For months, Gala, an earth pressure balance (EPB) tunneler with an excavation diameter of 10.6 meters, has been digging away under one of Europe’s largest airports. The goal is to improve its connection to the city.

Gala’s tireless work has helped complete the 3,385 meters of the new underground rail connection at Barcelona airport. Above its immense serrated head sprawled the corridors of Terminal 2 and the main runway of the airport. The rest of the construction on this project, some 4,495 meters in all, was done above ground, in full daylight.

When it is finished, the two terminals of El Prat-Josep Tarradellas will connect with Barcelona’s light rail network for the first time. The first stop will be at the T2 interchange, which is closest to the city. The train will then go back underground, running under the airfield to the intermodal station at Terminal 1. This new connection will serve the 50 million passengers who visit El Prat each year.