The government on Monday said it remains open to the idea of building a fourth cross-harbour tunnel, after it earlier released a new blueprint outlining Hong Kong's transport strategy for the next two decades.

The fourth tunnel was first proposed alongside the construction of Kau Yi Chau Artificial Islands in the 2022 Policy Address to link Hong Kong Island West and the northeast of Lantau Island via the man-made island.

Assistant Transport Commissioner Leung Sai-ho told an RTHK programme that the administration is currently seeking alternative plans to build the tunnel following the shelving of the reclamation project last September.

"In the previous plan, we were quite confident in the technical feasibility of constructing the route for the tunnel. However, as we do not currently have a concrete timetable for the construction of the islands, we are trying to find an alternative route that could connect to Hong Kong Island," he said.

"Apart from considering technical feasibility, we also have to look into traffic demand. A cross-harbour tunnel is important infrastructure, so we also have to consider the finances," he added.

On peak-hour traffic in tunnels, Leung pointed out that it is difficult to completely eliminate congestion, but time-varying tolls being implemented at the three harbour crossings since 2023 have helped with diverting traffic during peak hours.

He said his department will continue to find alternatives to solve the issue, such as maximising traffic volume at the Western Harbour Crossing by adding a new traffic lane at its Hong Kong Island Bound Exit.

In terms of building smart demand-responsive public transport – which aims to have operators provide more efficient routes and flexible schedules in response to demand – Assistant Transport Commissioner Patrick Wong said a mobile application will be made available for passengers to indicate their intended departure times and destination.

He said operators can then provide specific routes accordingly, for example buses from the airport to North Point without having to pass through Sheung Wan, in order to boost traffic flow and passenger experience.