Panama City, Panama — The tunnel boring machine (TBM excavating the underground section of Panama Metro Line 3 has successfully broken through at the Balboa reception shaft after completing its drive beneath the Panama Canal, delivering one of the most technically demanding tunnelling achievements ever undertaken in Central America.
The breakthrough follows the completion of the TBM’s drive beneath the Canal’s active navigation channel — the first time a mechanised tunnelling operation has passed below this globally critical waterway.
A Tunnel Beneath a Global Trade Artery
The underground section forms part of Line 3 of the Panama Metro, a 25 km rapid transit corridor linking Panama City with the fast-growing western suburbs of Arraiján and La Chorrera. The tunnel itself extends for approximately 4.5 km, connecting the Farfán launch shaft on the west bank of the Canal with the Balboa and Albrook areas on the east.
The machine, a large-diameter Mixshield TBM supplied by Herrenknecht, was specifically engineered to operate under extreme conditions. With a cutterhead diameter of approximately 13.5 m, the TBM was designed to manage highly variable geology and groundwater pressures of up to 7 bar at depths approaching 60 m below sea level.
Challenging Ground and High Water Pressures
Since launching from Farfán in September 2024, the TBM has excavated more than 3 km of tunnel, installing over 1,500 precast concrete lining rings and removing close to 800,000 m³ of excavated material. Ground conditions along the alignment included mixed sedimentary and volcanic formations, requiring continuous adjustment of face pressure, excavation parameters and conditioning strategies.
Tunnelling operations were carried out around the clock, with strict monitoring protocols in place to ensure no impact on Canal operations above. The successful passage beneath the navigation channel demonstrates the level of precision now achievable in large-diameter mechanised tunnelling under sensitive infrastructure.
Breakthrough at Balboa and Next Steps
The TBM’s arrival at the Balboa shaft marks the completion of the most complex section of the drive. The machine will now undergo a planned maintenance and inspection period lasting several weeks, including cutterhead checks, mechanical servicing and system upgrades, before resuming excavation toward the Albrook extraction shaft.
Once tunnelling resumes, the remaining drive will extend for approximately 1.5 km, after which the TBM will be dismantled and removed.
Transforming Cross-Canal Mobility
Metro Line 3 is expected to significantly reduce travel times for commuters crossing the Canal, offering a high-capacity alternative to the heavily congested bridge crossings currently in use. Once operational, the line is forecast to carry more than 500,000 passengers per day and play a central role in Panama’s long-term urban mobility strategy.
From an industry perspective, the successful Canal crossing highlights the growing capability of modern TBMs to operate safely and efficiently beneath critical infrastructure, even under high pressures and complex ground conditions.
With tunnelling works progressing and station, viaduct and systems construction advancing along the alignment, Panama Metro Line 3 continues to move steadily toward completion, setting a new benchmark for underground construction in the region.
Main Public Tender for Line 3 (Includes Tunnel Works)
The core public procurement for Panama Metro Line 3 was launched as Public Tender No. 2017-2-80-0-08-LV-001402, covering the design, engineering, construction and commissioning of the entire Line 3 system (including the underground tunnel segments). This tender was awarded in 2020 to the HPH Joint Venture consortium (Hyundai Engineering & Construction, Posco, and Hyundai Engineering), which serves as the main contractor for the project.
Scope: ~25 km metro line from Albrook to Ciudad del Futuro (elevated, viaduct and underground sections). Includes: Tunnel design/construction under the Panama Canal integrated into the main contract. Outcome: Awarded and underway; HPH JV leads project delivery.
Early Tunnel Design Tender (Pre-2021)
During the early technical planning stages, a separate tender process for preliminary tunnel design was initiated in 2021 for the Panama Metro Line 3 tunnel under the Canal. Four consortia bid for this specialized design work, and a consortium (Tunel de las Américas — Typsa and Louis Berger) was rated highest, but the contract was ultimately not formalised due to compliance issues. The design responsibility was later rolled into the main Line 3 contract held by HPH JV.
TBM Operation Contract
Separately from the public authority’s tender, a contractual agreement was signed between HPH Joint Venture (the main contractor) and China Railway Tunnel Group (CRTG) for the tunnel boring machine operation. This is a contractor-to-contractor arrangement, meaning Metro de Panamá did not issue a separate public tender for TBM operations — the main contractor subcontracted that work in line with its scope. 07/26.
