How much does Gurley Overpass get used?

As one of only two grade-separated railroad crossings in the city, the overpass serves as a critical access point between and north and south sides of the community. It is estimated that there are approximately 10,000 vehicle crossings made over the structure each day.

Why is Gurley Overpass closed twice a year?

Since 2019, the City has conducted annual inspections of Gurley Overpass. Generally, the overpass is closed for five to ten days in the late spring for the inspection work. Information from the inspection period determines what annual maintenance is required. Later in the summer, the overpass is closed for one to two weeks for annual maintenance and repairs. 

The annual inspection and repair process is helping to extend the safe and useful life of the structure.  A summary of inspection and maintenance expenditures over the last ten years can be found here.

If Gurley Overpass is being regularly inspected and maintained, does it really need to be replaced?

Annual inspections over the last five years have consistently identified delamination of the deck as a significant issue with the condition of Gurley Overpass. Delamination occurs when moisture reacts with and corrodes the rebar in concrete. The rebar expands and separates the top and bottom layers of concrete. 

To mitigate the effects of delamination, preventative annual maintenance of Gurley Overpass for the last several years has largely consisted of epoxy deck injection repairs. In short, holes are drilled into the top layer of concrete on the deck where delamination has been identified. Epoxy is then injected through the holes into the areas of delamination.

This maintenance has extended the life of Gurley Overpass, but delamination will continue to affect the deck. The Gurley Avenue Overpass Structural Condition Review published by Structural Dynamics, LLC in October 2023 states:

“[W]e currently project that the Gurley Overpass deck will remain serviceable through 2026 with reasonable (not annual) preventative maintenance performed on the deck, and potentially longer if annual preventative maintenance is performed. However, we still continue to advise the City of Gillette have plans for a replacement structure prepared and ready to construct starting in Spring 2027.”

Have other locations for a railroad crossing been considered?

Yes, the 2021 Planning Study by HDR analyzed eight conceptual crossing locations and then provided further evaluation of the three highest-ranked locations, as follows:

• A new overpass at Butler-Spaeth Road

• A replacement overpass at Gurley Avenue

• A replacement consisting of two redundant one-way structures at Gurley Avenue

The recommended location is replacement with a single structure at the current Gurley Avenue location. It meets the City's travel forecast demand for future population growth, while maintaining a central location and connections to other important north-south transportation corridors.

Has the City been saving money for this project?

Yes, The City has been setting funds aside for the future replacement of the overpass, with $7,000,000 currently allocated for the project.

In addition, the project was awarded $3,000,000 in federal funds as part of the FY23 Omnibus Appropriations Package.

How much will it cost to replace the existing structure?

The 2021 Planning Study identified a total project cost of $30,000,000. Based on recent inflation trends and construction anticipated to begin in 2028, the City estimates the total project cost at $40,000,000.  

Why are we planning for an overpass with four lanes?

Planning level recommendations include a four-lane structure to accommodate future growth and to mitigate traffic interruptions. During the design phase of the project, evaluations will be completed to determine the number of lanes that will best serve the community.

For some inspection and maintenance operations, two lanes of a four-lane structure can be closed at a time, while the other two remain open to two-way traffic. Construction may also allow continued traffic crossings during phased construction of the new structure. The existing structure can remain open to traffic while half of the width of the new structure is built. Once traffic is diverted to the completed portion of the new structure, the existing structure would be demolished while the second half is built. 

What other improvements will be incorporated in the design of the replacement overpass?

Design recommendations for the replacement overpass include dedicated space for pedestrian and bicycle traffic. In addition, the new structure will be shorter in length with less grade to reduce the winter traction issues caused by the steep approach grades of the current overpass.

The project will also include replacement and widening of Gurley Avenue on either side of the bridge from 6th Street to Warlow Drive, extension of 6th Street to 7th Street from Gurley Avenue to Butler Spaeth, stormwater system improvements, utility relocations, and right-of-way and easement acquisition.