Line D (Ligne D) is a line on the Lyon Metro which commenced operation between Gorge-deLoup and Grange-Blanche.
engineering
Description
- Line D (Ligne D) is a line on the Lyon Metro which commenced operation between Gorge-deLoup and Grange-Blanche. Based on commuters demand a new extension to the line is proposed.
At completion it will be 12.5 kilometres (7.8 mi) long and serving 15 stations, e.g. the longest
metro line in Lyon.
A new stretch of tunnel (extension Line D) is planned. This tunnel aims to connect Guilotiere and
Vieux Lyon Catedrale Saint Jean metro stations (Figure 1) and passes under the Rhône and the
Saône rivers. The preliminary design indicated that a circular tunnel having 6.5m diameter is
required and the tunnel is to be bored at variable depth typically ranging from 9-22m.
This tunnel project comprises the construction of a 1250m long twin tunnel with outer diameter of
6.5m, as a result of a contractor alterative proposal for the traditional but expensive method of
immersed tube tunnels. Tunneling is to be done using a slurry tunnel boring machine, which ensure
tunnel face pressure is maintained and thus minimizing settlement and ground losses deriving from
the tunneling process. The simplified geological profile of proposed tunnel alignment and critical
section in shown in Figure 2.
