I-11, An Interstate Highway System Investment
BY AsphaltPro Staff
Paving through a national park, safely handling naturally occurring asbestos and supplying water to a job site in the desert are only a handful of obstacles that had to be overcome to complete the first section of Interstate 11 in southern Nevada.
It’s also the first addition to the United States’ Interstate Highway System since it was deemed complete in 1992.
I-11 will eventually connect Las Vegas and Phoenix, “the country’s two largest metropolitan communities not currently linked by an interstate highway,” according to Nevada Department of Transportation (NDOT) Public Information Officer Tony Illia.
Arizona is working on its own plans to extend I-11 to meet the work Nevada is doing.
Currently, motorists traveling between these two cities make the 4.5-hour journey on U.S. Highway 93. The completion of I-11 will relieve congestion and reduce travel time by at least 30 minutes. It will also improve motorist safety and convenience, by enabling travel at higher speeds without traffic signals.
Not only will I-11 offer an alternative route for the 34,000 vehicles traveling on US-93 each day, but it will also serve the estimated 32 million people expected to take up residence in this region between now and 2030.
I-11 will also play a significant role transporting goods along the CANAMEX Corridor connecting Canada and Mexico through the United States and supporting free trade throughout North America.
Although benefits to the new infrastructure abound, the contractors on the project had a number of challenges to overcome.
Find the Money
The new section of I-11 was determined necessary based on an Environmental Impact study NDOT conducted in 2005. The four-lane freeway would travel from the southern edge of Henderson, Nevada, bypassing Boulder City on its way to the Hoover Dam Bridge.
A chief reason that this segment would be completed first was the need to alleviate congestion on US-93 around Boulder City. According to Las Vegas Paving Project Manager Jared Wagstaff, traffic on US-93 really slowed as it passed through Boulder City, which has its own traffic and three stop lights.
“Having spent three and a half years in that city and dealing with the challenges that came with immense traffic congestion, I completely understand why this project needed to be built,” Wagstaff said. “Not only does it create a corridor to connect Phoenix and Las Vegas, but also to relieve congestion for residents of Boulder City.”
Due to funding concerns and the sources of the funding, the first segment of I-11 was divided into two phases. One phase was managed by NDOT, with Fisher Sand and Gravel, Tempe, Arizona, as the general contractor. The second phase was managed by the Regional Transportation Council of southern Nevada (RTC), whose members include Clark County and the cities of Las Vegas, Henderson, Mesquite, Boulder City and North Las Vegas. The general contractor on that phase was Las Vegas Paving, Las Vegas.
“RTC brought in a big source of the funding [for phase two],” Wagstaff said. “So they wanted to make sure it was managed the way they wanted it.”
RTC’s funding came from revenue collected from a gas tax indexed to inflation over the course of three years. By this measure, the RTC secured $693 million to fund this and more than 220 other high-priority projects in southern Nevada.
Funding for phase one came mostly from federal funds ($68 million), with another $10 million from the RTC and $5 million in state funds. The second phase required $181.2 million in federal funds and $53.8 million from the RTC.
In April of 2015, NDOT and the RTC broke ground on the 15-mile first segment of what will ultimately become a 300-mile addition to the interstate system.
The first phase of the project was a 2.5-mile stretch from Railroad Pass to US-95. The $83 million section included a full diamond interchange with a loop ramp at Railroad Pass, a 600-foot-long flyover bridge from southbound I-11 to US-93 toward Boulder City, and a 360-foot-long bridge reconnecting railroad tracks previously severed by US-93, under which the mainline freeway passes.
According to Fred Ohene, the RTC’s deputy general manager of planning and engineering, the project was divided into phases due to lack of funds to complete the project all at once. “NDOT had already completed the design for the segment between Railroad Pass and US-95,” Ohene said, “and were moving forward to build that segment of the project under a design-bid-build procurement. Fisher Sand and Gravel was selected as the lowest responsible and responsive bid by NDOT.
