Montana Department of Transportation

Public Involvement

MT 21 Bridges (Simms – Augusta)

MT-21 Bridges project logo

Construction FAQs

(MP = milepost)

Replacement of the bridges and decks will require road closures. One two-lane gravel detour will be built at MP 17.9 (Heppler Coulee). Single-lane, gravel detours will be required at some locations:

  • MP 12.0
  • MP 14.5 (Loomis Coulee)
  • MP 17.4
  • MP 0.1 (Elk Creek), MP 0.2 (Elk Creek Overflow) and MP 0.7 (Hogan Slough) (Detours or temporary closures will be determined at a later date.)

One two-lane gravel detour will be built at MP 17.9 (Heppler Coulee).

There are two locations where a detour is cost prohibitive: MP 9.2 (Dry Creek) and MP 19.8 (Simms Creek). These locations will be closed to all vehicles and traffic. The closure of the highway at these locations will occur between July 5 and August 22 of the construction year and one structure will be open to traffic before closing the other. The contractor will be encouraged to replace these bridge decks in less than 35 days. Advance signs will be placed to warn motorists of the detours and closures. Drivers will experience slower speeds on the detours and should allow additional travel time for driving alternate routes during the closure period.