A86 VERSAILLES:Travails du Tunnel
By Peter Samuel
Francois Molle, a Cofiroute spokesman in Paris told us he had spent the whole of the week talking non-stop to reporters about fire precautions planned for the Versailles A-86 tunnel. Molle was arguing that the exclusion of heavy trucks from the Versailles tunnel will remove one major source of a fire catastrophe since there will be no major loads to burn. Furthermore the double deck plan of the tunnel facilitates rescue and fire fighting. Third the Versailles tunnel being shallower has many vertical ventilation and escape shafts that were lacking in the deep Mont Blanc tunnel. Still, the company is likely to feel it prudent to thoroughly reexamine its fire plans in the light of the lessons learned from Mont Blanc. Molle says noone can predict what effect the Mont Blanc catastrophe will have.
Odds are the innovatory project will eventually proceed however. Cofiroutes second bid was selected over the rival Arys bid on the basis that Cofiroute was offering to take the whole financial risk, whereas Arys wanted extensive government guarantees. In other respects a selection committee said the two proposals were comparable.
Cofiroute first proposed the project in 1988 and there was extended state sponsored and academic research into the small-gauge tunnel concept. Cofiroute signed a concession with the state in 1995 to build two tunnels to complete a missing link in the Versailles area in the A86 ring road motorway. The first on which work started is 10.1km (6.3ml) long and will be a double-decker with 3 southbound lanes on one level, 3 northbound lanes on the other level. Clearance to the ceiling on each level is only 2.55m (84") and entry will be limited to vehicles 2m (68") high - rather like in parking buildings. Lanes will be narrow too, about 2.9m (96") and the maximum grade steep (5%) so a 70km/hr (42mph) speed limit is proposed. About 4km along there will be tunneled ramps for an interchange with the east-west expressway A13 and at about the 8km point near the Avenue de Versailles there will be provision for a future second interchange - with a radial arterial. The tunnel will terminate at the Pont Colbert end of the southern section of the A86 in a complicated but compact interchange with links to 3 other highways.
Cofiroute estimates that 85% of Paris area traffic meets the 2m (68") height limit for the east tube. Larger vehicles will be able to take the western tube, a 7.5km (4.7ml) single deck, 5m (16') headroom tunnel. This is a 2-lane, 2-way tunnel, which will have a posted speed limit of 60km/hr (37mph) and no interchange along the way.
The cars-only Versailles tube will have a 5,700 vehicles/hr capacity and the all-vehicles tube of quite similar overall diameter only 1,400 vehicles/hr capacity, that comparison indicating the potential productivity of sizing a tunnel specially for small vehicles.
Present estimated cost of the cars-only tunnel is Fr11b or about $1.8b. Construction of the second full vehicle height tunnel would only begin after completion of the first. (see TRnl#6 Aug 96 p1)
Construction of the first tunnel began late-96 but opponents of the project found a legal weakness in the Cofiroute concession and Frances highest court in Feb 98 found it was invalid on the grounds that the Ministry of Transport had failed to fully conform with European Union rules about advertising the project Europe-wide. The government ordered Cofiroute to stop work and in April 98 issued a new request for bids. (see TRnl#26 Apr 98 p13) $250m had been spent on the work with portals and approach works completed. A major tunnel boring machine was about to begin the main tunnel work, and was put in storage.
Cofiroute is an investor-owned toll road company that operates four major toll roads - A11, A10, A71 and A81. No taxpayer money was supposed to be involved in the project, but Cofiroute expects to negotiate compensation for the delays since it was the government which screwed up the concession. All this assumes of course that the present rash of US-style hyperlitigation and safety fears are gotten over. (Contact Francois Molle Cofiroute 33 1 4114 7378)