Getting There: Timing everything with traffic lights - East Valley Tribune: East Valley Local News

Getting There: Timing everything with traffic lights

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Posted: Saturday, March 8, 2008 9:04 pm | Updated: 12:00 am, Sat Oct 8, 2011.

Larry Burgo suspects Scottsdale isn't doing enough to keep drivers from getting stuck at red traffic signals.

The idea occurred to the Scottsdale resident after driving his son to daily medical treatments for weeks in a row and finding the signals didn't seem to match the flow of traffic. It's a problem in other cities, too, he said.

"Everybody is complaining about the smog and the brown cloud," Burgo said. "Well, we're adding to it when we're sitting at intersections on main streets."

Scottsdale uses sophisticated software to synchronize signal timingand with varying traffic flows at different times, said Paul Porell, the city's traffic engineering director.

Plus sensors and cameras let traffic engineers adjust timing during special events or after a crash changes normal traffic flows.

But the city's geography poses tough problems.

Scottsdale's long, narrow shape translates into lots of north-south traffic and an unusually large demand for drivers to make left turns, Porell said.

The city had to build double-left turn bays in some places. For safety reasons, that usually means drivers can only turn on a green arrow.

"But one of the compromises is that additional green time is lost to through-traffic," Porell said.

It's easier to coordinate signals when they're spaced at even increments, such as every half-mile.

But some roads have signals at irregular increments, making it impossible to time the signals in an ideal way.

The city sets signals to favor the direction of a road carrying the most traffic at various times of the day, Porell said.

Computer models help the city find the best timing, but Porell said mathematical realities limit what traffic engineers can do.

Valley cities coordinate timing with neighboring communities, said Jerry O'Farrell, an intelligent-transportation systems analyst for Mesa.

But even within a city's own boundaries, some roads carry such heavy traffic volumes that it's impossible to coordinate signals so everybody can get to an intersection at the perfect time.

Even small things disrupt signal timing.

Construction can damage traffic sensors or cut communication lines that help traffic engineers monitor traffic. Restrictions can slow traffic and alter normal traffic patterns.

Then there's plain old congestion.

Some roads and intersections can't handle the crush of traffic regardless of technology or timing, O'Farrell said.

"The coordination at that point ceases to exist, realistically, when traffic is that heavy," he said.


We often get the word about large road construction projects and closures in news stories as well as radio and TV traffic reports. But it's the little stuff that can get you. Queen Creek High School students arrived at least a half-hour late last month because a road was unexpectedly closed to paint new stripes on it, school officials said.

So how do town and county officials keep residents informed about closures and restrictions?

"We rely on you," Gilbert spokesman Greg Svelund told me.

Gilbert's Web site has a listing of road restrictions, but it's based mainly on private contractors' permit applications. Most of the road construction in Gilbert these days is associated with private development. That means the dates listed are estimates supplied by contractors and aren't always reliable. But still, it's better than nothing. And I've found the items listed in red to be reliable so far. Check it out for yourself at

In Queen Creek, residents can get updates online, by phone, by e-mail or by reading the town's monthly newsletter.

Dee Anne Thomas, a spokeswoman for Queen Creek, said it's a challenge keeping residents informed about projects that change often and quickly. "There are so many variables that impact the latest development. So things can happen very quickly, they can change very quickly," she said.

You also can get construction information by calling the town's traffic hot line at (480) 358-3132.

For those with Web access, your best bet is the town's Web site at Click on "traffic updates" at the bottom of the page for the latest from Queen Creek's traffic engineers. Or you can sign up to receive traffic alert e-mails - just click "sign up for eNews" at the bottom of the screen.

Pinal County also has traffic alerts posted on its Web site at The county also has a road information line at (520) 866-6078.


Ocotillo Road from Val Vista Drive to Greenfield Road is closed until late March for an ongoing county road project.

Queen Creek Road will be closed from Arizona Avenue to McQueen Road while Chandler crews expand that road to six lanes. The closure is scheduled to last until Sept. 28.

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