Transport minister Frank Chan on Friday said the administration plans to consult the public in the last quarter of this year on a proposal for congestion charging at the three harbour crossings.

The government wants to charge private vehicle drivers varying levels of tunnel tolls throughout the day – with those travelling in rush hours paying the highest fees – when it takes back the Western Harbour Crossing from its franchisee in August next year.

Chan was asked at a Legco panel meeting if the administration will set a target for reducing traffic jams at the tunnels, or whether it knows how much the congestion charge will have to be for it to be effective.

The minister said the authorities would collect and analyse traffic data before coming up with a concrete plan.

"We will try to secure understanding and consensus among the stakeholders in the community... and also the Legislative Council, so that on that robust foundation we can carry on [with] the travel behaviour [study] of the community," he told reporters after the meeting.

"As such, we will be able to provide a complete picture for consideration by the Legislative Council and also by the community at large."

Meanwhile, Roundtable lawmaker Michael Tien said the administration should consider offering discounts for carpooling vehicles – when a group of people commute together.

He said, for example, vehicles containing two people could enjoy a 50 percent discount when using the tunnels, while those containing three people could travel through them at no cost.

In response, Chan said the authorities would look into Tien's idea.