Located in Central Wyoming, Casper is on the North Platte River and saw its population grow during the pandemic when many people chose to relocate to less populated and lower cost areas. Wyoming Department of Transportation (WYDOT) is in the middle of a project to help traffic continue to flow safely and smoothly on Interstate 25 (I-25) through Casper to serve commuters and freight operators.Parallel two-lane bridges known as the Walsh Drive Bridge were constructed in 1968 and the box girder concrete bridges have been rated structurally deficient for several years.

Over the past few years, WYDOT has been forced to spend increasing maintenance time and dollars to keep the bridges operating as needed. Dealing with expansion joints, water retention issues and surface patching during the areas short maintenance window made maintaining the bridges more difficult.

“We considered replacing the deck but there were other issues and ultimately decided it was better to build a new bridge,” says Mark Williams, a District Construction Engineer with WYDOT.

The bridges are critical for both residents and beyond. It serves as an important freight route, as truck traffic is nearly 15% of the total ADT of 18,300. Locals also use the Walsh Drive Bridge to travel from the east to the west side of Casper.

The old bridges were demolished in August 2021. The new bridge will be a single structural steel plate girder bridge. The bridge is composed of approximately 3.5 million pounds of structural steel and will have nine girders all the way across.

The replacement bridges will be approximately 850 feet long, which is 300 feet shorter than the previous bridges. WYDOT is also replacing the overpass with one, shorter bridge structure. Designing a smaller deck was intentional. “Reducing the deck size makes maintenance easier – easier to maintain pavement than a bridge,” says Williams. “System wide deck condition is one of the metrics we use to measure ourselves."

To get proper clearance where girders are integral, the team used straddle bents. This allowed them to minimize vertical alignment variations on the interstate while maximizing clearance underneath the structure.

Wyoming is known for its cold weather, but WYDOT and area contractors find ways to work around the weather wherever and whenever possible.

To keep the project moving and on schedule, the team had to put down concrete during winter months. They used concrete heaters and blankets to keep the materials at suitable temperatures and were able to get the job done.

On a project such as this one, WYDOT typically moves traffic to one bridge, while replacing the other. Once the new bridge is up, traffic would flow on it, while the second new bridge is being built. However, on this project, the team built an offsite detour adjacent to the existing bridge. “This allowed us to do bridge work in the winter without worrying about traffic,” said Williams.

A second area challenge - the bridges span an old railroad bed that is now a part of the City of Casper’s Rails to Trails system as a multi-use path. While the tracks are not currently in use, the Rails to Trails agreement requires the replacement structures to be designed to be able to accommodate a future railroad track if it was needed.

As with many projects around the country, the team also dealt with supply chain issues. “Getting steel has been a problem,” said Rob Wise, a Project Manager with Ames Construction, the general contractor on the job. The team had to make seven-plus trips to the fabricator in Billings, Montana to ensure the delivery of the steel. Normally, a few phone calls would suffice.

“Eventually, we got what was needed,” says Wise. The team needed to engage in creative scheduling to keep work moving forward. “We shifted things around to make sure delays have been minimized.”

This was Ames's first job in the immediate area, but they have worked with WYDOT previously. Williams has been impressed. “Ames created a good schedule and plan of attack and been diligent about moving things forward,” says Williams.

Justin Clark, Chief Inspector/Senior Engineer, for WYDOT said, “One thing about Ames that has really impressed me is they have different crews for each task. Often, we see contractors throw the same guys at everything rather than having crews specialize in certain tasks.”

The project has a $29.7 budget. Financing is being handled via the traditional 80/20 split between the federal and state governments.

Besides a few change orders, the team has managed to keep the project on track due to forward thinking. Ames ordered the materials during the early days of the project. “We did lots of ordering in the first six months of the project, so we would have the material on hand when we needed it,” says Wise. It also enabled Ames to lock in prices and avoid the current inflated prices.

The project began in June of 2021 and is scheduled to complete in June 2023 as planned. Despite the delays in steel delivery, the team has kept the project moving forward.

The team expects to have the bridge opened to traffic by the end of 2022. In the spring, the crew will remove the detour and do some finishes. There’s a small side project going on that is focusing on landscaping and signage that will also take place then.

Photos Courtesy of WYDOT