In the heart of Malaysia, monsoon rains and the confluence of the Klang and Gombak rivers used to paralyze the capital with destructive floods. The answer from modern engineering was not to build gigantic dikes or widen riverbeds at the expense of the city, but to design a world-first, dual-purpose infrastructure: the SMART Tunnel (Stormwater Management and Road Tunnel), opened in 2007.
With a total length of 9.7 kilometers and an internal diameter of 13.2 meters excavated by colossal hydroshield tunnel boring machines, the genius of the project lies in its three-level central section. Under normal conditions, the upper two decks operate as a busy two-way highway that eases congestion on the approaches to Kuala Lumpur, while the bottom channel remains reserved for draining moderate water flows.
However, when telemetry stations detect an imminent flash flood, the system triggers an unprecedented electromechanical protocol:
- Express evacuation: Automated gates close off road access, and the tunnel empties of vehicles in a matter of minutes, guided by smart signaling.
- Inspection and sealing: Infrared cameras verify that the roadway is completely deserted before watertight steel bulkheads hermetically seal the traffic decks.
- Controlled flooding: The entire tunnel opens its floodgates to the torrential river, turning into a massive pressurized aqueduct capable of channeling three million cubic meters of water into retention reservoirs on the outskirts.
After the storm, washing and ventilation crews clean out sediments within a few hours to reopen traffic, proving that a highway can transform into an underground hydraulic lifesaver.
Source: Institution of Civil Engineers (ICE) / SMART Tunnel Project Malaysia
