Federal Road Office, OFROU (Switzerland)
Belfor, Grisoni-Zaugg, Colas for the cleaning and the civil engineering works.
Fluckiger, Signal, Etavis, ACP et MZ for the repair of the equipment.
The works began with a thorough cleaning of the total length of the Alpes bore of the tunnel. The toxic soot was removed using high-pressure jet washing over several passes of a truck equipped with spray nozzles and brushes. This initial cleaning phase was followed by further clean including a neutralisation of the metal elements to remove the chlorides, which can increase the risk of corrosion. The decontamination operation lasted 15 days and was completed under the supervision of BG's 'polluted sites and soils' team with the collaboration of the Swiss laboratory EMPA for the chemical analyses.
The repair works to the 45m length of the pavements, slot gutters and tunnel render impacted by the fire lasted 12 days. The works to repair the electromechanical equipment were undertaken in the same period. The heat released by the fire caused damage to equipment up to 500m downstream of the fire site. The lighting and cableways were destroyed along with the electrical cables, plunging this section of the tunnel into darkness. The number of light fittings to be replaced was significantly higher than the number of spares held in stock, and so the spares of a neighbouring tunnel were also used. The fixed and lit signage damaged in the zone of the fire were replaced by new signs, installed during the second phase of the repair works.
Seven fans were irreparably fire- or smoke-damaged and were replaced in the autumn with new custom-made fans.
OFROU commissioned BG to undertake the following services:
- Assessment of the condition of the tunnel's Alpes bore following the fire;
- analysis of the damage; creation of a list of equipment to replace or repair;
- coordination of the repair works with the safe re-opening of the tunnel at the earliest opportunity using the available spare equipment;
- planning the acquisition of the missing equipment;
- planning the repair works to be completed in a second phase;
- developments of the financial reports required for the insurance claim.