Transport Commissioner Rosanna Law said on Saturday that there may be some teething problems when the e-toll system launches in the Shing Mun Tunnels this weekend.

Speaking on an RTHK programme, Law said drivers using the Shing Mun Tunnels would no longer need to stop at booths to pay tolls starting from 5am on Sunday morning, adding that temporary traffic measures would be implemented in stages from 11.30 pm on Saturday in the area and that these would affect several public transport routes.

“But even during the [tunnel] closure, if you are there, there will be police on site to direct you to take other routes,” she said.

Law said drivers may need time to adjust to the e-toll system, as had been the case when the new system was put into effect at the Tsing Sha control point.

"Some drivers still slowed down before reaching the toll booths, which are not in use," Law said.

“There’s one bus driver who forgot to drive into the leftmost lane to drop off passengers, which makes us very nervous,” she added.

She urged drivers to make way for buses moving back into regular lanes after picking up or dropping off passengers in the bus-only lane.

Law said there had been about 50 complaints in the initial three days of the e-toll operation at the Tsing Sha control point, adding that one complainant was charged twice for tunnel fees within a minute.

"Indeed, it is a human error," she said. "During the manual verification process, they checked and entered the data into the system. One of the colleagues might have accidentally entered twice after being distracted for a moment."

Law said manual input of license plates was necessary for vehicles without an e-tag, adding that there's a learning process involved with any technology.