Tunnelling Starts at Pajares with Herrenknecht TBMJose Luis Rodriguez Zapatero, the Spanish PM, and Magdalena Álvarez, the minister of public works, celebrated on 13th July, 2005 the launch of the first TBM at Pajares, on the Leon-Asturias high speed line. The first machine to start is a Herrenknecht, acquired to build contract 1 which starts from La Pola de Gordon in Leon province, where is located the south portal of the tunnels. The Pajares tunnels consist of two parallel tubes, each 24.7 km in length. They are the most challenging project of the Pajares Pass rail bypass. The Pajares bypass is 49.7 km long altogether and encompasses, in addition to the construction of the tunnels, north and south sections to La Robla and Pola de Lena on each side of the tunnels. These sections will also include tunnels. To ensure the highest level of security, the tunnels will be cross connected every 400 m, which will facilitate maintenance and evacuation in case of emergency. One of each three crosscuts between both tubes will be executed simultaneously with the excavation of the main tunnels. Five TBMs will be working to drive the Pajares tunnels (2 Herrenknecht, 2 Wirth-NFM Technologies and 1 Mitsubishi-Duro Felguera). The project represents a major engineering challenge, which magnitude is similar to the recently completed Guadarrama tunnels. The Pajares tunnels will be the sixth longest in Europe and the seventh longest in the world. The works have been divided into four contracts.Contract 1 Pola de Gordon-Folledo in Leon province includes the construction of two tunnels (east and west) between Pola de Gordon, where is located the south portal, and Folledo district. The tunnels will be driven by a JV of FCC and Necso. To dig the tunnels within this contract, two different construction methods will be used. The first 7.9 kilometres from Pola de Gordon will be drilled with two TBMs (the Herrenknecht that just started and a Wirth-NFM Technologies that is nearly assembled at the start site, awaiting to undergo the test phase), and the remaining 2.5 km to be built using conventional methods. The length of the Herrenknecht hard rock single shield TBM S-287 is 225 m with its back-up. Its weight is 2,109 tons altogether (1,209 tons for the cutter head and 900 tons for the back-up). The diameter of the cutting head is 9,900 mm. The installed total power is 8,000 kVA. The installed total power of the main drive is 4,900 kW (14 x 350 kW). The nominal thrust is 115,000 kN and the maximum thrust 180,000 kN. The machine is equipped with 24 cylinders. The cutter head's nominal torque is 19,960 kNm. Visit www.herrenknecht.comIn addition to both tubes, a 2 km access adit is being constructed from the surface, of which already 1,490 m has been excavated by conventional means. The entrance of this access tunnel is situated between Buiza and Folledo. At the junction between this adit and the main tunnels, a cavern will be build to allow for the disassembly of the two TBMs which will drive up to this point from the portal in Pola de Gordon. The segment production line for this contract has already fabricated 1,050 rings (7 segments per ring), which are currently stored in the supply area installed next to the plant.As part of contract 2 Folledo-Viadangos (Leon province), known as the central section, two 3.9 km tunnels and a 5.5 km access adit leading to these tunnels will be constructed. The builders of this second contract are Dragados and Obras Subterraneas. To date, the first 15 m of the access adit's portal has been excavated by conventional means and the rolling slab and cradle for supporting the TBM in the launch area have been built, as well as the set of tracks, warehouse and workshop buildings. The gallery, which commences in Buiza (near Folledo in Leon province) until meeting with the main tunnels, is going to be excavated with the same TBM as the one which will afterwards bore the main tubes. On completion of the first tube, this TBM will be disassembled and reassembled again to pursue the tunnelling of the second tube. The disassembly / reassembly tasks will take place in a cavern constructed at the junction between the access adit and the main tunnels. In this second contract, in addition to the cavern, a 400 m-long preferential stop area and two reversible working areas for railway traffic will be constructed between the main tubes. The preferential stop area will serve so that in the event of a failure, power cut, etc., trains can stop at this point, since this is where will be built a network of cross connected galleries also linked with the access