A 1.4km road tunnel connecting Sentosa to the mainland opened yesterday morning.

The one-way Sentosa Gateway Tunnel will allow motorists leaving the resort island to connect directly to Lower Delta Road and Keppel Road.

It is expected to ease congestion at the busy traffic junctions at Sentosa Gateway, Telok Blangah Road, Kampong Bahru Road and Lower Delta Road, especially during evening peak hours and on weekends.

The tunnel, which took nearly 10 years from concept to completion, cost $200 million to build. The Land Transport Authority said previously that the tunnel was built close to the North East Line MRT tunnels and West Coast Highway viaduct foundations, resulting in a height constraint.

In view of this, and for fire safety reasons, it is open only to cars and motorcycles. Buses, goods vehicles and any vehicles higher than 3.5m are not allowed in the tunnel, and have to use existing surface roads.

Correction Note: In an earlier version of the story, we said the tunnel goes under the sea. This is incorrect. The tunnel goes underground. We are sorry for the error.