In the first two days following a strict ban on the practice, Bangkok traffic police issued more than 50,000 tickets to motorists at 15 flyovers and underpasses for illegally changing lanes to overtake other vehicles.
The tickets can result in fines of up to Bt1,000.
Pol Col Kitti Ariyanon, deputy commander of the traffic unit, said that, on the first day alone, Wednesday, 27,514 tickets were handed out, mostly to motorcyclists.
Offenders were caught in the act by a Lane Change Camera System, which involves four automatic cameras at each location.
Eighty per cent of the offences occurred in daylight hours, Kitti said.
On Wednesday, most offences were recorded on the Siriraj Bridge on the outbound lane of Aroon Amarin Road, followed by the bridge at the Din Daeng intersection on the inbound lane of Din Daeng Road and the Huay Kwang tunnel alongside the inbound lane of Ratchadapisek Road.
Kitti noted that the number of violations on Wednesday far exceeded the daily average rate of 7,000 offences during a one-month trial run.
He expressed hope that the number will drop dramatically once more motorists learn about the camera system, as occurred at the flyover at the Government Complex alongside the outbound lane of Chaeng Wattana Road thanks to a police public relations campaign.