It’s like a worm. But huge: a machine 120 meters long and 12 meters in diameter. He pierces the subsoil of Barcelona and leaves a built tunnel because he places concrete voussoirs that form a tube. This week he is working 43 meters underground. It is the German-made tunnel boring machine that was put back into operation last summer after a ten-year hiatus due to lack of funds. The access shaft is very close to Camp Nou and has advanced almost a thousand meters since work resumed. It is 500 from the future Sarrià station. It advances between six and up to 25 meters per day, depending on whether it is working underground against slate, granite, sandstone or conglomerates.
The tunnel boring machine completes the remaining stretch to connect the two working sections of the L9 subway, which curves on one side between Badalona and Santa Coloma; and the airport and free zone on the other side, running through the upper part of the city. There is only 4.2 kilometers of a line that will be paid for by the Generalitat and will have a total of 48, 50 stations and 17 transfer points. All, at a cost of 6,000 million, 864 in this final push. With the 10 remaining stops between Collblanc and Sagrera, this line, whose route runs parallel to the Ronda de Dalt, will attract 90 million passengers a year as these are neighborhoods that now have no metro, says David Prat, Director General of Mobility Department of Territory infrastructures. The calendar envisages commissioning (not all stations at the same time) from 2027.
Interior of the L9 tunnel boring machine of the Barcelona Metro, a 120 meter long and 2,300 tonne machine, with the rails of the wagons that transport personnel and material from a shaft with exit to the outside MASSIMILIANO MINOCRI
The L9 tunnel boring machine that this newspaper has visited will not be the only one to carve its way underground in Barcelona in the next few years. The government also has on the table the project to extend the L8 of the Ferrocarrils de la Generalitat to connect the Baix Llobregat and Anoia line to the Vallès line, with an investment of 430 million. With only four kilometers and two stops (Hospital Clinic and Francesc Macià) between Plaça de Espanya and Gràcia, the two lines (99 kilometers and 51 kilometers) will be connected. In total, they add up to 84 million passengers a year, and they are projected to earn 14 million more. For example, students from Baix Llobregat studying at the Universities of Vallès. The work, which is not construction of the tunnel itself but previous work, will begin before the end of the year and the calendar points to 2028-2029 to complete the link.
Graphic of the tunnel boring machine building the L9, with the cutting wheel, the earth chamber, the steel shield protecting the head, as well as the segmental arches already placed and the belt transporting the earth to the outside. / GENERALITIES OF CATALONIA
At the L9 works near the Camp Nou, to get to the TBM, one must first descend by industrial elevator to a shaft (a cylinder 31 meters in diameter and 39 meters deep) that serves as access for the operators, but also to the materials; and take a trolley, which takes about twenty minutes to get to where the giant machine is digging. Down in the shaft you can see the belt with the excavated material coming from the tunnel boring machine, an infrastructure with its own smaller exit tunnel that ends a few meters further. Shoes with reinforced toes, a bright yellow helmet and vest are essential.
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The cutting wheel of the tunnel boring machine that bores holes in the subsoil of Barcelona and in its central section builds the future L9 tunnel. It measures 12 meters in diameter and the stone that can be seen on the metal structure is granite: MASSIMILIANO MINOCRI
The tunnel boring machine is a monster weighing 2,300 tons. It’s impossible to see it in its entirety because it’s like a giant metallic worm stuck underground. But it’s easy to get used to the idea of traveling 120 meters with tubes, platforms, generators, stairs and metal walkways, huge tools, cable reels, a big yellow pipe bringing air from the surface… all this, until you reach the head. The engine room of the machine: the command center, which looks like a ship (with screens showing what the machines are recording and endless tables with the dig parameters … and a coffee machine, because there is staff here 24 hours a day). day) ; the large hydraulic crane that places the keystones from a bridge with the help of two people, the earth room and the impressive cutting wheel that spins and scrapes the wall.
The process is as follows, explains Laura Carrasco, a Territorial Department technician: The wheel rotates at a pressure calculated based on the material it is exposed to, dumping the material into the earthen chamber (which is emptied onto the conveyor belt ) and every time he advances 1.8 meters he stops to place the Ring of Voussoirs. An impressive manoeuvre, as each arch consists of seven 40 centimeter thick concrete voussoirs and pieces of neoprene to make them very waterproof. There are seven different pieces from each other, so depending on placement, the shape of the tunnel is straight, going up, down, or left and right. Once each arch is closed, grout is injected to strengthen it.
Two operators prepare the advance parameters for the tunnel boring machine on the L9 in Barcelona in the earth chamber behind the cutting wheel. A space where only divers enter during high-pressure work.MASSIMILIANO MINOCRI
Sílvia Rodríguez, project manager of the tunnel, adds that a total of 200 people work inside: the tunnel boring machine works 24 hours a day, every day of the week in three operator shifts. There are engineers, geologists, the pilot of the tunnel boring machine, machine operators, technicians for very specific machines, electricians, fitters (those who place the voussoirs), managers … and sometimes during the excavation, divers too, if they work under a lot of pressure (exerted by the wall being drilled) and the weight must be balanced with the power of the machine.
The L9 is built with a system of the same name developed in Barcelona: inside the same tunnel, separated by a plate, the meters circulate on two levels in each of the directions. There is a train and platforms on each floor. And in this system, the stations are not caissons built at a shallow depth in relation to the road (like the L1, L3, L4 or L5 lines). On L9, since the meters are so deep, the stations are shafts that go down as much as 70 meters where the tunnel and platforms are located, which are reached by heavy-duty elevators.
Exterior of the tunnel boring machine shaft on L9 of the Barcelona Metro near Camp Nou. The concrete pieces are the voussoirs with which the tunnel is built: each arch has seven pieces, all different but depending on how they are placed, they mark the direction of the MASSIMILIANO MINOCRI tunnel
The Government and City Council confront each other over the impact of the L8 on 140 trees in Joan Miró Park
The future construction works of the tunnel to extend the L8 of the Ferrocarrils de la Generalitat have raised alarm in the area around the Joan Miró Park and provoked a confrontation between the government and the city council. The 2014 project, positively evaluated by Parcs i Jardins, plans to use part of the park to create a commercial site, which would mean cutting down almost 140 trees. The Generalitat defends that it is very difficult to reduce the impact of the works on the park, while the City Council asks that deforestation be avoided and that an alternative be found. One of the fountains will be installed on Gran Via, at Carrer de Llançà, where traffic needs to be reduced. The demolition of the site will also bring with it a large amount of truck traffic, estimated at between 100 and 300 per day depending on the progress of the TBM.
The machine room from which the tunnel boring machine for the L9 of the Barcelona Metro is controlled and operated. The screens show the excavation parameters.MASSIMILIANO MINOCRI
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