Trimble Technology Creates Digital Model, Proper Grade on 24-mile Interstate Project

Trimble survey equipment, software and grade control combine on the 24-mile, 35-month I-15 construction project resulting in quality, efficient and safe road work

In building the road, the contractor first laid an average of 1 ft. of select granular borrow or crushed stone aggregate then a half of a foot of smaller, open graded base was placed on top.
In building the road, the contractor first laid an average of 1 ft. of select granular borrow or crushed stone aggregate then a half of a foot of smaller, open graded base was placed on top.

The Challenge:

Expand and reconstruction 24 miles of I-15 in Utah - an equivalent of 435 lane miles - within a 35 month time frame

The Players:

Utah Department of Transportation
Fluor Company
Ames Construction Company
Ralph L. Wadsworth Construction Company
Wadsworth Brothers Construction Company

The Process:

The project is the expansion and reconstruction of 24 miles of I-15 in Utah - the equivalent of 435 lane miles. Included in the job are 66 lane miles of cross-street improvements, the rebuilds or replacements of 10 interchanges, 63 new or modified bridges, 12 temporary bridges, retaining and noise walls, and all the drainage/utility/electrical support for the finished interstate road.

Here's a quick look at some quantity numbers on the billion-dollar project:

  • Roadway excavation = 2,000,000 cubic yards
  • Aggregates / sand = 9,000,000 tons
  • Concrete paving = 2,800,000 square yards
  • Asphalt paving = 3,750,000 square yards
  • Structural steel = 12,000,000 tons

The Utah County I-15 Corridor Expansion (I-15 CORE) project began in April 2010 and had a deadline for an end of 2012 completion - an unprecedented 35 month schedule. The Utah Department of Transportation (UDOT) selected a joint venture company, called Provo River Constructors (PRC), to design and build the I-15 CORE. PRC is led by Fluor Company, Dallas; Ames Construction Company, Minneapolis, Minn.; Ralph L. Wadsworth Construction Company, Draper, Utah; Wadsworth Brothers Construction Company, Draper; and includes at least 30 other subcontractors.

“This design-build project is massive, requires 1,500 workers, and we’re using the latest technology throughout,” said Scott MacKenzie, survey manager for PRC. “We probably have the largest number of Trimble systems in use at one jobsite in the world.”

“We’re using Trimble survey equipment to collect site data, Trimble software to create the site plan digital model, Trimble GCS900 Grade Control Systems on all of our blades and dozers, and Trimble PCS900 Paving Control Systems for all the finished paving,” said Jarred Rico, assistant survey manager for PRC. “The technology is invaluable on a project like this. We’re more efficient, productive and managing a safer worksite.”

According to the PRC managers, the technology is helping them stay ahead of schedule. “Our crews are working 24/7 to meet the tight schedule we have,” MacKenzie said. “There is no good manual way to accomplish everything we’re doing on this project."

PRC built the digital model from all of the jobsite and design data collected at the site.

“Fortunately, the Trimble technology allows us to build and adjust the digital model as we progress along the 24-mile route,” MacKenzie said. “We encounter soil changes, differing community standards from city to city and a lot of conditions that weren’t on the plans, so we have to survey and send the changes into the model builders for the most current plan that we work from.”

Over the years much of the existing road had been resurfaced multiple times. They wouldn’t use a profile, but would mill an inch or so off the existing road and then add a lift of fresh asphalt. This road is heavily used so UDOT determined that I-15 needed to be reconstructed and widened. When completed, the freeway will have up to six travel lanes in each direction, plus on-ramps and exit lanes. The inside and outside shoulders will be generous concrete-paved emergency shoulders.

Laying the road

In building the road, PRC first laid an average of one foot of select granular borrow or crushed stone aggregate, which needed to be imported to the site. Then a half of a foot of smaller, open graded base was placed on top. Since the subbase had been graded with a motor grader using a Trimble GCS900 Grade Control System, PRC felt confident it could accurately place the gravel layers.

On top of the gravel subbases, PRC then placed a 3-inch layer of a lean mixture of hot mix asphalt (HMA) using a pair of pavers equipped with Trimble PCS900 Paving Control Systems to pave 24-foot-wide strips.

“Because we used Trimble PCS900 paving systems on the asphalt base, we not only ensured that we used the proper amount of HMA, but we also saved on concrete yields because the concrete use is a direct reflection of the thickness, quality and consistency of the asphalt,” Rico said. “Not having to use wire line, just for starters, saves a lot of labor, accidents and rewiring. Plus, there’s a higher level of confidence using the technology.”

Using the Trimble systems also allowed PRC to monitor and document its progress. The company checked its work every 10 feet to ensure quality.

“Our production is faster and our end-result quality is better,” MacKenzie said. “As long as the system and paver are running right and we maintain the confirmation checks, we can complete whole sections and not have to do any grinds.”

The project calls for placing anywhere from 10.5 to 12.5 inches of concrete. UDOT required PRC to stand behind the wearability of this heavily-traveled road. PRC will be issuing a four-year-warranty.

Communication is key

With a massive and complex project such as I-15 CORE, communication is critical. Errors not only can be costly, but they can eat up time.

“We’re using the Trimble Connected Community, which is a web-based service that allows us to communicate in real time with our people and machines on the site,” Rico said. “I can literally sit at a desk somewhere and make changes to the digital site plan and send it out to everyone on the site. It eliminates the cost and time of driving out to the jobsite and locating every rod, total station and machine to plug in a change.”

“I-15 CORE is a custom design project so there are changes and adjustments that need to be made at all times,” MacKenzie said. “It would be a nightmare to have to function without the Connected Community - when you think of manually trying to get changes out to 80-some GPS machine systems and data collectors on the site, we wouldn’t be as far along as we are.”

“My number one concern all along is safety,“ MacKenzie said. “The project has been very safe and being able to use the automation that Trimble provides helps keep workers off the grade and out of harm’s way.”

“Also,” Rico added, “when you look at the volume of information collected, processed and relied on every day, we wouldn’t be able to produce the level of quality as quickly as we have without the help of technology.”

Jeff Winke is a business and construction writer based in Milwaukee, Wis. He can be reached through