The second phase of the project was 12.5 miles of interstate from US-95 to US-93, with Las Vegas Paving as the design-build general contractor. This $235 million phase of the project included a northbound climbing lane, a reconfigured interchange at the US-93 and State Route 172 exit, and 11 freeway bridge structures.
Las Vegas Paving was selected based both on qualifications and low bid. “We came in with the lowest price, but the highest technical score, so our approach to the project was the best all around,” Wagstaff said.
They were selected in early 2015 and began construction within three months. “That’s the benefit of design-build,” Wagstaff said, adding that this project required more than 3,000 drawings. “If we had waited until the design was fully completed, we’d only be halfway constructed by now.”
Phase one was opened in sections from August 2017 until May 2018, and phase two was opened in August of 2018.
This particular segment of I-11 traverses a variety of terrain in a very short distance, from flat desert to foothills to the El Dorado Mountains. Las Vegas Paving began its role on the project in the mountains.
The crews blasted every day for more than a year and a half, with construction crews working double shifts, day and night. The deepest cut on the project was 240 feet. The most manpower Las Vegas Paving devoted to this project at any given time was around 200 people, not including subcontractors such as Sanders Blasting.
In addition to the sheer amount of blasting, Las Vegas Paving also had to contend with the existence of naturally occurring asbestos (NOA) along the project corridor. Originally discovered in 2013 by researchers at the University of Nevada Las Vegas, the NOA threatened to shut the project down, Wagstaff said.
“Since NOA was new to us and this area, we hired various experts and laboratories to assist the RTC,” Ohene said. The experts include Tetra Tech Inc., CDM Smith, Kleinfelder Inc. and Earth Safety Dynamics from the owner’s side, and SCS Engineers and Forensics Analytical Laboratories from the contractor’s side.
“Our project was the first project in the state of Nevada required to put forth mitigation efforts to control naturally occurring asbestos,” Wagstaff said. “As a result, we developed the first naturally occurring asbestos management plan in the state that is now used as a template in the state.”
Those mitigation efforts outlined how the material should be handled, tested and placed within the project limits.
NOA monitoring stations were placed around 2,500 feet apart to monitor NOA particles during construction, crews stopped and reduced earthwork operations during high winds, and workers were randomly selected to wear monitors to ensure the air they were breathing was safe.
Test results were posted on the project website on a monthly basis. Of all the results on project personnel, not a single one exceeded the threshold allowed by the Occupational Safety and Health Administration.
Ensuring the project had ample access to water to mitigate dust and asbestos was also a challenge, especially in the desert. Most of the job had no road access and no infrastructure of any kind.
Las Vegas Paving overcame this challenge by establishing its water facilities early on. They worked with Boulder City to purchase the effluent water the city was dumping in the desert. From that, they created a main collection pond and two additional ponds, each capable of holding 2 million gallons of water. From there, they pumped the water up to the El Dorado Mountains 7 miles away.
On average, the crew pulled 1 million gallons of water per day from the ponds and an additional 250,000 from the Boulder City water system.
“It sounds like a lot of water, but we were working around the clock,” Wagstaff said. “Throughout the project, we never received a single dust violation, which is rare on a project like this with so much blasting.”
Manage Material on Site
The presence of NOA also meant that no materials were allowed to leave the job site.
“Every cut we made had to be placed somewhere on the project,” Wagstaff said. They crushed the material on site with a 28×54 Pioneer Jaw as the primary crusher, along with a Metso HP400 as a secondary crusher. Then, the 6 million cubic yards was transported downgrade from the mountains and used to build an elevated freeway atop the desert floor.
For the long hauls, Las Vegas Paving purchased 11 Cat 777 rock trucks with 100-ton capacities and a Cat 993 loader for mining operations. They also brought in three Cat 785 rock trucks with a 150-ton capacity for the portion of the project with the longest haul. They also used a number of 775 rock trucks as needed.
Not only did it turn out that there was much less asbestos in the soil than previously thought, but it also turned out to be high quality material upon which to build the road. “Once it had been crushed, the properties were really conducive to making good, solid roads. It was easy to compact,” Wagstaff said.
