The project has just exceeded 50% of the total progress and has recently passed the 75% mark for special works. These important milestones should not obscure the significant technical challenges that lie ahead.
The Vert de Maisons station has been the site of offset drilling and freezing since July. The first freezing drilling phase at level-4 has been completed. The drilling phase will continue until May 2020 with the sub-horizontal drilling under pressure over a distance of 70m for offsetting and freezing.
Compensation grouting will start with an initial phase starting in mid-October 2020 and active freezing should be effective in November 2020.
Two of the last three ancillary works have been undergoing excavation since the start of September: 1301 and 1501, at Alfortville and Vitry respectively. These two circular shafts, the deepest of which (1501) is formed by diaphragm walls nearly 70m high, are made with a Hydrofraise® with interlocking joints. The wall activity will end in May 2020 however, with the last structure, 1201, in Créteil.
On the civil engineering front: the station of Créteil Echat was released for T2B package, with its tunnel boring machine being installed there, the stations Vitry Center and Les Ardoines have reached the bottom of their excavations and the bottom slabs were poured, and at Vert de Maisons, cast-in-situ earthworks have reached level -6, which is where our drilling takes place.
The Aby tunnel boring machine (TBM4) set off on 17 June from the well of the Arrighi wasteland towards Les Ardoines, that it has just reached. The Marina tunnel boring machine (TBM2) has recently been named and will start its race in the next few days.