Mumbai Metro Line 7A Achieves Final Breakthrough In Upline Tunnel Connecting Andheri (East) To CSMIA

Mumbai: The under-construction Mumbai Metro Line 7A on Monday, 14th July 2025, marked a significant milestone with the successful breakthrough of the upline tunnel, the second and final tunnel of the corridor connecting Andheri (East) to Chhatrapati Shivaji Maharaj International Airport.

The initial drive of the TBM named Dhruv started on 4th November 2023. The length of this upline tunnel is about 1.65 km, which requires the installation of 1178 rings of 1.4m length for the tunnel lining. The finished tunnel diameter is 5.6 m, and precast ring segments consisting of 6 parts are used as the tunnel liner. This breakthrough has been achieved after overcoming the various obstacles like crossing over Metro Line 3, below the ramp of the Sahar Elevated road, a major underground Sewer line, and a major underground water line.

Presently, 61% progress has been achieved for the complete alignment. In April this year, TBM Disha made a breakthrough first on Metro Line 7A.

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About Metro Line 7A

The Metro Line 7A (Andheri (East) to CSMI Airport) is an extension of the presently operational Red Line ML7 (Andheri (E) to Dahisar (E). This alignment is partially elevated and underground and runs parallel to the WEH & Sahar elevated road. It consists of two stations, an elevated Metro station named Airport Colony and an underground station named Chhatrapati Shivaji Maharaj International Airport.

The alignment enters underground just before the Vehicular Underpass of Sahar elevated road, Vile Parle (E), and reaches the underground Metro Station at CSMI Airport, parallel to terminal T2 and ML3 (Coloba-Bandra-Seepz) CSMIA Metro station. The overall Metro 7A is 3.4 km in length.

Major Obstacles Overcome by MMRDA for the Metro 7A, which follows Airport Authority of India (AAI) transferred the required land for ML7A projects on 11 October 2021. About 200 hutments were resettled and rehabilitated in Bamanvada, Valmikinagar, and Vile Parle.

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An underground sewer line of 1800mm diameter infringing the tunnel alignment was diverted using the Micro tunnelling method and commissioned on 30th January, 2023, in coordination with BMC and the Post and Telegraph department. Also, Diversion of various utilities like 2400mm diameter main, gas pipelines, Sewer line, Storm water drains, etc., is carried out.

MMRDA is implementing a 337 km Metro network across the Mumbai Metropolitan Region (MMR). Out of this, presently Metro Lines 1, 2A, and 7 have been made operational and dedicated to the service of Mumbaikars. While Mumbai Metro Rail Corporation(MMRC) commissioned the city's first underground metro line 3 between Aarey to Worli. Further, the works of Metro Line 2B, 4, 5, 6, 7A, 9, and 12 are in progress and in full swing, some of which will be partially opened this year-end or early next year.

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Project Features

• Length: 3.4 km (Elevated - 0.94 km, Underground - 2.503 km)

• Stations: 02 Nos. (1 - Elevated (Airport Colony), 1- Underground (CSMIA))

• Elevated Viaduct: 0.57 km

• Ramp: 0.309km

• Twin tunnel of 2.035km length with a diameter of 6.35m.

• TBM type: Dual-mode hard rock TBM.