First yellow flashing right turn arrow arrives in Utah

LEHI — Northern Utah County is developing at a rapid pace, emerging as a new frontier of the high-tech industry. In addition to retail attractions such as Cabela’s and the Outlets at Traverse Mountain, the area around I-15 at Timpanogos Highway (SR-92) has been dubbed the “Silicon Slopes,” attracting businesses who want affordable office space, a reliable talent pool from area universities and the high quality of life Utahns enjoy with a variety of outdoor recreation options just minutes away.

With all this development, UDOT continually evaluates how to improve traffic flow through the I-15/SR-92 interchange.

The latest update to the interchange is also a first in Utah: crews installed the state’s first flashing yellow right turn arrow at the northbound I-15 off-ramp to eastbound SR-92 in Lehi. You have probably driven through dozens of flashing yellow left turn arrows, where turning traffic yields but may make a left if there is no oncoming traffic. So why does the flashing yellow right turn arrow work at this interchange?

A flashing yellow arrow on a right hand turn on SR-92 allows traffic to flow more freely in a fast-growing part of Utah County.

A flashing yellow arrow on a right hand turn on SR-92 allows traffic to flow more freely in a fast-growing part of Utah County.

 

“The right turn goes into a lane that takes people to the SR-92 commuter lane, but a lot of people want to make a left into Adobe or Cabela’s,” said UDOT Region Three Signal Engineer Adam Lough. “We were seeing traffic back up and drivers getting frustrated because people who wanted to cross traffic to get to the left lane would be stopped on a green light. The flashing yellow signals a yield condition for drivers who want to move to the left lane on SR-92 as well as for the queue of traffic on the ramp.”

Now when the light is green, there is no eastbound traffic for drivers to weave through to move left; and during the flashing yellow, drivers who want to move left must wait for a safe opening in the traffic flow. Drivers who want to access the SR-92 commuter lanes from the I-15 northbound off-ramp still get impatient at times, but Lough said the flashing yellow right turn arrow has improved the traffic flow. “This provides a safer condition and has reduced the amount of backing on the ramp.”

Lough developed the idea of using a flashing yellow right turn arrow to address the traffic problems at this interchange ramp. Although UDOT had never installed anything like it, Lough suggested that it would be the best solution and worked with Traffic Operations Center staff to implement it. So far, he is pleased with the results.

“I am always looking for better ways to do things,” he said. “It is rewarding to see how changes like this make people’s commute a little better.”

Lough said the signal is almost always green or flashing yellow, but it briefly turns solid yellow and red as part of the signal’s cycle. The pedestrian button also triggers the red arrow.

“There is quite a bit of pedestrian traffic between the employment centers and retail outlets on either side of I-15 in this area,” Lough said. “Drivers really need to be on the lookout for pedestrians and bicyclists moving through this interchange.”

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