Yellow means caution. That's how the Minneapolis City Council should approach today's vote on "photo cop," a proposal to install cameras at 24 problematic intersections as a way to track down and penalize drivers who run red lights.

The problem, according to Minneapolis police, is that too many motorists are running red lights at the risk of their own safety and the safety of pedestrians and other drivers. Why? Lax enforcement. For the better part of two decades, police have had to shift focus from traffic to crime. Motorists have learned that, except in high-crime neighborhoods, they can get away with all sorts of reckless habits. Now, in times of severe budget constraint, the police are even less able to afford to station officers on traffic duty.

But cameras, they say, can do some of the work. They can identify the offending vehicles by their licence plates and initiate the sending of a traffic ticket by mail. Challenging a ticket would be the responsibility of the vehicle's owner.

Skeptics detect a motive other than safety: the depleted city treasury. They suggest that private vendors are selling Minneapolis a "safety package" that just happens to make money -- potentially lots of money -- for both for the vendor and the city.

Their evidence includes a 2001 position paper from former House Republican Leader Dick Armey of Texas. Armey's analysis cites news reports showing that New York City used photo cop to collect $9 million in fines on 400,000 tickets in 2000, that Washington, D.C. anticipated revenues of $16 million a year from 37 cameras in 2001, and that San Diego collected $6.8 million from a single camera during an 18-month period.

Other evidence includes a media report from Portland, Ore., intimating that one suburb, Beaverton, may have shortened the yellow lights at intersections covered by cameras in order to increase its take.

On balance, however, we think cameras are a good idea. Over the last four years, 49 people have been killed and 11,800 injured in crashes at Minneapolis intersections. That's appalling. Those crashes have cost people and the wider society $139 million in car repairs, medical service and other expenses.

Yes, cameras can be abused. Their advocates at City Hall owe Minneapolis drivers and residents a full explanation for their need and assurances that they'll be used honorably. Safety, not moneymaking, ought to be the rationale. When a private vendor is selected, it ought not to be extravagantly rewarded. No yellow lights should be shortened to increase the likelihood of violations. The entire program should be transparent and closely monitored.

People have good reason to be suspicious of cameras. But, given the current shortage of police officers, photo cop can be a smart investment if fairly, prudently and accurately employed at the city's most dangerous intersections.