nothin Traffic Signal Revolution Breaks The Chains | New Haven Independent

Traffic Signal Revolution Breaks The Chains

Thomas MacMillan Photo

With help from traffic engineer Bijan Notghi, more of New Haven’s traffic signals will soon break free from the chains that bind them and free drivers to enjoy one green light after another.

For the past decade, Notghi (pictured) has been working to overhaul the city’s aging traffic lights, some of which are so old the city had to chain them in place last year so they won’t fall on passing cars. Since 2003, Notghi has overseen the modernizing of nearly 200 traffic signals in town, out of 292 total.

City lawmakers last month approved the acceptance of $4.2 million in state funding to pay for 18 new traffic signals at intersections in the Hill and City Point, starting in spring 2013. That work will take place in two phases, of 12 and 6 intersections respectively. Notghi has his sights set on $2.9 million more federal and state dollars to start replacing 15 new signals downtown — also in two phases — starting in spring, 2014. On top of that, nine intersections will get new signals in the next couple of years as part of the city’s Downtown Crossing project.

All the new signals are connected by fiber optics to Notghi’s central traffic command station in the basement of the Hall of Records on Orange Street. Twelve video monitors line the walls and a large stack of servers hums near Notghi’s desk. The technology allows him to monitor and tweak the lights to allow traffic to flow freely through the city. All the new signals are synced so that a driver going at the speed limit should hit one green light after another.

The new signals also include several other features that reflect advances in traffic-control technology over the years. Today’s intersections have stronger supports, crosswalks for the blind, lights that can see you coming, and video cameras that let Notghi see if traffic is getting backed up — and let the cops look for evidence of crimes.

Unchained Lights

An ancient aluminum truss arm at Chapel and Church.

Some of the city’s current lights date from as long ago as the 1950s and 60s, said Notghi. They’re held aloft by now-ancient aluminum truss arms that extend over intersections. The arms are short and can’t handle huge loads.

The lights on those arms are mounted so that they can swing in the wind. Over time, this can wear down the connection.

Concerned about its aging, dangling traffic lights, the city several years ago installed chains on the lights as a fail-safe measure. If the attachment fails, the chains will prevent a light from plummeting through the roof of a car passing underneath.

These things are heavy,” Notghi said. The lights may look small when they’re hanging up, but they are actually quite large. They can do some serious damage.”

Another problem with the old, swinging lights is that over time they can become misaligned. A traffic light is most visible when it faces directly toward oncoming traffic. If it moves even just 20 degrees off to one side, it can become much harder for drivers to see, Notghi said.

A new steel support at Church and Crown.

The new lights are mounted on a steel arm that comes straight out of a steel pole. The lights are fixed in place so there’s no chance of twisting,” Notghi said. Steel supports are much stronger, can support more weight, and require less maintenance, he said. While the old aluminum poles went only seven or eight feet into the ground, the new steel supports extend 15 or 16 feet down. Like a tree with deeper roots, they can withstand stronger winds.

Eyes In The Sky

Twenty years ago, the city introduced a central control system connecting 240 of the city’s 292 traffic signals to a main command point, via telephone lines. With the central system, the city is able to control the lights remotely and see what they are all doing at every moment.

Notghi makes a distinction between traffic lights” and traffic signals.” Traffic signal” refers to the timers and electronics that tell the lights when to change colors. Traffic lights” are the things that tell drivers when to stop and go.

Of the city’s 240 wired signals, 138 have been upgraded to fiber optic connections. That means the city owns the infrastructure, which travels underground rather than through phone lines. Fiber optic cables present a couple of advantages.

First, the city doesn’t have to pay a monthly phone bill for traffic signal communications.

Second, the fiber optic cables have far more bandwidth. It’s essentially unlimited,” Notghi said. That means the city can put in a number of video cameras to monitor traffic. Phone lines don’t have enough bandwidth to handle any video.

The city now has about 44 of those incident management” cameras, which record 24 hours a day and can pan and zoom. The footage is stored for 15 days, then erased, Notghi said. The video feeds are also connected to the police station, where cops can use them to look for evidence after a traffic accident, Notghi said. He said the police department has a number of other cameras in town that the city is looking to hardwire into the fiber optic system.

Sensitive Signals

A video sensor on Crown Street.

Most of the city’s signals are equipped with in-ground sensors, which detect when a car is stopped at an intersection, waiting for the light to change, and trigger the light to change. In-ground loop” sensors are easily disrupted by disturbances like road work, including routing milling and paving.

The city installed loop detectors starting about 30 years ago, Notghi said. Most of the intersections downtown, apart from the new signals at Gateway, do not have them. But outside of downtown, 99 percent of signals have sensors, Notghi said.

Of those sensors, the ones at 93 intersections are video sensors, Notghi said. The video systems have none of drawbacks of the loop sensors, and a number of advantages.

Different from the video cameras, the video sensors are fixed, on the area where cars stop to wait for a signal to change. The sensors do not record video, they simply detect when and how many cars are waiting. They can also log traffic counts of how many cars pass through an intersection, which the Notghi can use to tweak the timing of the light.

Notghi pointed to a monitor on his desk showing a live feed of cars waiting on Fowler Street at Amity Road. A green box on the screen lit up as cars arrived at the intersection. A green bar lit up when cars passed through the intersection.

Notghi said the signal is set up to turn green for five seconds for the first car, then two seconds for each additional car, up to a maximum of 15 to 20 seconds.

The system is designed to allow traffic to flow on main thoroughfares, like Amity Road, only stopping when there are cars waiting on a side street. Theoretically, that should mean that no one ever has to stop and wait at an empty street.

The whole city is not there yet, however. Drivers still have to stop for no apparent reason by seemingly arbitrary light-cycles at some intersections in town, like Whalley and Winthrop. Notghi said that’s due to faulty loop sensors that can’t tell when cars are waiting or not.

It screws up all the coordination between the lights,” Notghi said. When a loop detector is broken, the light reverts back to recall mode.” It turns green every cycle, whether cars are waiting or not, and stays green for the maximum duration. That’s the most major issue with those lights.”

Construction on Whalley has disrupted a lot of those sensors, Notghi said. He said Goffe Street has the same problem. Eventually, as loop detectors continue to break, the city will replace them with video detectors, Notghi said.

It should be smooth sailing through the new traffic signals around Gateway Community College downtown, and through most of Winchester Avenue, and around Southern Connecticut State University. People driving the speed limit there should find the lights tend to turn green as they hit them, he said.

Blind Crossing

The city’s newest traffic signals aren’t just for cars. They’re equipped with updated crossing signals for pedestrians, featuring countdowns to show how much time is left to cross.

The crossing signals also include automated noises for blind pedestrians. A beeping sound leads the blind to the crosswalk button. A voice intones, wait” when the button is pressed. And a clicking sound can be heard when it’s time to cross.

The city has such crosswalks around Gateway and Southern and on Martin Luther King Jr. Boulevard, Notghi said.

Notghi said he has another 50 traffic signals left to upgrade over the next six or so years. But his work won’t end there. It’s like the Golden Gate bridge,” which needs another coat by the time painters have gone from one end to the other. He’ll need to start over again, introducing whatever the latest technology is.

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