Ho Chi Minh City has experienced severe flooding in its tunnels following heavy rainfall, particularly affecting the HC1-02 tunnel at the An Phu intersection. The flooding was attributed to the city's drainage systems being overwhelmed by the volume of rainwater, which reached 123.2mm in some areas.

The HC1-02 tunnel, which was designed with a pumping system to manage water flow, was submerged under 0.5 to 1 meter of water after a significant downpour on September 10. The city's traffic management authority indicated that the existing pumping system could not handle the excessive rainfall, leading to water spilling into the tunnel and causing severe traffic congestion.

Authorities reported that the flooding persisted from the evening of September 10 until the afternoon of September 11, with efforts to pump out the water ongoing. The situation forced the closure of the tunnel, causing traffic jams that extended over 2 kilometers as vehicles were redirected.

Similar incidents have occurred in other tunnels across the city, including the Thu Thiem tunnel, which also faced flooding during heavy rain events. Despite having multiple pumping stations and drainage systems designed to prevent such occurrences, the sheer volume of rainfall has proven too much for the infrastructure to handle.

In response to the flooding, the city's traffic management has committed to improving the drainage systems and expediting the completion of the main pumping station for the HC1-02 tunnel, which is currently only partially operational. Additional pumps have been deployed to assist in managing water levels and prevent future flooding.

The HC1-02 tunnel is a crucial part of the An Phu intersection project, designed to facilitate smoother traffic flow between major routes and reduce congestion in the eastern part of the city. The project is part of a larger infrastructure initiative aimed at enhancing transportation in Ho Chi Minh City.