Design-Build Speeds Construction of I-11 Boulder City Bypass
The $318 million, 15-mile long Interstate-11 will bypass Boulder City, Nevada, and provide drivers with an expressway connecting Las Vegas and Phoenix, relieving congestion, improving safety and enhancing commerce.
"Las Vegas and Phoenix are two major metropolitan areas in the country, each with a population of more than 1 million, not connected with an interstate," says Fred Ohene, Deputy General Manager of the Regional Transportation Commission of Southern Nevada (RTC), Planning & Engineering in Las Vegas. "The whole idea behind this project is to improve commerce and the economy."
Ohene explains that in addition to boosting travel and commerce between the two cities, goods arriving at ports in Mexico will eventually be able to travel on the new four-lane expressway as they head north. The new road is anticipated to reduce congestion by 30 minutes on normal travel days and by an hour on holidays and busy weekends. The new road will circle to the south of Boulder City through desert and mountain territory and pass through the Lake Mead Recreational Area.
Funding and Phasing
The project was divided into two phases. Together, the projects are expected to generate 4,000 jobs in the region. Funding for the projects included $249 million in federal funds, $5 million in state funds, and $64 million in Fuel Revenue Indexing funds.
Fisher Sand & Gravel of Tempe, Arizona, is building the first $83 million, 2.5-mile phase for the Nevada Department of Transportation. Work on the design-bid-build project began in May 2015 and is expected to finish in 2018. The company is paving with concrete.
Las Vegas Paving of Las Vegas, Nevada, began work on the $235 million, 12.5-mile design-build phase 2 for the RTC in March 2015 and anticipates finishing the project in fall of 2018. Phase 2 includes construction of 11 bridges, with both concrete and steel girders; requires 5.2 million cubic yards of blasting; 6 million cubic yards of excavation; 1 million gallons of piped-in reclaimed water daily; and placement of 350,000 tons of asphalt pavement. The entire project now has about 3,000 drawings.
RTC opted for the design-build delivery method due to the complexity of the project and the timeline. CA Group of Las Vegas served as Las Vegas Paving's design partner. All members of the team, including design and construction, and Jacobs Engineering and 4Leaf of Las Vegas as the owner's representative, were located in the same building.
"There was a push by the legislature to get this done," Ohene recalls. "Primarily to deal with the congestion and expedite it. It has worked out wonderfully. We couldn't have better partners, and the collaboration is excellent."
Jared Wagstaff, Project Manager for Las Vegas Paving agrees, saying, "If this was not let as design-build, we would barely be constructing now, and we are more than 70 percent complete. The design was in our control. We knew what was coming and could do some work at risk, because we were the designer."
Las Vegas Paving began design in February 2015 and started construction two months later. It began with the box culverts, pioneering roads and fencing to prevent tortoises from entering the right of way, working off 20 drawings. There were no access roads to the site.
"We took a bulldozer and made a pathway through the desert and up the mountains to get a pickup out there," Wagstaff says. "When we came to crossings with culverts, we had to start constructing to get the material across it."
The Environmental Complexity
Multiple factors make construction of phase 2 complex, beginning with the discovery of naturally occurring asbestos (NOA) along the route. Construction could disturb those fibers and cause them to become airborne and a hazard. RTC worked with environmental agencies to come up with a solution and instituted extensive dust control processes and an air-monitoring program to ensure construction did not increase risk to workers or the public. It posts those results monthly on the project's website.
"We have never exceeded the running average threshold," Ohene says. "From what I understand, this is the largest project using this type of monitoring."
For dust control and construction, the RTC arranged to use 1 million gallons per day of reclaimed water from Boulder City's water treatment plant and 250,000 gallons of potable water. Las Vegas Paving had to figure out a way to distribute the water along the length of the project. The company brought in temporary power, created three ponds to hold the water and built distribution facilities up into the Eldorado Mountains. Additionally, the excavated material cannot leave the site. Las Vegas Paving distributed it along the length of the facility.
"Part of the reason we have been successful in mitigating the NOA is the plan," Wagstaff says. "We were able to mitigate the NOA because of the foresight of our facilities."
A 200-foot-deep canyon splits the project into two parts. Las Vegas Paving divided the project in two, with different teams working simultaneously. One team worked from east to west in the national park and the other team from west to east, meeting at the canyon. Once they met at the canyon, they filled it in and are now constructing a reinforced soil slope to support the road.
There were eight rock cuts. The deepest cut was 1,000 feet across and 250 feet down. Blasting took place almost daily for more than a year and a half. Crews worked double shifts, night and day to complete the work.
"We are literally moving mountains," Wagstaff says.
Las Vegas Paving used mining equipment for completion of this job, including three Caterpillar 785 Rock Trucks, 10 Caterpillar 777 Rock Trucks and a Caterpillar 993 Loader.
Several bridges span canyons, including a cast-in-place concrete box girder, steel girder, precast arch bridges, and a concrete portal bridge that goes below grade. There also is a bridge to allow big horn sheep to safely cross above traffic.
One bridge spans 280 feet across. It required a special 600-ton crane to lift the steel girders into place.
At another scenic location, pier columns reach 110-feet down into the steep canyon.
"The terrain was gnarly," Wagstaff reports. "Our guys had to repel to get to the bottom to set up and secure the form work."
Crews needed to learn how to repel to safely get down to the work area. The men were secured to fixed points on the heavy equipment and on the mountain. They had to climb up at the end of the day.
Another challenge was moving the material and maintaining specific grades, Wagstaff says. Las Vegas Paving used GPS automated controlled equipment, purchased for this project. The project was built as a model and loaded into the automated control system. Wagstaff says, it was an investment, but it saved time and money. Ohene praised the precision of the automated grading control system.
Throughout it all, the teams had to work with a variety of governmental agencies at the municipal, state and federal level. RTC required about 40,000 apprentice hours to help train the next generation of construction workers. Already, Las Vegas Paving has reached 50,000 apprentice hours.
"The success of this project is directly attributed to our ability to work together to solve some complex problems in a way that was satisfactory to everyone," Wagstaff concludes.