However, he added, the aggregate on site was too porous for asphalt production. As a result, all of the asphalt aggregates were produced offsite and hauled in to the project.
All of the asphalt for the second phase was produced with a portable CMI PTD400 counterflow asphalt hot plant set up on the job site. In total, the plant produced around 350,000 tons of asphalt, producing up to 4,500 tons in a single day.
“We were at the plant’s maximum production of 400 tons per hour,” Wagstaff said.
On top of the 16-inch aggregate base, Las Vegas Paving placed three 3-inch lifts of dense graded asphalt and then ¾ of an inch of open graded asphalt mix.
Due to the NOA, Wagstaff said it was important to cover that material as quickly as possible. To do so, the crew placed the first lift, totaling 100,000 tons of asphalt, between October and December of 2016.
The second lift was paved the next May, and the third lift, the fall of 2017. The final lift of open-graded asphalt was paved in May of 2018. The specs of all mixes used were mandated by NDOT.
In total, the project’s two phases required 5.2 million cubic yards of blasting, 8.2 million cubic yards of excavation and 632,000 tons of asphalt.
National Park Preservation
Another unique aspect to this project was that it was paved through a national park.
“You don’t typically build freeways through national parks,” Wagstaff said, adding that it was important that the National Park Service was also satisfied with the project because NPS and the Federal Highway Administration are peer-level. “One doesn’t have authority over the other.”
“We used a collaborative approach with the NPS to make sure we preserved the integrity of the park,” Ohene said. “The NPS was required to provide input on all design concepts and to review and approve final design plans of any segment of the project that went through the park.”
To satisfy the NPS, Las Vegas Paving took great care to make sure the look of the project didn’t detract from the natural environment.
This included cutting the mountains in small increments to minimize teeth marks and ensure the cuts look more natural, using colors in the bridges that blend into the mountain, and signage that didn’t detract from the environment but still met safety requirements. Additionally, the crew harvested the topsoil and native plants before construction, and placed those materials around the finished job.
NPS also harvested existing native plants and seeds before construction that were then replanted after the project had ended, including around 27,000 cacti.
“The idea was to restore the disturbed area as close to its original condition as possible,” Ohene said. In addition to satisfying the appearance requirements of NPS, there were also environmental concerns.
For example, the project passed through a desert tortoise habitat. This required that a fence be put up around the project, and then the crew and a team of biologists searched for tortoises in ¼-mile segments to place them outside of the fence. In total, they moved 64 tortoises.
There were also a number of wildlife crossings on the project for tortoises, kit foxes, coyotes and bighorn sheep to prevent vehicle-animal collisions. In one instance, Wagstaff said that an 8-foot fence guides bighorn sheep to use the wildlife crossings, including a bridge that crosses over the highway.
There are also two all-terrain vehicle crossings under the interstate, as well.
Las Vegas Paving was also responsible for constructing a scenic overlook. That includes room for bus and car parking, educational signage about the area and the habitat, and a metal shade canopy overlooking Lake Mead.
“It’s a spectacular sight,” Wagstaff said. “There are tons of people out there. We spent more time building that than any single bridge”
The project also included a terrazzo mural depicting the Hoover Dam. Many of the design elements of the project are in an art deco style, in reference to the style in which the nearby Hoover Dam was built in the 1930s.
“We, as a country, just don’t construct projects like this anymore,” Wagstaff said. “We haven’t added to the Interstate Highway System since 1992, but we also don’t build through mountains, build bridges over canyons, or have workers rappelling to secure the forms.”
The I-11 project reminds us of an era not only unique for its art deco aesthetic, but also for its attitude. The Hoover Dam was one of many public works projects funded during the Great Depression to create jobs and improve America’s infrastructure.
Despite depressions, recessions, and political non-cooperation, we can rebuild America if we establish funding, work together, and overcome any obstacle.
The completion of the first segment of I-11 is proof of that.