Ever wonder how the diverging diamond interchange works? Here’s how
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REXBURG — The new diverging diamond interchanges in Rexburg have left some residents with questions, but EastIdahoNews.com has answers.
Rexburg exits 332 and 333 on U.S. Highway 20 now have diverging diamond interchanges, an unconventional yet streamlined way to direct traffic, according to transportation officials.
Diverging diamond interchanges involve traffic lanes temporarily crossing onto the opposite sides of the road. This allows traffic to turn left onto and off U.S. Highway 20 without waiting for an opening.
Why are the exits adopting diverging diamond interchanges?
Previously, both Rexburg exits were prone to traffic back-ups and delays from traffic lights. Officials say the new design mitigates those issues, making the road safer and travel faster.
“Trying to shoot the gap to make a left turn as you get off or whatever, all those different points of conflict — it answers them with a different kind of movement, a more free-running and controlled movement,” said Sky Buffat, the public information officer for the Idaho Transportation Department.
The roads also have an additional lane to turn onto the U.S. Highway 20 ramp. Previously, as drivers neared the traffic light, they could choose between the right or left lanes depending on where they would turn. Now, the ramps split off into three lanes to relieve congestion onto the highway.
Can I turn left on a red light in a diverging diamond interchange if I make a complete stop and the road looks clear?
Buffat told EastIdahoNews.com that drivers cannot turn right or left when the traffic signal has a red arrow. Drivers exiting U.S. Highway 20 planning to turn left have an obstructed view of traffic traveling from the right, so they need to wait for a green light.
Why were both Exit 332 and Exit 333 under construction at the same time?
The Idaho Transportation Department originally planned to construct one exit in the summer of 2024 and the other exit in the following summer. Through public comment, many community members requested the exits be reconstructed in one summer.
“It was great to hear that people were willing to tolerate long-term closures, especially at such busy interchange areas,” Buffat said.
Because of the unique construction schedule, there will be no construction on the exits next year.
Why don’t the construction workers work overnight to finish the exits faster?
Since March, they have been working 12-hour days, six days a week. Rest periods are necessary to ensure the workers’ safety.
“We know it has not been easy trying to travel in and through and out of Rexburg this summer, but we are really confident it is going to be better and it’s very nearly coming to a close,” Buffat said.
Exit 332 is closed for construction through Oct. 4. Once the exit is reopened, the roadway construction will be complete. Exit 333 has one lane open in both directions as construction continues.