As an indication of the end of the excavation process of a first section of the Line 17 tunnel of Grand Paris Express, from the Verdun structure located at Le Bourget, the Dorine tunnel boring machine attained the Rolland structure in summer 2021. At the moment this machine returned to its starting point and is going to commence a second drive in order to construct the 2nd section of the connecting tunnel for lines 16 and 17, which is still in the direction of the Rolland structure.
The reason for the possibility of the duplication of tunnels 16 and 17 at Le Bourget, where lines 16 and 17 separate to continue their respective paths to the East and to the North, is two particular works: The Verdun work and the Rolland work. Starting shaft for the tunnel boring machines responsible for boring these tunnels is the first intended work, while the second one is the arrival point for the tunnel boring machines digging line 17 specifically. Hence among these 2 particular works the playground of the Dorine tunnel boring machine is found.
On 30 August 2021, following a 6 months excavation, 20m beneath the Bourgetine basement, and laying the tunnel lining, the Dorine tunnel boring machine completed its drive. Nearly 3 and a half months of dismantling and disassembly followed the imposing machine, just over 1000 tons and 120 meters long. The spare parts were gradually extracted from the structure, stored on the site before returning to the site where everything had started a few months earlier, the Verdun structure site.
Firstly, extracted from the well and evacuated from the site, the cutting wheel the drill head of the machine due to its diameter of almost 7 meters benefited from a specific evacuation system. During its transfer, on the night of October 27 to 28, it was carefully installed on a truck before crossing the streets of Le Bourget in an exceptional convoy, that is to say, at low speed and under police escort, to ensure the safety of motorists and residents.