Perma bridge improvements to begin

Construction on a project to rehabilitate the bridge at Highways 382 and 200 in Perma will begin later this month. Montana Department of Transportation (MDT) held public meetings last week to inform residents and stakeholders about the project.

The 635-foot bridge on Highway 382 was built in the 1960s. Brandon Graff, alternative contracting engineer with MDT, said that construction will begin as early as July 24. He noted that the amount of wear and tear on the bridge is normal for one that age, and that the bridge is still safe for travel. "The project will extend the service life of the bridge," Graff said during a public meeting last Thursday.

Included in the Perma bridge project are improvements including painting some portions of the steel structure to prevent rust and corrosion, milling the top layer of the concrete and putting a new layer on the driving surface, as well as paving the approach at both ends of the bridge. New guardrails will be installed across the bridge and on both approaches. "We're bringing those safety features up to more modern standards," said Beth Kappes with Morrison Maierle, the designer of the project.

One aspect of the project is to replace bearings and repair damage to steel girders. This will entail using large jacks to lift the bridge off the substructure to replace the bearings, said Kappes. The new bearings are made of rubber instead of metal. "They are much more robust to weathering and the elements," Kappes explained. However, replacing the bearings will also mean a complete closure of the bridge. The complete closure will likely take place the last weekend in July or the first weekend in August, said Kris Anderson with Frontier West, the contractor who will be completing the work. During that time, alternate routes will be needed. Throughout the remainder of the project, travelers will see single-lane closures on the bridge. Anderson said the construction this fall will continue 6-8 weeks into mid-October, and in spring 2024 will continue with the painting of the structure and the final pavement work.

Kappes expressed that while the main portion of the Perma bridge project is aimed at rehabilitation, there will also be some safety improvements. For example, rumble strips will be installed between the bridge and the intersection of the two highways. She said that Frontier West will employ hydro milling to remove the top layer of concrete. Using high pressure water helps reduce the risk of damaging the reinforcement on the bridge deck, she noted.

Darrell Williams with MDT said the agency's bridge bureau manages more than 4,500 public bridges in the state. Graff also noted that MDT will work with local first responders to ensure that services are uninterrupted. For updates on the bridge project, text PERMA to 866-434-0866 or go to mdt.mt.gov/pubinvolve/permabridge. The state website 511mt.net also has the latest road information.