The Transport Secretary, Lam Sai-hung, said on Sunday that the government would have to analyse any changes in traffic flow, before it considered imposing congestion charges at peak hours.

The Western Harbour Crossing transfers to public ownership in August next year, under its 'Build, Operate, Transfer' franchise. All three cross-harbour tunnels will then belong to the government.

Speaking on a Commercial Radio programme, Lam said the government wa planning to raise tolls for private cars using the Cross-Harbour Tunnel and the Eastern Harbour Crossing to HK$30 next summer, while lowering fees at the Western Harbour Crossing to HK$60.

He said this would reduce toll differences and ease congestion.

"Drivers normally will, of course, consider a tunnel's toll when choosing the harbour crossing. But the toll difference with other tunnels is also a consideration. If the other tunnel is less congested, and the toll difference is acceptable, a driver can choose the other option," Lam said.

Some lawmakers have urged authorities to lower tunnel tolls during off-peak hours to encourage drivers to use the tunnels at different times, arguing that the traffic volume during rush hours already exceeds the total capacity of the three tunnels.

But Lam said the government would have to look at how traffic flow changes over the next year before it considers imposing time-varying charges.

"If the current tunnel toll structure and levels are changed drastically, members of the public may not be able to accept it immediately. Secondly, everyone knows that over the past two years we have been in the process of returning to normality, so the current traffic flow at the tunnels might not represent the true situation," Lam said.

"Now if we hastily set time-varying tolls, or even decide on the fare during peak hours to be rolled out in August next year, well I think we should wait and be more cautious."