Lawmakers on Friday said they were concerned about growing congestion around the Western Harbour Crossing, after changes to tolls made it the busiest of the three harbour tunnels.

Official figures show that since a shake-up of tolls in December, traffic flow at the Western Harbour Crossing has increased by 18 percent to around 103,000 vehicles a day, with queues at peak times getting longer.

Acting Deputy Commissioner for Transport Leung Sai-ho said officials are planning to construct an additional lane at the exit of the tunnel on the Hong Kong Island side.

"Indeed, there's a bottleneck area... I'm sure the project will have a positive impact on the traffic queue and the vehicle speed," he said.

"If we can increase the capacity of the road section, we believe this can improve the overall performance of the Western Harbour Crossing."

Work on the extra lane is expected to begin in the second half of 2025 and to be completed by 2027.