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MDT: I‑90 speed limits appropriate; crash clusters near Bear Mountain and Drummond flagged for targeted safety work
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Summary
Montana Department of Transportation told Granite County commissioners its I‑90 speed study found operating speeds consistent with posted 80 mph limits and did not recommend lowering speeds; MDT identified two crash clusters and urged targeted signage, delineation and operational fixes instead of a blanket speed reduction.
Joel Bushey, a project development engineer with the Montana Department of Transportation's Missoula District, presented the results of an MDT speed study for Interstate 90 between roughly mileposts 139.7 and 157, telling the Granite County Board of Commissioners that measured 85th‑percentile speeds averaged about 82.1 mph and that the study does not recommend reductions to the posted 80‑mph limit.
Bushey said crash analyses for 01/04/2020–12/31/2024 showed 289 reported crashes in the study area, including four fatal crashes and 18 suspected serious injuries. Two crash concentration areas were identified: near reference posts about 144.3–145.3 and between roughly 153.8–154.8. Fixed‑object collisions and run‑out crashes were the most common types, and more than half of crashes were reported on snow, ice, frost or slush‑covered surfaces.
"Operating speeds along the corridor were generally consistent with the existing posted speed limit," Bushey said, summarizing MDT's analysis and telling commissioners the tool MDT uses (National Cooperative Highway Research procedures) balances measured speeds, crash history, roadway geometry and context.
Local residents and elected officials pressed MDT on options beyond speed changes. Blake Bradshaw, a local resident, said many crashes result from drivers traveling "too fast for conditions," especially in canyon and winter conditions, and asked whether flashing signs or additional treatments could be added. Bushey said the study found that targeted signing, improved delineation and limited geometric or operational improvements are likely to be more effective safety approaches than lowering the posted speed across the corridor, and noted that funding is competitive.
Bushey also flagged that average daily traffic (ADT) ranges in the corridor vary seasonally: MDT's 2024 figures were roughly 8,800–13,200 vehicles per day between interchanges, with weekday and peak summer volumes exceeding 20,000 vehicles in some locations. He recommended further targeted safety projects for the crash clusters and said MDT would pursue benefit‑cost analyses to seek state safety funding where justified.
Commissioners and members of the public asked MDT to consider additional warning signage, flashing lights and portable devices near the most hazardous stretches; Bushey said MDT would coordinate options with local agencies and towns, but cautioned that many safety remedies require project nomination and state funding prioritization. The study also references Montana code on interstate speed maxima and the state's procedures for setting limits.
The county will accept written comments on the study during the 60‑day comment window the presenter established and MDT said comments not received within 120 days will be regarded as concurrence with the speed study.
