The Cuijiadian Parking Lot for Metro Line 7 is beginning to take shape.
Spanning an area equivalent to 13 football fields, this massive project involves excavating over 2 million cubic meters of earth and rock, pouring 420,000 cubic meters of concrete, and using more than 96,000 tons of steel reinforcement bars. This is Asia’s largest underground double-decker subway parking lot currently under construction — the “Subway Home” Chengdu Metro Cuijiadian Parking Lot. Excavation and other underground groundwork have been completed, and the project has fully entered the main structural construction phase, with completion expected by August this year.
A Giant Structure Covering 13 Football Fields, Capable of Housing Over 70 Trains
Visiting the Cuijiadian parking lot construction site yesterday, I was amazed by the scale of operations. Sixteen tower cranes stood tall like steel trees, while over 200 machines worked across the site. Vehicles moved constantly, and cranes lifted materials in a seamless rhythm. According to an on-site construction official, more than 1,200 workers from various specialties are currently involved in the project.
The Chengdu Metro Construction Branch explains that the Cuijiadian Parking Lot is a key facility on Line 7, responsible for parking and inspecting all trains operating on the line. It also handles bi-weekly and tri-monthly maintenance inspections. The parking lot features a two-story underground reinforced concrete structure divided into four sections: Area A (connecting line), Area B (throat area), Area C (train inspection and washing garage), and Area D (operating warehouse).
The title of Asia’s largest subway parking lot comes from its vast size — a total construction area of 182,900 square meters, with a foundation pit measuring 200 meters wide and 600 meters long, averaging nearly 20 meters deep. The project involves over 2 million cubic meters of excavation, around 6,000 pile foundations, 420,000 cubic meters of concrete, and upwards of 96,000 tons of steel reinforcement. “Its footprint matches the size of 13 football fields,” said Anran, Deputy Director of the Engineering Department 2 at Chengdu Metro Construction Branch.
Public data shows that once operational, the parking lot will accommodate more than 70 train sets. As part of Line 7 — a circular metro route with 31 stations — the lot plays a vital role in vehicle management and scheduling. The site near Huaishudian Road was chosen because of its large available space and convenient connection to the main line.
Addressing Complex Geology: No Blasting Allowed, Only Careful Rock Chiseling
Anran noted that the project sits on expansive soil typical of Chengdu’s eastern gate area. This soil is unstable, has poor plasticity, poses high safety risks, and makes construction challenging. The work must also endure flood season, adding to the safety concerns for flood control and deep foundation pit excavation.
To boost efficiency, the Cuijiadian parking lot construction utilizes BIM technology for structural modeling, quantity calculation, and pipeline collision detection. This enables visualization and virtualization of construction processes, optimizing the allocation of personnel, materials, and machinery, and significantly improving calculation accuracy and site management speed.
Connecting to Metro Line 7’s main line, the parking lot’s entrance and exit lines form a figure-eight shape linking Cuijiadian Station and Huaishudian Station, ending at the parking lot. The total length of this section is 1,259 meters, with a maximum depth of 20.8 meters.
The underground excavation section for these entrance and exit lines runs close to the shield tunnels of Line 7 between Cuijiadian Station, Shuangdian Road Station, and Huaishudian Station. Due to this close parallel and intersecting layout, construction safety requires that the underground excavation tunnel be built first, followed by the shield tunnel. Unlike other sections, these cannot be built simultaneously.
Geological conditions here are complex. Surrounding rocks in the excavation section consist of either high-strength moderately weathered mudstone or weak, unstable strata, posing construction challenges. Near the Cuijiadian parking lot, the tunnels are deeply buried in high-strength, moderately weathered mudstone. Since the area is urban, blasting is prohibited, so excavators equipped with crushing heads carefully chisel the rock piece by piece. The construction official confirmed this method. The underground excavation for the parking lot’s entrance and exit lines is expected to finish by July, paving the way for shield tunneling and track laying.
Currently, the Cuijiadian parking lot construction is progressing smoothly, fully engaged in main structural work. Some sections have already topped out. Over 80% of civil engineering tasks are complete, with the main structure expected to be finished by August. By year’s end, decoration and mechanical and electrical installations will be finalized, followed by connection works for Line 7. The total length of Line 7 is approximately 38.56 kilometers, featuring 31 stations, including 18 transfer stations. So far, 90% of the track sections are complete, and the main structures for all stations have been largely finished.
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