As reported in previous editions of the IRAM Newsletter, CNRS-INSU had contracted to a consortium of engineering companies led by SCETAUROUTE, Lyon, a comprehensive study of new ways to access the Plateau de Bure.
Such a study became necessary after it was decided that the old cable car system between Enclus and the Observatory would be reconstructed only as a `blondin', i.e. as a system exclusively foreseen for the transport of materials, consumables etc. Whereas the old system was operated, maintained, and controlled according to the legislation for `téléphériques de service', the modified system will adhere to a different legislation, the `directive machine'. The necessary changes are being completed right now, and after a series of controls at component level, the cable car will soon be tested at system level according to this new legislation. In June this year it should be ready to transport materials to the station.
This leaves the problem of finding a new transport system for people. The initial SCETAUROUTE study had identified 10 different options, including new cable car systems, telecabin systems, and two `funiculaire' solutions, some of these combined with a piste at lower altitudes.
In general terms, the access problem consists of three different parts. A first section between 1500m altitude where several public roads arrive which are kept open throughout the entire year, and about 2300-2400m, with a relatively modest slope between these two levels. Then comes the `falaise', an almost vertical wall of 150-200m height, followed by a third, virtually flat part on the Plateau itself. Its length varies between 300 and 800m, depending on where one arrives at the level of the Plateau.
The problems arising from meteorological parameters like temperature, humidity, cloudiness, dense fog, and in particular rapid changes of some or all of these parameters in less than 30 minutes, are particularly severe in section 2 and 3, i.e. on the Plateau itself and in the zone of the `falaise'. The consensus is that of all the means of transport considered, an inclined elevator (=`funiculaire') would offer the maximum safety, especially as it would run for a large part underground in a tunnel. It has therefore been proposed to build such a system, starting at 2300-2400m altitude and going from there to the Observatory (or very close to it).
This leaves open the question of how to overcome the remaining section between about 1500m and the starting point of the `funiculaire'? In this context must be mentioned the strong interest of the local authorities, the mayor of St.Etienne en Devoluy, representatives from the Conseil General in Gap, and representatives from the company currently operating the ski station at Superdevoluy, to have a common solution that would serve both the needs of IRAM, and the needs of the community who wants to develop further the skiing resort and to start a small scientific/cultural activity in connection with the Observatory. The highest skiing areas are at about 2300 to 2400m, i.e. at the foot of the `falaise'. The future means of transport should therefore be capable to bring up large numbers of people to this altitude level. Transport to the level of the Plateau, which is a protected area because of its special flora and fauna, does not need to have the same capacity. Initially it will mostly be used by the IRAM staff, subcontractors, and occasional visitors. Later, when the scientific/cultural center will be ready, the number of visitors is, of course, expected to go up.
The best way in which all these interests can be integrated seems to be the construction of a new cable car system with small cabins (`télécabine') which would connect the ski station Superdevoluy with an area called `Sommarel' where several ski pistes are starting. The `funiculaire' would continue from there to the Observatory.
Such a hybrid solution will need the combined efforts of the CNRS/INSU, the local authorities (the Prefet, the Conseil General in Gap, the Mayor of St.Etienne), and the Conseil Regional of PACA (Provence, Alpes, Cote d'Azur) in Marseille. Together they will have to define the details of such a project, to secure its financing, and to solve all related administrative questions. Irrespective of which particular choice will be made for the future means of access to the Plateau de Bure, most of these institutions would be involved in the administrative process anyhow. Working together on a more ambitious project that corresponds to the interests of all partners, could therefore be an enormous advantage despite its increased complexity.
Where are we today? The Director General of the CNRS, Mme Berger, has recently written letters to all the potential partners, asking for the confirmation of their interest in a combined `télécabine-funiculaire' solution. In parallel, a close contact has been established between the technical division of the CNRS/INSU and of the Conseil General at Gap to discuss technical details on the basis of the existing studies, and to agree on a possible division of tasks. IRAM has been able to follow these discussions. As soon as all the potential partners will have confirmed their interest and the level of their participation in the financing, a final decision on the project will be taken.
For IRAM, the need to have a new, safe way of access to the Plateau de Bure, is, of course, of paramount importance. We are therefore particularly grateful that the CNRS is ready to take under its own responsibility the construction of the `funiculaire' and the improvement of the piste leading up to the Sommarel area. This will be needed to bring up the workers and the material necessary for building the tunnel and the inclined elevator. Hope is that most of this project can be finished before the end of 2002. By using a 4-wheel drive car in summer, and a ratrack in winter on an improved piste and by using the tunnel as soon as it is ready, the weather dependent problems of accessing the Plateau de Bure Observatory would already greatly be reduced.