SINGAPORE, May 31 -- Singapore's Immigration and Checkpoints Authority (ICA) has introduced enhanced safety measures at Woodlands Checkpoint to improve traffic management during peak-hour contra-flow operations, following a collision on May 24.

The accident occurred at around 5.30am when a Singapore-registered car heading towards Malaysia collided head-on with a Malaysia-registered bus travelling into Singapore.

The car's driver and three passengers were taken to hospital conscious.

The collision happened before safety barriers were set up to divert departing car traffic from the reversed-flow lane meant to ease incoming vehicle congestion.

The contra-flow system involves temporarily reversing the flow of one of the departure lanes, k...