Vehicle owners who are slack with maintenance or who fill up with poor-quality fuel may soon have nowhere to hide if their vehicles are spewing smoke.

The National Environment Agency (NEA) is testing a new camera system that can detect and identify smoky vehicles on the roads.

The automated system was tried out in Hougang earlier this year, and is now being tested in Loyang.

A pair of cameras was mounted on a pedestrian overhead bridge in Loyang Avenue on Sept 20. The set-up will remain there until December.

An NEA spokesman said the cameras are part of research and development efforts "to leverage sensor technology for monitoring emissions from vehicular sources".

The surveillance system comprises "customised prototype cameras coupled with sensors, developed in collaboration with technology solution providers", the NEA said. It refused to say more about the system, such as how it works and whether it detects only black smoke from heavy vehicles, or any kind of smoke from any vehicle.

However, observers reckon the system is similar to something Australia implemented a decade ago on a highway outside Sydney.

GOOD MOVE I think it is a good idea. Even though we have vehicle inspections, a lot can happen between inspections. Diesel vehicles, if not well maintained, can be smoky within three months. Also, we have a lot of old ones around. MR JAESEN NG, a commercial vehicle owner who runs a food business.

According to information on the New South Wales Roads and Maritime Services website, its system was installed in June 2006 at a cost of A$3 million. "The smoky vehicle camera system is designed to detect, identify and record smoky vehicles using smoke detectors, video and still cameras... and optical character recognition software to capture the identity of large smoky vehicles," the website said.

In Singapore, acting against owners of smoky vehicles remains an uphill battle despite mandatory vehicle inspections and legislated fuel quality. Official data shows an average of 9,000 summonses were issued annually in the past three years.

Asian Clean Fuels Association director Clarence Woo said implementing such a camera system "would be great" because of manpower constraints.

He added that such a system is necessary as there may be ways for fleet owners to evade detection at inspection centres. With this system, "vehicle owners will need to maintain their vehicles at all times... rather than wait for the annual inspection", he said.

Commercial vehicle owner Jaesen Ng, 63, said: "I think it is a good idea. Even though we have vehicle inspections, a lot can happen between inspections.

"Diesel vehicles, if not well maintained, can be smoky within three months. Also, we have a lot of old ones around."

Mr Ng, who runs a food business and owns two vans, both less than five years old, said the biggest culprits are Malaysian trucks. "Almost every one of them is smoky. But there is nothing much we can do. We need the goods they bring in."