West of the Nevada-California border, motorists driving on Interstate 15 must travel through the famed Mountain Pass area of California, which is a stretch of more than 12-mi. (19.3 km) of freeway with an elevation change of nearly 3,000 ft. (914.4 m).
In March 2008, a $91 million I-15 Mountain Pass reconstruction project began, which included adding a truck-descending lane northbound, replacing the existing southbound truck-climbing lane with new concrete pavement, and widening and repaving all existing lanes and medians.
The I-15 reconstruction is expected to be completed by fall 2010. The project will improve traffic flow and safety, extend the life of the freeway by 20 years, and provide shoulders and medians for emergency vehicles, said Rose Melgoza, public information officer of Caltrans District 8, adding 50,000 vehicles utilize the Mountain Pass portion of I-15 daily.
Las Vegas Paving is the prime contractor.
“We are turning a dilapidated asphalt road into torque resistant, concrete pavement,” said Jim Witt, project manager of Las Vegas Paving, adding when the project is finished more than 228,000 tons (206,800 t) of asphalt will have been placed and more than 167,400 cu. yds. (128,000 cu m) of roadway excavation completed.
After nearly a year of construction, Las Vegas Paving has completed all median widening construction and bridgework with a crew of up to 70 workers.
Additionally, crews worked on three flat bridges that are on grade but travel over existing flood washes through the mountain pass region. Las Vegas Paving widened each of the bridges by drilling new caissons with a hoe ram and installing falsework, so that concrete could be poured for the bridges’ decks and tier columns.
“We didn’t have to drive pile, but we had to drive down into the rock,” Witt said, explaining the hoe ram drilled between 20 and 30 ft. (6 and 9 m) deep.
Additionally, Las Vegas Paving worked on all bridge over-crossings, which received pavement profile adjustments, along with improved lighting conditions and the rehabilitation of local interchange ramps.
The contractor used graders, heavy-haul trucks, scrapers and pavers for median widening.
The I-15 reconstruction also widened freeway shoulders and added another northbound lane in a mountainous region with tall hills.
As a result, crews blasted more than 90,250 cu. yds. (69,000 cu m) of rock from December 2008 until February 2009.
The blasting took place mainly along the southbound shoulder and was conducted by subcontractor Sanders Construction Inc.
Witt said Sanders drilled numerous holes into the various rock hills and packed the holes with an ammonium nitrate product.
“We chose to use blasting because of the tall mountains of solid rock and the fact that they were at different locations through this section of Interstate-15,” Witt explained.
Once blasted, the pieces of rock were ground down by mobile grinding machines and onsite crushing plants. The material from the blasts was then reused as aggregate base.
It was during this two-month rock blasting period that the contractors involved experienced their greatest project challenges. I-15 southbound had to be shut down to traffic.
Initially, Witt said the blasting plan was going to involve more than 80 different blasts that would take place over the course of four months. This would mean a significant amount of highway closures.
However, in a cooperative effort with the Nevada Department of Transportation, the Nevada Highway Patrol, the California Highway Patrol, the Las Vegas Convention and Visitors authority, and Primm Properties, Caltrans and Las Vegas Paving developed a plan to close the highway on the Nevada side at Primm for 4 hours on Wednesdays from 10 a.m. to 2:00 p.m.
“This project has had minimal impacts because of the public relations and media advisories,” Witt said. “It’s been a great partnership where we’ve all been committed to getting this done efficiently.”
By concentrating the blasts to only Wednesdays, the contractors were able to blast multiple locations and larger areas to accelerate the removal of the rock.
This reduced the closures down to just eight, Melgoza said, adding it was determined, based on lowest traffic flow and the inability to conduct blasting at night, that mid-day Wednesday was the best time for blasting and highway closures to occur.
The last blast occurred on January 11, despite some project shutdowns due to snow.
Because the mountain pass region is environmentally and biologically sensitive, Caltrans and the contractors involved also were constantly monitoring for wildlife, such as the desert tortoise, while blasting and when conducting other project work.
Currently, Las Vegas Paving is excavating the southbound outside truck lane in preparation for the laying of new concrete pavement. This portion of the project will continue for the next three months, Melgoza said.
One feature Caltrans and Las Vegas Paving implemented to accommodate the large volume of vehicle traffic during this portion of construction was to build an express lane for the southbound traffic.
This express lane will eventually become the new northbound lane, which will enable trucks to descend the hill safely and avoid runaway danger.
Originally the southbound shoulder construction limited southbound travel to just two lanes for 9 months.
Following the rehabilitation of the southbound truck lane, Las Vegas Paving will complete all shoulder widening work during the summer, which will include extending and rehabilitating the existing drainage system, and adding guardrails and transition railings.
Once all shoulder and lane widening is complete the contractors will remove and replace 6 in. (15 cm) of concrete on the remaining lanes in both directions and complete the northbound truck lane, Witt said, adding the project remains on schedule.
Melgoza confirmed this statement, adding there are no funding issues associated with the project. Recently some Caltrans roadway projects have been delayed due to state funding issues.
In addition to Sander Construction Inc., other subcontractors on the project included: Moore Electrical Contracting, Marina Landscape, AC Dike Company, Knight & Levitt and Associates, Resources & Soil Tech, FCI Constructors Inc, DJ Scheffler Inc, Pacific Coast Steel, Diversified Concrete Cutting, Desert Empire Drilling and Harber Companies.
Material suppliers included: Sam’s Equipment and Supplies, Universal Industrial Sales, Hanes Company, Pacific Corrugated Pipe and Supply, and Interstate Sales. CEG
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