• A refurbished tunnel boring machine adapted to the needs of the project was used to construct the tunnel, which is more than 13.3 kilometers long

ACCIONA and its partner, Sacyr, have completed the excavation of the Mularroya dam transfer tunnel (Zaragoza), having successfully achieved the final breakthrough.

ACCIONA’s UTE has carried out this project, which includes the design and construction of the Mularroya dam, as well as the construction of a national road bypass and the diversion pipeline, including the construction of more than 13.3 kilometers of a tunnel with a diameter of almost three meters.

Construction of the tunnel began in 2020 and, by the end of 2022, more than 8,200 meters had been excavated, to reach the tunnel’s halfway point. From then on, work continued on an open-air route and finally, at the beginning of 2023, the excavation of the last 5,000 meters of tunnel began.

For the excavation, ACCIONA refurbished one of its double-shield TBMs and adapted it to the needs of this project, which, required a single-shield rock TBM due to the complex geology of the route. In addition, due to the long length and limited internal diameter of the tunnel, a conveyor belt has been used for the evacuation of earth, minimizing the use of locomotives, which are also electric. This has reduced to "0" the emissions of polluting gases generated by the transport inside the tunnel during its execution.