The second Herrenknecht EPBM to be used on Portugal’s new Porto Light Rail System is due to start excavation this summer on the project’s southerly 2.8km long drive from Salgueiro Station to Trinidade Station.
The project’s first Herrenknecht EPBM is currently boring the 2.3km long drive from Campanha Station towards Trinidade where some difficult ground conditions have been experienced in the past.
The geology along the alignment consists of continually alternating bands of fresh and weathered granite (residual soils) which hindered the excavation of the first TBM. The TBM was required to work in closed mode in mixed face, a situation common to this project. The tricky geology has lead to the decision to introduce another TBM to the project in a bid to increase production rates.
The second machine has been purchased by the Transmetro JV, which is constructing the US$90.6M civil works contract for the client, Metro do Porto. The JV consists of Portugal’s Soares da Costa y Somague and Impregilo of Italy.
The new Porto Light Rail System consists of a network of about 70km of lines, involving the conversion and upgrading of 50km of existing surface tracks and the construction of 20km of new lines, 7km of which are underground between Campanha – Trinidade and Salgueiros – Aliados. The underground section is composed of segmentally lined (6+1) bored tunnels with 7.8m i.d. and a 30cm lining thickness. The tunnel runs down to a maximum depth of 32m.
