Third TBM launched on Pajares scheme17 November 2005
A second Herrenknecht TBM was launched on 22 September on the Pajares tunnels, part of the Leon-Asturias high-speed railway line in Spain.
The scheme consists of two parallel tubes, each 24.7km long, part of the 49.7km long Pajares Pass rail bypass. The work has been packaged into four contracts.
The S-281 Herrenknecht 10.16m diameter double shield hard rock TBM starts work on the US$484M contract 2, which is the central section of the scheme, with a 5.5km long access tunnel, replacing two 600m deep shafts as suggested by contractors Dragados and Obras Subterraneas to client ADIF. The TBM will then be used for twin 4.5km long 8.5m id running tunnels from the southern Leon side through geology expected to comprise of sandstone and slate. After completing the first tube, the TBM will be disassembled and transported back to the start point to bore the second tube.
It is the third TBM to get underway on the project following the first TBM launch on 13 July, a S-287 Herrenknecht 9.9m diameter hard rock single shield for contract 1 and a 9.93m diameter NFM Technologies hard rock single shield TBM launched in mid-September, also for contract 1.
The contractor for this package is a jv of FCC and Necso. The jv opted for a mixture of excavation methods with 7.9km of parallel tunnel being bored by the aforementioned TBMs and the remaining 2.5km being built by conventional methods, as is the 2km long access adit. The TBMs are both driving from the south portal.
Contract 3 and 4 feature drives from the northern side of the tunnel scheme. Contract 3 was awarded to a jv of Ferrovial Agroman, Sacyr and Cavosa. The bulk of this 10.3km length will be bored using an NFM TBM, due to be delivered in mid-November. Contract 4, which also consists of 10.3km of tunnel, will be bored by the jv of Copcisa, Constructora Hispanica, Brues y Fernandez Construcciones and Azvi using a Mitsubishi-Duro Felguera TBM that is scheduled to start arriving on-site from early next year.