Las Vegas motorists lucky not to find cloverleaf at Centennial Bowl interchange

A cloverleaf just wouldn’t do for Nevada’s second-busiest freeway interchange, known as the Centennial Bowl.

Mike from Las Vegas wanted to know whether a cloverleaf would cost less, and be just as efficient, as the towering 2,500-foot-long flyover bridge that will eventually link the westbound 215 Beltway to southbound U.S. Highway 95.

Long before construction on the $47 million project started in August 2015, the Nevada Department of Transportation determined that a cloverleaf design would cost more and reduce speeds for this busy interchange, traveled by 107,500 vehicles daily in northwest Las Vegas.

For those unfamiliar with cloverleafs, traffic entering from a looping onramp must compete in the same lane with vehicles that use the same ramp to exit the freeway, creating a condition known as weaving.

The competing traffic often causes a jam on these interchanges, which resemble the leaves on a four-leaf clover.

The designers of the new Centennial Bowl ramps had considered a cloverleaf, but it “proved undesirable for several reasons,” NDOT spokesman Tony Illia said.

First, building a cloverleaf would have required additional space. That means NDOT would have needed to buy more land, driving up the cost of the project.

Most importantly, a cloverleaf’s tight geometry only allows for a 25 mph speed limit. The ramp under construction is designed to accommodate vehicles traveling 50 mph, Illia said.

Sections of the Centennial Bowl are being reduced to one lane intermittently from now until June 2017. Northbound U.S. Highway 95 is restricted between Craig Road and the Beltway from 8:30 p.m. to 5 a.m. Sunday night to Friday morning. During the same time frame, the southbound U.S. Highway 95 is restricted between Durango Drive and Ann Road.

Part of the Centennial Bowl project opened to commuters in May, when NDOT crews completed a ramp linking northbound U.S. 95 to the eastbound Beltway.

Crews at the Centennial Bowl site are using enough concrete to build a 120-mile sidewalk stretching from Las Vegas to St. George, Utah, Illia said. That’s 5.2 million pounds of concrete just to build the flyover, not including the supporting columns.

The flyover is being crafted in three separate segments with each measuring roughly 860 feet that range from 1.68 million pounds to nearly 1.83 million pounds.

When completed, the Centennial Bowl is expected to become the second-busiest freeway exchange in Nevada, coming in after the Spaghetti Bowl crossing of U.S. Highway 95 and Interstate 15 in downtown Las Vegas.

SUMMERLIN SPEEDS

Construction crews are installing a system of heavy, high-tension steel cables that will line both sides of the median along Summerlin Parkway, aimed at preventing out-of-control drivers from straying off the road.

Those cables will create a springlike effect aimed at supporting the weight of vehicles that stray from the expressway between Buffalo Drive and the 215 Beltway.

The speed limit was reduced to 55 mph during the road work, and Jim from Las Vegas wanted to know whether the change would be permanent.

It turns out the temporary speed limit reduction will be lifted after construction, Las Vegas city spokeswoman Margaret Kurtz said.

The cable barrier will be completed by Thanksgiving, but a second round of work will start around Dec. 1 to improve traffic capacity on westbound Summerlin Parkway, east of Rampart Boulevard, Kurtz said. That project is expected to last about 210 days, so expect to see that 55 mph speed limit enforced on westbound lanes between U.S. Highway 95 and Town Center Boulevard.

HENDERSON SIGNAL

Steve wanted to know if a traffic signal is coming to the intersection of Water Street and Galleria Drive in Henderson.

“This is a huge intersection in front of the Tuscany Village Golf Club,” Steve said in an email sent to the Road Warrior. “With the Cadence housing tract now being built, traffic is getting heavy, especially during the morning and evening rush hours.”

Designs are nearly complete for the traffic signal, and construction is expected to begin within a year, Henderson city spokeswoman Kim Becker said.

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