tunnel, thereby enabling the easy evacuation of passengers out of the tunnel, in case of emergency. On the other hand, the reversible working areas will make possible to direct trains from a tunnel to its twin. The TBM that will construct contract 2 is a Herrenknecht. It is under assembly, with the first three back-up trailers already mounted. The TBM assembly could be finalised at the end of August and tunnelling would begin in the first half of September. The segment plant for this contract, located in Leon province's La Robla municipality, is already operational and 50 rings have been produced at this stage (7 segments per ring). They are currently stored in the supply area installed near the plant.Contract 3 Viadangos-Telledo includes the driveage of the east tunnel section between Viadangos (Leon province), where is the limit between contracts 2 and 3, and Telledo (Asturias), where is the north portal (Asturian side). This section entails approximately a tunnel length of 10.3 km. The contractors are a JV set up by Ferrovial Agroman, Sacyr and Cavosa. Two different tunnelling methods will be used to build this contract. The first 40 metres from the portal will be bored by conventional means while the remaining length, until the breakthrough point with the final tunnel stretch within contract 2 in Viadangos (Leon province), will be driven by a TBM. Contract 3 also involves the preparation, development and management of La Cortina dump site. This is where will be stored the excavated material resulting from the excavation of this tube and the parallel contract 4. At the moment, preparatory works are under way to build the access trail to assemble a 1,352 m conveyor belt that will take directly the excavated rock from the tunnels to La Cortina dump site. Also, the excavation and reinforcement works of the slope where will be dug the portals are under way. The segment production plant is being built in the vicinity of Sotiello and the segment storage field is being prepared to install the supply platform. The Wirth-NFM Technologies TBM for this contract is in fabrication and is scheduled to arrive at the site after the summer. It will be transferred in parts from the factory in Le Creusot, France.Lastly, the 10.3 km contract 4 Viadangos-Telledo has been awarded by a JV formed by Copcisa, Constructora Hispanica, Brues y Fernandez Construcciones and Azvi. These contractors will build the west tunnel section between Viadangos (Leon province), at the junction with contract 2, and Telledo (Asturias), where is the north portal (Asturian side). This contract also includes the tunnelling of the cross passages each 400 m, between this tube and the parallel twin bore, which is part of contract 3. At this stage, the only activities concern the preparation of the worksite since tunnelling of the portal will not begin until the ongoing access platform to the portal (part of contract 3) is finished. The segment production plant and the segment storage area are under construction, as well as the offices and other facilities. The segment plant for this contract is located in Sotiello, next to the plant of contract 3. It will be possible to begin the production of the segments at the end of August. The arrival of the first parts of the Mitsubishi-Duro Felguera TBM for this contract is programmed for the last quarter of 2005. The machine will be transferred from Duro Felguera's factory in Asturias. Tunnelling could commence in the first quarter of 2006, once the assembly and subsequent testing of the machine at the site are finished.The Pajares tunnels are the most technically complex project for the high speed link between the meseta, or Spain's central plateau, and the Galician and Cantabrian regions. Furthermore, the EUR1.4 billion investment required for building these tunnels is one of the highest ever made in the construction of rail tunnels and viaducts in Spain. The tunnels will safeguard the entire mountainous massif at Pajares Pass, a natural barrier that separates Galicia and Asturias with the central plateau. They will permit to travel at high speed between Madrid or the main cities in Castilla and Leon and the main cities in Galicia and Asturias. When the construction is completed in the second half of 2009, the tunnels will reduce by 34 km the distance by rail between Leon and Gijon, which represents a gain of 40%. The Pajares bypass will reduce by one hour and five minutes the journey time between the two cities, from 2.5 hours to just one hour and 25 minutes. Travelling through the tunnels at high speed will take about 15 minutes. Click es/55. 30/05.