Besides local commuters, traffic in the area includes 18-wheelers and oil field traffic with large loads. The 2014 incident was not the first time the structure got hit by vehicles attempting to drive under it.
However, the 2014 incident was more serious. WYDOT reviewed the structure and determined it would need to be reconstructed. Among the changes was a rise in the clearance from 16 feet to 19.6 feet. During this time, the city of Rock Springs approached WYDOT as they were looking to increase connectivity and accessibility.
This involves doing roadwork to connect the interchange to a service road. They are extending the road a few hundred feet to tie into an existing road. “The city wanted to connect the two service roads to the interstate,” says Stephanie Harsha, a Public Relations Specialist for WYDOT.
The scope of the project grew to include three structures. First, it will replace the existing bridge over the interstate to provide a higher vertical clearance, and construction of eastbound and westbound ramps with continuous acceleration/deceleration lanes. Second, the project includes building a new grade-separated 390 feet crossing over the Union Pacific Railroad for access to the industrial park. Finally, the team is widening a bridge over a creek to make it the same width as the new roadway.
There are other constraints around the project area, including a water treatment plant on one side and another side has industrial buildings. Plus, there are utilities, including fiber optic lines along the railroad that the team has to work around.
The WYDOT bridge department collaborated with geologists and created a plan to build the embankment in three stages of 10 feet at a time. “After each stage, we wait a minimum of 50 days to monitor settlement and determine if we felt the ground was stabilized,” says McCullough. “We did it in stages to ensure the material compressed all the way.” He reports that there has been no rebound, and the foundation is solid.
There have been soil issues around the interstate bridge as well. The team used extended drill shafts to get into solid material and get friction. The team used a segmented drill rig. In normal drilling operations, you usually have one casing for an entire drill shaft. This rig operation utilized 4 to 10-foot sections to get to the proper depth. This resolved some of the issues with the soil conditions.
Although this is not necessarily unusual machinery, it is uncommon to this area. The segmented casing and the machinery that comes with it – the drill and the drilled shaft – is atypical. Most drilled shafts in the area are not this deep or constructed with the unique soil conditions here.
The work, while necessary, led to other concerns about what to do with interstate traffic while the bridge was down.
“We made sure to complete the on and off ramps to the interchange before we took down the old structure. We did this because we needed to be able to keep traffic moving on this highly traveled interstate route. We were able to put interstate traffic on the on and off ramps while we removed the structure. That way, we didn’t have to close that section of the interstate while we were working,” says Peter Stinchcomb, a District Construction Engineer for WYDOT.
Why did WYDOT apply for the grant? Harsha explains.
“WYDOT applied for the grant to help improve traffic flow and safety in the area,” says Harsha. “Currently, there is no direct access to the interstate from the industrial area. Trucks have to drive through residential areas to access the industrial park. With I-80 being a major freight network, the new interchange will help improve movement of freight within the state and nationally, helping to diversify the economy in this part of the state. It can also help entice future growth in the industrial area by offering direct access to the interstate.”
The project, including design, has a budget of $26.6 million. Other monies came from the city and county and standard federal funds.
While there have been some change orders, the team expects the project to be within the contingency.
Reiman & High Country Construction Joint Venture Limited Partnership is serving as the general contractor on the project. Stinchcomb, who has worked with both outfits in the past, says, “Reiman is a bridge specialist, and High Country excels at excavation work, so they make a good team for this project. They’ve been good at planning and are good at looking ahead.” He adds that the team did portions of the project offsite to speed up the process.
Construction began in the spring of 2021 and is scheduled for completion in June 2023. At this point, McCullough expects the interstate portion to be completed on schedule. However, the new grade-separated crossing over the Union Pacific Railroad is behind schedule. He pointed to the soil issues and communications with the railroad as the reasons for the delays.
“The other sections of work did not have issues with the extreme soil conditions and were already built to a point; crews are basically adding to existing infrastructure. The interstate structure already had an embankment, and the roads were all existing and just needed to be widened,” Stinchcomb said.
When the project is complete, the area will enjoy increased connectivity and an opportunity for greater development in an underused part of the town.