CONJET ASSISTS WITH CHANNEL TUNNEL REPAIRS.

2009-07-02 — Train services through the Channel Tunnel linking
Britain and France, where scheduled to be fully
restored in February 2009 following several months of
repairs after a major fire in the tunnel on 11
September 2008. A lorry caught fire on a Shuttle train
carrying heavy goods vehicles bound for France through
the 50km long northern tunnel. The fire, which spread
to other vehicles, raged for about 16 hours. The
extreme temperatures of up to 1000ºC caused extensive
damage to about 600m of the 7.6m diameter tunnel’s
concrete lining, approximately 11km in from the French
entrance.

The Channel Tunnel operator Eurotunnel awarded the
repair contract, estimated to be between €50-60M, to a
consortium of Freyssinet, Eurovia Travaux Ferroviaires
and Vinci Energies. Freyssinet was appointed to look
after the civil engineering works, while ETF would be
responsible for track and overhead wire restoration
and Vinci Energies responsible for other equipment.
The technique of hydrodemolition, which uses high-
pressure water jets to remove concrete from various
structures, was specified as the method to remove the
fire damaged concrete. Freyssinet subcontracted the
concrete removal to the specialist hydrodemolition and
industrial cleaning contractor Philip Lasserat.

For the hydrodemolition part of the repair Philippe
Lassarat hired four Conjet hydrodemolition Robots and
pumps, together with a team of experienced operators
and a project manager, from Rotterdam based Doornbos
Equipment, a specialist in the rental of ultra high-
pressure water jetting and vacuum equipment. To meet
the tight schedule Doornbos had to work three shifts
round the clock and opted to use two Conjet 364s and
two Conjet 322s. Conjet supplied specially modified
banana shaped feedbeams, which carry the jetting
nozzle, to match the curvature of the tunnel wall.

“We had to remove the damaged C45 concrete just from
the walls and roof to a depth of 30mm and managed this
at an average of 650m2/day,” says Doornbos project
manager Uwe Clausen. “The total area was about 9,500m2
over an approximate 600m length of tunnel, including
about 350m2 directly above the fire where the damage
was most severe. We removed all the fire damaged
concrete in 14 working days using four Robots. We had
to work non-stop round the clock in three 10 hours
shifts, which included an hour in and an hour out at
shift change to get through all the security.” The
Robots were supported by 350kW and 400kW pumps
operating at pressures up to 1000bar and flow of up to
240litres/min.

After the removal of the damaged concrete Philippe
Lassarat followed on repairing and replacing any fire
damaged reinforcing prior to spraying on the new
concrete lining. The various services and utilities
were then replaced before handing the tunnel back to
Eurotunnel to restart a full service of the Shuttle
trains on 10 February. Eurostar, the company that
operates the passenger trains running through the
tunnel, anticipated services would be fully restored
on 23 February.

For further information please contact:

Lars-Göran Nilsson or Carl Strömdahl

Conjet AB
P.O. Box 507
S-136 25 Haninge
Sweden.

Tel: +46-8-556 522 40
Fax: +46-8- 556 522 60
E-mail: conjet@conjet.se
Internet: www.conjet.com

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