The amount of vehicles using the busy Cross-Harbour Tunnel fell during Wednesday morning's peak hours, while traffic increased at the Western Harbour Crossing after cheaper tolls for private cars and taxis came into effect there.

The Transport Department said traffic at the Cross-Harbour Tunnel was down 4 percent compared to usual, and there was a 1 percent drop in the number of vehicles using the Eastern Harbour Crossing.

Traffic at the Western tunnel rose 3 percent, officials said.

They added that between 7am and 10am, a total of about 44,000 vehicles crossed the harbour via the three tunnels – a similar number to usual.

A spokesman for the department said taxi drivers in particular appeared to have switched routes, with 50 percent more using the Western Harbour Crossing (WHC) during the small hours of Wednesday, and 20 percent more during the peak hours.

But this wasn't all good news, the spokesman noted.

"Due to the increase in the number of taxis paying tolls in cash to use the WHC, the manual toll lanes are slightly busier than usual during peak hours," he said.

"We believe that with the implementation of HKeToll on August 6, drivers will not have to stop to pay tolls, and the traffic conditions of WHC will be smoother."