City Hall has begun enforcing the doubled 1,000 baht fine for motorcyclists travelling on footpaths, instead of waiting until Saturday as earlier announced.
Bangkok deputy governor Sakoltee Phatthiyakul said on Thursday the surveillance camera network will also be used to catch violators.
The fine, imposed under the cleanliness law, has been doubled from 500 bah in hope of reducing the number of motorcyclists riding on sidewalks.
Mr Sakoltee said the decision was made to enforce it immediately instead of from Dec 1 as initially announced.
Enforcement of the old rate had failed to reduce the number of motorbikes travelling on footpaths, even though about 10,000 riders had been fined about 4 million baht in total since May, he said.
The problem was especially bad in areas not supervised by the Bangkok Metropolitan Administration's inspectors, he said.
"If the raised 1,000-baht fine still fails to have any effect, it will be further increased," Mr Sakoltee said.
Inspectors would impound the motorcycles of riders who could not pay the fine right away. They would be kept until the fine was paid.
The BMA would also identify motorcyclists seen riding on sidewalks on surveillance camera footage and send them letters demanding payment of the fine, Mr Sakoltee said.
The sudden flurry of activity over a practice that has inconvenienced and endangered the city's pedestrians for decades comes after a schoolgirl was knocked down and injured on a pavement on Lat Phrao Road in Wang Thong Lang district on Monday.