KUALA LUMPUR: The Stormwater Management and Road Tunnel (Smart) will remain closed until the authorities are satisfied that the de-watering process is complete. 

As at 6pm yesterday, the water level reading in the tunnel was at 21m. 

The 3km double-deck motorway was closed to traffic on Tuesday to divert water out of the city caused by heavy rain. This move prevented Dataran Merdeka from being inundated.

A spokesman said the tunnel had to be closed to traffic on Tuesday when water flow there hit 150 cubic metres per second. Automatic watertight gates opened to allow the water to pass through the tunnel to a holding basin in Kampung Berembang in Gombak to be released to a storage reservoir in Taman Desa.

This is the second time that the tunnel was completely closed to traffic. In September, the tunnel diverted more than 550,000 cubic metres of water from the city. It was re-opened to traffic after an eight-hour closure.

However, during a moderate storm, motorists can still use the upper tunnel as the flood water will be diverted through the lower tunnel.