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Car detectors

Traffic cameras help ease congestion at busy intersections
and can help ease the strain on gasoline budgets. But some warn they
won’t solve all the transit problems of a growing city.
Tuesday, September 28, 2004 | 12:00 a.m. CDT; updated 12:09 p.m. CDT, Sunday, July 20, 2008

About five years ago, small cameras began sprouting up at intersections around Columbia.

Some drivers have mistaken the new additions as red-light cameras, which are used around the world to record traffic violations.

“There’s a misconception,” said Sgt. Tim Moriarity, head of the traffic unit for the Columbia Police Department. “They’re not red-light cameras.”

In fact, the cameras detect cars stopped at an intersection and send a signal that changes the light to green. The cameras in Columbia are owned by the Missouri Department of Transportation.

The city is expected to buy its own traffic camera next year for the Broadway and Trimble intersection, and city engineers are evaluating other sites for the technology.

The costs of congestion

According to a national study of 85 metro areas by the Texas Transportation Institute, in 2002, traffic congestion caused 3.5 billion hours of delay, wasted 5.7 billion gallons of gas and cost the nation’s economy $63 billion in productivity.

Last year, in a city-sponsored survey, respondents ranked traffic congestion as the problem that “should receive the most emphasis over the next two years.” Respondents ranked it more important than code enforcement, quality of public health services, and parks and recreation.

“Everybody’s concerned about the amount of traffic,” City Councilman John John said. “There’s a lot of concern about running red lights, speeding and congestion.”

While Columbia does not yet have a major congestion problem, engineers here are just as concerned about the economic impact of cars stuck in traffic or waiting at signals.

“Economically, if you’re stopped at a signal, you’re burning up gas, creating emissions,” said Richard Stone, a traffic engineer for the city of Columbia. “You’re also not getting to your destination.”

Keeping the traffic moving

Cameras are just one of the technologies aimed at keeping local drivers on the move. Since the 1960s, finely tuned coils buried beneath the pavement at intersections have been detecting cars and sending signals to traffic signals — a process known as inductive loop detection.

Interconnected traffic signals along Forum Boulevard in Columbia allow drivers to cruise through four consecutive green lights — but only if they travel the speed limit.

“Sometimes people don’t realize they would have arrived on green if they went the speed limit,” said Mark Virkler, an MU professor of civil engineering.

Virkler’s department has been working with the transportation department to devise ways to make travel in the state safe and efficient. Engineers study traffic volume before placing a signal at an intersection. Before deciding to equip the signal with timers, they interconnect it with other signals or install cameras or inductive loop coils.

The choice of technology depends on the intersection. Coils may be better for smaller intersections because installation and maintenance requires cutting into the pavement and shutting down lanes.

While the coils themselves are relatively inexpensive compared to cameras, which cost $25,000 per intersection, the installation and maintenance of cameras do not interfere with traffic.

“You just have to evaluate it on what the traffic is like,” Stone said. “If you’re at a volume where you’re going to need to put in new loops so you can detect cars earlier, you’d have to weigh the cost of doing that versus the cost of cameras versus the cost of versatility.”

Engineers also use software programs to simulate the impact of extending a red light by one second or the impact of a new Wal-Mart.

Highway department traffic engineer Matt Meyers said the state will continue to place cameras at major intersections as the existing coils, which can last 10 to 15 years, become brittle and fail. Meyers said the cameras should last 10 to 30 years.

"It's a city, not a town."

Advances in wireless and fiber optic technologies will continue improve the reach of cameras. Stonesaid the Transportation Department is considering cameras for I-70 that can monitor traffic in real time.

“They can be interconnected through fiber optics and actually show you the location,” he said. “You can see several locations at once and see if there’s a problem some place.”

But while almost everyone agrees that technology helps move cars through intersections, it can’t fix every traffic problem. In a growing city like Columbia, more and better roadways are the best way to combat congestion, Moriarity said.

“As the city grows, we are going to have to make adjustments,” he said. “I believe we need more roadways like Stadium (Boulevard). I know we have a lot of resistance to that, and I can understand, but from a traffic standpoint Columbia needs more roadways going from east to west. It’s a city, not a town. It’s a city.”


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