Lines 2 and 3 of the Nice tramway system

Two tramlines including a 3.2km underground section on Line 2, with four stations.

The project team carried out 450 geotechnical surveys in and around the tunnel route to reduce any risks to above ground structures to an absolute minimum. Then a slurry tunnel-boring machine was used to excavate the tunnel while simultaneously installing a series of 40cm thick, 1.60m wide concrete segments to form the tunnel walls.

This tried-and-tested construction technique involved supplying a flow of naturally occurring clay (bentonite slurry) to the front of the cutter head to lock the soil in place during boring. The excavated soil was immediately replaced with ring segments of the concrete lining to minimise ground deformation.

Once work is completed, 2,500 trees were planted and 60% of the route was grassed. Construction work on this large-scale project was carried out with minimal disruption to the city’s inhabitants by keeping roads and car parks open.

The at-grade sections of the two tram lines are catenary-free thanks to a leading-edge ground-based static charging technology coupled with Citadis Ecopack supercapacitors. This technology means that the on board batteries can be recharged at stations from the ground in just 20 seconds.