Diverging Diamond in the Rough


Henderson drivers will soon find themselves on the wrong side of the road—intentionally, safely and briefly—in a diverging diamond interchange at West Horizon Drive and U.S. 95. The first of its kind in Southern Nevada, the interchange, which is scheduled to begin construction later this month, will guide vehicles onto the left side of the overpass bridge to access the freeway more easily.

“It sounds so weird,” Henderson Public Works engineer Scott Jarvis says. “But the beauty of it is, since you are on the wrong side of the road, when you need to make a left-hand turn to get on the freeway, there are no cars coming the opposite direction, so it’s a free left.”

With four traffic signals 1,500 feet apart, the interchange built in 1991 is among Henderson’s most congested, Jarvis says, with more than 18,500 vehicles using the northbound U.S. 95 ramp daily, an increase of 5,200 vehicles a day since 2005. The city paid $453,000 to traffic-engineering consultant CA Group for computer modeling, traffic analysis and design.

The diverging diamond concept was noted as one of the top engineering innovations of 2009 by Popular Science when it was introduced in Springfield, Missouri, and currently there are nearly 40 in the country. Until now, though, the nearest one was in St. George, which opened Utah’s fifth last year. (There also has been a diverging diamond in Reno at Interstate 580 and Moana Lane since November 2012.)

An animated video from CA Group will soon be posted on the city’s website to alleviate any motorists’ concerns that signs, striping, barriers and lights will not be enough to properly direct them. “When most people hear of the diverging diamond interchange, it sounds a little confusing,” Jarvis says. “I have driven through several of them, and I have to tell you, it’s very anticlimactic.”

Construction on the $2.6 million project is expected to take less than five months, with most lane closures scheduled during nighttime hours.

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