Crews Anchor Rims Rocks to Prevent Falls Near Homes
A three-week closure of Zimmerman Trail will block a major route for 13,000 daily drivers while engineers secure a 70-foot rock shelf above the road.
By Sanjay Caldwell ·
The city of Billings is closing Zimmerman Trail for three weeks to stabilize a section of cliffside that engineers say poses a risk to vehicles and nearby residences. The closure takes effect immediately and is expected to last until late November, cutting off a direct connection between the West End and the Heights neighborhoods. More than 13,000 drivers use this route on an average day, making it a critical artery for local commuters and businesses.
Public Works project manager Will Robbins stated that the work is centered on an S-shaped curve near the slow down sign at the top of the Rims. The goal is to prevent rocks from falling onto the roadway or into the houses situated below. This preventive measure follows a year-long assessment conducted by the engineering firm TerraCon. The firm identified a rock segment approximately 70 linear feet wide showing signs of undermining and stress cracking. These conditions indicate that the rock shelf could detach, potentially causing damage to the road and structures underneath.
The city bid out the project in September. Robbins explained that while engineers cannot predict exactly when the unstable segment might shift, they determined it has the highest potential for movement of any section in that area. This uncertainty is the primary driver for the intervention. The repair process involves drilling into the rock face to a depth of about 20 feet. Workers will install steel anchors and use grout to secure them in place. They will then attach plates to the front of the rock face to hold the segments together.
The crews will drill past a crack believed to exist behind the loose segment, anchoring the work into solid bedrock for added stability. As an additional safety measure, they will apply shotcrete and cable to the surface. Robbins described the cable system as a backup suspension mechanism designed to catch any falling debris. Finally, the team will cover the repaired area with dyed shotcrete to match the color of the surrounding cliff, making the repairs visually blend into the landscape.
The three-week timeline was selected to provide the contractor with maximum flexibility while ensuring the safety of workers and the public. Robbins noted that the schedule is driven by contractor availability, though there is a possibility the work could finish earlier than planned. The city is using the closure to complete other maintenance tasks that would otherwise require separate road closures. These additional repairs include fixing a guardrail that has sustained damage from vehicle impacts and conducting geotechnical drilling for a future project that Robbins said he cannot yet detail.
Local residents and business owners face immediate disruptions due to the detour. Sam Brewer, an employee at Ace Hardware Boutique who lives in the Shepherd neighborhood, expressed concern about the added travel time. He noted that his commute, which typically ends at 5:00 p.m., requires him to pick up his son by 6:00 p.m. The detour threatens to make him late for family obligations. Brewer predicted that many drivers will not fully understand the impact of the closure until it begins, particularly regarding increased traffic volume on alternate routes.
Amy Piercy, who also works at the boutique, said the shop relies heavily on customers who drive down Zimmerman Trail from the Heights. She anticipated that the closure would reduce the number of impulse visits from drivers passing by. However, she acknowledged that the city advertised the closure well in advance, allowing frequent users to plan alternative routes. Despite the early notice, local workers and shoppers are preparing for a period of congestion and reduced foot traffic in the area.
The stabilization project represents a proactive step in managing the geological risks inherent to the Rims. By securing the 70-foot rock segment now, the city aims to avoid a more urgent and potentially more disruptive repair in the future. The combination of steel anchors, grout, and cable systems is intended to provide long-term stability to the cliffside. The closure will remain in effect until the contractor completes the anchoring and finishes the cosmetic shotcrete work.
