25 million scheme to decide on the future of the Buckinghamshire project.

Timetable for Gerrard’s Cross works

February 2008

Obtain form C approval from Network Rail for advanced works
Removal of the steel store frame for the store
Construction of a temporary bridge to allow plan across the railway line
Construction of a crane access ramp/platform

April 2008

Bring new tunnel segments to the site
Installation of the remaining tunnel segments
Removal of excess fill material from the site
Import of additional fill material to complete tunnel

June 2008

Obtain form B approval from Network Rail for detailed design of permanent works
Permanent construction begins on the tunnel
Pouring of concrete over arches
Import of additional fill material to complete tunnel

August 2009

Works to improve the road at the front of the store

February 2010

Station reinstatement process begins

March 2010

Store construction begins
Second stage of road improvements begin

July 2010

Road improvements completed

August 2010

Station reinstatement completed

September 2010

New store opens