Hydrodemolition Efficiency in
Tunnel Repair Solution
The Belgian railway operator, Infrabel, ur-
gently needed to repair defective concrete
in the Biéreau tunnel just south of Brussels.
Hydrodemolition with a Conjet Robot 365
was used to selectively remove the dam-
aged and decaying concrete at record
he 875 m long, 10.5 m diameter Biéreau tunnel
forms part of the 4.4 km long dual Line 161D
railway track linking the cities of Ottignies and
Louvain-la-Neuve, 34 km south of the Belgian
The tunnel was opened in 1975 and during its near
40 years of service, the tunnel’s concrete skin had dete-
riorated and parts were falling off. There was also evi-
dence of longitudinal cracking.
It needed urgent repairs and Belgian railway opera-
tor, Infrabel, has invested more than €4M in the tunnel’s
Closing the tunnel completely was not possible due
to public transport demands in the urban area. So it was
decided the only option was to restore the tunnel in two
sections and working and repairing the concrete from one
track while trains passed by slowly on the other line.
The restricted space and necessary safety and envi-
ronment precautions were critical considerations for the
overall renovation project, which had to be completed in
just 220 days.
Extremely Restricted Working
Due to these restrictions, the restoration contractor,
Bageci, a regional branch of industrial Belgian Group CFE,
opted for the hydrodemolition technique, which uses a
very high-pressure water jet to selectively remove the
defective concrete from the walls and roof.
Bageci bought a Conjet Robot 365 with multipurpose
arm and a specially adapted feedbeam, carrying the cra-
dle and jetting lance, to fit the curvature of the tunnel
Conjet’s representative in Belgium, BPC International,
sold the hydrodemolition equipment. The company was
also responsible for service, support and spare parts sup-
ply to guarantee 24 h productivity and availability of the
A 500 kW Hammelmann S1200-48 high-pressure wa-
ter pump and the Conjet Robot were installed on flatbed
rail wagons fitted with foldable, protective walls. This al-
lowed the hydrodemolition and restoration work to be
completed on one side of the tunnel while trains could
safely pass on the opposite track.
Contractors World International Vol 6 No 1