The Spaghetti Bowl Gets a New Look
By Tony Illia

Southern Nevada's population boom has left its highways hemorrhaging, unable to keep pace with 8,000 people per month moving into the area, but a new "Spaghetti Bowl" interchange hopes to change all of that.

Washington Group International Inc. of Boise, Idaho, is currently building the $82.2 million, Interstate-215/515 interchange in Henderson. A recent U.S. Census Bureau report names Henderson as the country's third- fastest- growing city in the country with a 17.3 percent population increase from April 2000 to July 2002.

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Washington Group's A+B contract calls for the construction of eight new bridges-four concrete and four steel-plus the widening of three bridges and 2 mi. of new six-lane concrete freeway.

The bridge structures will be set atop drilled shaft foundations and supported by a total of 240 reinforced concrete columns with the largest measuring 9 -ft. -sq. in size.

Ready Mix Inc. of North Las Vegas will supply a total of 150,000 cu. yds of concrete for the project. Century Steel Inc., of Las Vegas is providing the reinforcing steel and Utah Pacific Bridge & Steel of Salt Lake City is supplying the structural steel while Las Vegas Paving Corp. is doing the paving.

Washington is self-performing the concrete and earthwork.

Like the gambling state itself, the project has potentially big payoffs and equally as big losses, with $20,000-a-day liquidated damages after 470 working days, and $20,000-a-day in early completion bonuses up to $1.2 million.

"We'll have at least 150 people and 30 subcontractors working on the job during the height of construction activity," said John Kantz, Washington Group's project manager.
"The work is pretty straight forward, but due to the traffic mitigation, it becomes more difficult. The entire project is structured so that traffic disruptions are kept to a minimum."

Designed by Parsons Brinckerhoff Inc. of New York, the same firm responsible for neighboring Las Vegas's Interstate-15/U.S. 95 "Spaghetti Bowl," the Henderson interchange will try to adequately anticipate the region's explosive growth.

When the $93 million I-15/U.S. 95 interchange opened in April 2000, some ramps met their 20-year traffic projections within months.

The Road Information Program and U.S. Census Bureau report that traffic in the Las Vegas Valley increased by 82 percent, between 1990 and 2000.

"The [traffic] projections on the Las Vegas Valley have tended to be on the lower side of the scale than what is being met," said R. Scott Rawlins, the Nevada Department of Transportation's project manager. "But nobody can predict the future of this valley."

Currently, the interchange's busiest section sees 73,000 vehicles daily, but it will be capable of handling up to 180,000 daily motorists once completed.

"The interchange design has built-in capacity to expand if needed," said John P. Clark, Parson Brinckerhoff's supervising engineer. "The ramps are wide enough to go from one to two travel lanes with only new striping being added."

The multi-phased job is a complex one, consisting of about 1,500 sheets of plan -drawings. The job includes a new bridge over a railroad line and the realignment of two electrical transmission towers onto a roadway median.

Additionally, the contractor must erect a 2,500-ft.-long, 60-ft.-tall steel bridge over two new bridge structures plus install storm drainage. All of this must be done while keeping two travel lanes continually open or pay penalties of $500 for every 15 minutes of shut-down.

The new interchange is scheduled to open by summer 2006.

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