Mexico City Metro Line 12 Extension (Mixcoac–Observatorio)

Alignment

The extension continues Line 12 (Tláhuac–Mixcoac, 20 stations), which reopened in full in January 2024 after the May 2021 overpass collapse at Olivos station, west and north from Mixcoac in a 4.6 km tunnel about 30 m below ground, through the Álvaro Obregón borough and into Miguel Hidalgo. It adds three stations: Valentín Campa, at Eje 5 and Alta Tensión; Álvaro Obregón, near the borough government building; and a new terminal at Observatorio, which connects with Line 1, the Mexico City–Toluca interurban train, and the Observatorio bus terminal and transfer hub. A depot for 12 trains is planned at Observatorio. With the extension, Line 12 would be 28.3 km long, the longest in the system. Officials estimate it will serve about 220,000 nearby residents and add 63,000 new Metro users.

The route passes under old mines that were later filled with debris and rubbish. Crews had to inject soil-cement to firm up the ground, use double concrete linings and waterproofing, and limit vibration under the homes above. In one stretch of about 30 m, excavation slowed to a meter or so a month. The tunnel and the shells of the two intermediate stations are built; the Observatorio terminal, the depot, track, and electrical and electromechanical systems (ventilation, control, lighting, and communications) remain.

The work has been paid for with federal money. Mexico City’s public works department (Sobse) carried it out at first; since Claudia Sheinbaum became president, ATTRAPI, the federal passenger rail agency, has led it, with remaining funds held in Banobras’ national infrastructure fund (Fonadin). The Metro (STC) is responsible for buying 12 new trains to bring the line’s fleet to 42.

Updates

2026-09 — Sheinbaum says 2027 budget will fund completion

President Sheinbaum said the draft 2027 federal budget includes money to finish the extension, which began under Enrique Peña Nieto and missed completion targets of December 2018 and December 2021. She blamed the delays mainly on the soft, debris-filled ground in Álvaro Obregón.

2026-07 — Stations about 30% built; service set for 2029

During a site visit, ATTRAPI head Andrés Lajous said Valentín Campa station was 28% complete and Álvaro Obregón 30%. The contract for the Observatorio terminal was still to be tendered. He said works should finish in 2028, with the new stations opening in 2029. The remaining work is funded with MX$11B from Fonadin.

2026-05 — Remaining works and costs outlined

Animal Político reported that the original MX$8B estimate had been followed by MX$9B in multi-year funding approved for the pending works. Still to be built were the Observatorio station, the depot, and the electromechanical systems, and a tender for the station works was being prepared.

2026-04 — Tunnel excavation completed

On April 30, 2026, the federal transport ministry (SICT) announced that excavation of the connecting tunnel was finished, after transport secretary Jesús Esteva and Lajous toured it on April 29. The next stages are station construction, track laying, and electrical and electromechanical installation.

2025-10 — Last 30 m of tunnel advancing slowly

SICT head Jesús Esteva said progress on the tunnel had been minimal, averaging about 1.5 m every four weeks, because of the need to protect buildings above the works. About 30 m remained between the Rosa Roja shaft and Valentín Campa station.

2016 — Extension works under way

Work on the extension was under way in 2016, paid for by the federal government and carried out by the Mexico City government. Officials said that year it would be finished by September 2017; later targets included December 2018 and December 2021. Sources differ on the exact start date, citing dates from 2015 to 2017.