A motorist with a noisy exhaust on part of the North-South Elevated Road between Huaihai Road and Xujiahui on January 1.

Another motorist with a noisy exhaust on part of the North-South Elevated Road between Huaihai Road and Xujiahui in the early morning on January 1.

A total of 165 noisy vehicle owners have been caught by the city’s four sonar-based police cameras since the first noise ban came into force in Shanghai in December, traffic police said on Thursday.

The sonar-cameras detect any excess noise emanating from vehicles on the road, often picking up illegal modifications made to exhaust pipes which are designed to make cars louder.

The cameras are now located on major downtown streets such as Huaihai Road and the city’s elevated roads such as the North-South Elevated Road, police said.

From December 1 last year, passenger vehicles with fewer than nine seats are restricted to a noise level of 80 decibels in Shanghai. Violators will be fined 200 yuan (US29.50), with three points deducted from their driver’s licenses. Noisy motorcycles are banned from roads between 9pm and 7am.