On September 12, the Transportation Works Construction Investment Project Management Authority of Ho Chi Minh City (the Management Board in short) reinforced its water pumps and deployed practical solutions to curb the recurring flood risk at the HC1-02 tunnel, which belongs to the An Phu Intersection construction project.
According to the Management Board, prolonged heavy downpours lashed HCMC on the evening of September 10, with rainfall recorded at approximately 123.2mm in the Cat Lai area. By roughly 6:00 p.m., floodwaters surged within the tunnel alongside the approach roads within An Phu Intersection’s perimeter.
Facing the looming threat of deep submersion, Cat Lai traffic police officers, together with consulting units and contractors, temporarily shut down the tunnel and swiftly redirected vehicles to the surface roads above the intersection.
Director Nguyen Anh Minh of the Management Board explained that the primary culprit behind this severe inundation was the relentless, heavy rainfall that completely overwhelmed the existing drainage system. Floodwaters from the surrounding areas surged onto the road surface and poured straight into the pumping station. Consequently, the pumping system was forced to simultaneously handle both the accumulated water inside the tunnel and the massive overflow breaching the station itself.
Notably, the HC1-02 tunnel’s structural portion was completed and subsequently put into operation back in February 2026. Up to now, the total execution volume of the entire bidding package has reached over 90 percent. Because the main pumping system isn’t finished yet, current drainage efforts heavily rely on a temporary pump setup that only meets approximately 70 percent of the originally designed capacity.
When the flooding struck, relevant units orchestrated continuous pumping operations throughout the night and into the morning of September 11. With vital assistance from the firefighting force alongside the Urban Drainage Company (UDC), two suction trucks and a powerful pump with a capacity of 260m3/hour were urgently deployed for reinforcement.
By 1:45 p.m. on September 11, the tunnel was completely drained; sanitation units then moved in to clean up before officially reopening the route to traffic.
For an immediate response, the Management Board explicitly required the construction unit to install an additional 270-cubic-meter-per-hour pump alongside a 200-cubic-meter-per-hour unit. On September 12, they continued mobilizing another robust 360-cubic-meter-per-hour pump to the construction site, substantially boosting the overall drainage capacity for future heavy downpours.
The pumping station perimeter was also heavily fortified with sandbags to effectively prevent external floodwaters from breaching the facility.
Regarding long-term solutions, the Management Board demanded that the construction unit focus intensely on finishing the pumping station, expecting to officially launch the main pumping system by September 22. During October 2026, operational units will proceed to elevate the road surface whilst thoroughly revamping the drainage network across the intersection area.
According to the blueprint, the road surface around An Phu Intersection will be raised by approximately 70-80cm to establish a proper drainage gradient, which ultimately curbs rainwater from rushing straight down into the tunnel entrances.
A robust water collection system running along both curb edges will also be integrated; meanwhile, existing sewer lines that no longer meet drainage demands will be systematically replaced with considerably larger pipes.
This marks the second time in 2026 that the HC1-02 tunnel has suffered a major waterlogging incident. Previously, in February 2026, the tunnel was submerged under roughly 50cm of water after a sudden electrical failure knocked out the pumping station while groundwater continuously flowed backward into the underpass.
For Dr Vo Kim Cuong, former Deputy Chief Architect of HCMC, the capacity to effectively collect, drain, and pump water remains a paramount requirement during the exploitation phase of any underground traffic infrastructure.
“It’s not just about calculating for normal weather conditions,” he explained, noting that the operational strategy must meticulously account for extreme scenarios like torrential rains, sudden power outages, or pumping system malfunctions.
Dr. Vo Kim Cuong argued that while reinforcing water pumps is undeniably a vital short-term fix, addressing the issue permanently requires a synchronized assessment covering the road elevation, water collection trajectory, sewer networks, and the drainage capacity of the entire vicinity.
The troubling instance of floodwaters breaching the pumping station also needs thorough examination to guarantee the facility remains fully operational even under severe downpours.
