Ground investigations will be completed this month for the planned 4.2km long extension on Paris metro’s Line 4, France. The test pit being used was started in July 2002 by RATP, the French public transport department, and results will be available later this summer.

Extensive ground investigations have been carried out to test and approve various geophysical investigation methods in the demanding ground conditions, the area crossed by the extension is undermined by ancient stone quarries.

The Line 4 will extend south from Porte d’Orléans to eventually serve three extra stations: Mairie de Montrouge, Verdun-Sud and Bagneux. Initially, however, plans are only in place to extend as far as Mairie de Montrouge, the most expensive and complicated station.

This 1.5km of tunnel will cost about US$350M, and invitations to tender for its construction are scheduled to go out in the summer 2004. Tunnel construction could begin before the end of 2004.