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UDOT celebrates 100 years of the Utah-born traffic light

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SALT LAKE CITY — Utah is the birthplace of some great inventions: television, the artificial heart and the pump shotgun, to name a few. But you probably didn't know that the first electric traffic signal was invented in Salt Lake City 100 years ago.

Electric traffic control all started with an invention of policeman Lester F. Wire, installed in the middle of the intersection of 200 South and Main Street.

"He was an officer out in the middle of an intersection. He had cars and trucks and buggies and trolleys driving past him, and he just didn't feel safe," explained Eric Rasband, traffic operations manager at the Utah Department of Transportation.

The first traffic signal was "a birdhouse made of plywood," UDOT executive director John Njord said. "(Lester F. Wire) painted it yellow and put 6-inch holes on either side."

So, Wire solved the problem with a manual traffic signal.

To celebrate the signal's 100th birthday, UDOT showed off a replica of the original as part of a history display in the agency's Traffic Operations Center.

"It was a birdhouse made of plywood," UDOT executive director John Njord said, pointing out the replica. "He painted it yellow and put 6-inch holes on either side."

Wire then dipped light bulbs in red and green paint. "He just flipped the switch right there, from red to green," Njord said.

In 1912, 200 South and Main was the busiest intersection in Salt Lake City — and it remains one of the busiest today.

At first, Wire was ridiculed for the invention. But five years later, Salt Lake City boasted the first interconnected traffic signal system in the United States with six connected intersections controlled simultaneously from a manual switch.

Utah traffic light timeline
  • 1912 — The first signal using lights was installed at the intersection of Main Street and 200 South in Salt Lake City.
  • 1917 — The first interconnected traffic signal system in the world was installed in Salt Lake City.
  • 1987 — Utah's first traffic signal system capable of making remote signal timing changes installed.
  • Late 1980s — Emergency vehicle preemption was installed, allowing emergency vehicles to preempt the light to green.
  • Late 1990s — Countdown pedestrian timers at intersections were introduced.
  • 2001 — The first LED traffic signals installed.
  • 2005 — UDOT began utilizing radar detection at intersections.
  • 2007 — UDOT installed flashing yellow arrows for permissive left turns.
  • 2010 — Utah's first Diverging Diamond interchange installed in American Fork.
  • 2012 — UDOT currently owns 1,200 traffic signals and 52 ramp meters.
Source: UDOT

A century later, the UDOT Traffic Operations Center integrates some of the most cutting-edge technology available.

"We're one of the few states in the nation who have the ability to talk to every traffic signal that is connected," Rasband said.

The network integrates 1,500 signals statewide, along with 500 cameras and 100 electronic signs. Rasband can control traffic in St. George, Logan or up on Foothill Drive in Salt Lake City as Ute fans flood in for the football game.

A coordinated traffic management team at the stadium and at the Traffic Operations Center can reduce delays more than 40 percent, according to a recent study.

Traffic innovation continues today in Utah, from continuous flow and diverging diamond interchanges to sensors in the road that calculate the number of cars and make signal adjustments.

"We like the technology. We are engineers, we are drawn to it," Njord said. "But it's not only about the technology, it's about how it can impact people for the good."

So, what's the next innovation on the horizon? Cars that drive themselves and communicate with other cars and the roadway network. Imagine what Lester Wire would think of that.


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Jed Boal


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