Technology makes emissions testing easy

New sensors which scan the emissions of every passing vehicle can do the job far more efficiently than the traditional stop-and-test technique employed in the UK, as demonstrated on the streets of London this week.

"Traditionally vehicles emissions have been done with a portable analyser with a probe," said Duncan Mounsor, operations director for Enviro Technology, the company marketing the American-made Accuscan 4600 in Britain.

"Local authorities will have an environmental health officer and will also need the services of the police, who would direct single vehicles into a lay-by where an environmental health officer will use a portable analyser and physically put a probe up the tail pipe.

"That system is quite labour intensive, and it needs the services of the police as local authorities can't stop traffic.

"With the best will in the world, you can't do that many vehicles - you're looking at about a dozen an hour."

He claims the Accuscan 4600 is far more user-friendly and more representative, building up a more accurate picture because rather than taking a random sample of a few of the vehicles passing by, it logs the emissions of every one - up to 4,000 an hour.

The set-up involves a camera to snap a picture of the vehicle, and more importantly its number plate, lasers to measure speed and acceleration, ultraviolet and infrared beams to measure the gases themselves, as well as the 'smoke factor' that gives and indication of particulate levels.

The equipment is smart enough to take background levels of pollution into account and is usually set up to only measure the emissions of vehicles which are accelerating. "There's not much coming out of the exhaust if you haven't got your foot on the pedal," as Duncan put it.

Levels of carbon dioxide, nitrogen dioxide, carbon monoxide and hydrocarbons are all recorded by the device.

While the emissions monitoring system is clearly less labour intensive and scans far more vehicles than the traditional roadside trap, the company admits it was not a cheap piece of kit - not in terms of initial outlay, in any case.

But Chris Stock, vice president of the US company which manufactures the equipment, Environmental Systems Products, said the system soon pays for itself.

"It's cost efficiency once you set up a system of remote sensors is very, very high," he told edie.

"By the time you've processed the data and mailed out an automated notice to the owners of gross emitting vehicles, it's going to cost you $1-2 per vehicle. That's a lot cheaper than roadside testing."

Although the system is up an running in several American cities, it is new technology for the UK.

Duncan said he imagined it, or something like it, would be needed once low emissions zones were introduced in the capital and elsewhere.

Remote sensors could be set up alongside existing congestion charge cameras and anywhere else they might be needed, to build up a city-wide picture of the private fleet and its emissions.

"You've got Ken Livingstone saying he will charge high-emissions vehicles to enter the city, but how is he going to know?" said Duncan.

"London has dozens of static air quality monitoring sites and they provide a useful general picture of whether efforts to bring down pollution are working but they don't tie the problem to particular vehicles. Our system does."

Sam Bond


air quality | Data | technology


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