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July 27, 2006

London case study of widespread video monitoring

The main center of the city of London is two-and-a-half-square kilometers. In 1998 a network of cameras was installed that provides comprehensive video coverage of a large part of the City. Every vehicle entering the area is photographed, its license plate checked against a national police database, and an image of its driver stored for posterity. Earlier this year, the New York City Police Department announced that it was installing more than 500 cameras around the city and pushing for its own ring of steel to protect lower Manhattan.

As part of the original system, they reduced traffic coming into the city and reduced the number of streets for entry. Unexpectedly, the introduction of cameras had a big effect on the environment. The traffic-channeling measures not only slowed traffic but also reduced the number of vehicles entering the area, substantially improving air quality. It also allowed city planners to turn many roads that were no longer accessible into pedestrian malls. The result: a more pleasant working environment for many Londoners.

Today, the accuracy of automatic license plate recognition approaches 100 percent for cars traveling at ordinary city speeds in a wide range of lighting conditions. One major challenge for surveillance officials is handling the data the London cameras produce. The system consists of over 200 cameras, each sending a 3.8‑megabit-per-second MPEG video feed to the control room of a police station in the heart of the City. Processing this data in real time requires 122 IBM xSeries servers with a total storage capacity of 200 terabytes.

Last year, the cameras recorded 38 million vehicle entries into the area. Of these, 91 000 were listed for infractions on the national computer; 4161 warranted police action, leading to 539 arrests. Many serious crimes were uncovered as a result of stopping a vehicle for a minor violation. “It gives us a way in,” says Mellor. “With good police work, a traffic offense is just the beginning.”

An example, a black Porsche Cayenne that was flagged by the computer last 13 February because the driver had not paid the car’s leasing bills. The police stopped the vehicle, searched it, and found US $20 000 in the glove compartment, triggering a major money-laundering investigation.

One thing that hasn’t been much of a public concern is privacy. The London terror attack was not detered but the system accelerated the investigation.

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