Panama finishes a metro tunnel 65 meters beneath the Panama Canal

The machine, nicknamed "Panamá," started from Farfán on the canal's west bank in late 2024, ENR reported. More than 250 workers on round-the-clock shifts removed nearly 700,000 cubic meters of rock and soil and installed 2,295 concrete rings of nine segments each. Hyundai Engineering & Construction leads HPH, the joint venture that holds the Line 3 contract, with POSCO E&C and Hyundai Engineering as partners. HPH hired China Railway Tunnel Group to run the machine.

A tunnel was not the first plan. Line 3 was supposed to cross on the cable-stayed Fourth Bridge until the government split the two projects in 2020. The Panama Canal Authority then asked for 7 meters of clearance for future deepening and cover of one and a half tunnel diameters, which put the bore about 9 meters deeper than designed. At that depth the machine faced 6 to 6.5 bar of water pressure; Herrenknecht says it designed the machine for up to 7 bar. Its cutterhead let crews change tools at atmospheric pressure instead of working in compressed air.

Agustin Arias, who ran projects at Panama Metro at the time, chose one large bore over twin tubes to avoid hand-mined cross passages under the canal. To meet NFPA 130 egress rules, the team placed a prefabricated escape gallery in the tunnel floor and keeps it under positive pressure to hold out smoke.

The breakthrough slipped from late September after a worker died on Sept. 21, the project's second fatality in about a month, and again after a magnitude 7.7 earthquake on Oct. 9, ENR reported. Work now moves to the guideway, stations and systems, with about 4,000 workers on the project. Panama Metro plans to carry its first riders in 2028.