SINGAPORE - Sprinklers in the Marina Coastal Expressway (MCE) were set off accidentally on Wednesday (May 17) afternoon, drenching the eastbound tunnel.

The water-based firefighting system before the exit to Fort Road was accidentally activated at 12.57pm, the Land Transport Authority (LTA) said.

After verifying that there was no fire, the system was immediately switched off, LTA said.

"Normal traffic condition resumed at about 1.06pm," it said. "LTA is investigating the cause of the incident. We apologise for the inconvenience caused to motorists."

Motorcyclists stopped at the side of the expressway to change into their raincoats as sheets of water rained down on a section of the tunnel leading to Changi.

A video and photos of the scene were circulated on social media on Wednesday.

The expressway was not closed, contrary to rumours that accompanied the images.

This is the second reported incident of sprinklers being accidentally turned on in the tunnel.

A similar incident occurred in April 2015.

In the earlier case, the sprinklers were accidentally triggered by a contractor who was undertaking cleaning and maintenance work on tunnel wall cladding.