(CBS) — Chicagoans are costing the city tens of millions of dollars -– through good behavior.

You heard that right: Good behavior is bad for the budget. Real bad, reports CBS 2 Chief Correspondent Jay Levine.

Remember the old P.T. Barnum line about no one ever going broke by underestimating the intelligence of the American people? Well, Mayor Rahm Emanuel underestimated the intelligence of Chicago drivers, and the city paid for it big time.

On a smooth, wide, well-travelled stretch of Irving Park Road, running between two cemeteries — no homes, no stores, no parking — the city of Chicago is trying to balance its budget.

Each flash means a photo; each photo, a violation. Each violation: a hundred bucks, from red-light and speed cameras.

CBS 2 has learned the speed cameras caught far fewer speeders than expected.

According to the Mayor’s 2015 Budget Overview, there have been “lower than expected violation rates.”

How much lower? Fifty million dollars lower. Emanuel’s administration had figured on $90 million in fines to help balance this year’s budget, but they can only count on $40 million. That’s a $50 million shortfall, putting pressure on the next spending plan.

“It was a combination of the camera company’s salesmanship and the city’s greed,” says camera critic Barnet Fagel.

The city was expecting a nearly $100 million windfall by flooding the city with the speed cameras, using proximity to schools and parks as justification. The speed camera on Irving Park is listed as close to Challenger Park, which actually looks more like a parking lot — and is, during Cubs games.

At Clark and Irving, the strobe light of a red-light camera flashed 14 times in the 10 minutes CBS 2 watched. You do the math.

Critics have said red-light cameras don’t enhance safety and are more of a cash grab for the city government.

A report by Inspector General Joe Ferguson maintained “the City cannot prove red-light camera locations are based on safety considerations.”

And a University of Illinois at Chicago study concluded “red light cameras are not effective in improving safety.”

It may be too soon to tell if speed cameras have made us safer. But drivers have certainly gotten wise to them, leaving a $50 million dollar hole in this year’s budget.