Highway 43 - Chief Joseph Pass to Wise River project logo

October 2023

The design is currently underway. Construction is expected to occur in 2026, depending on completion of design and availability of funds. The main Elk Creek Bridge, the Elk Creek Overflow (currently three culverts), and Hogan Slough structures will be replaced.

May 12, 2021

Construction is complete from the 2020 project. This year, design is underway to address Milepost 0.1 Elk Creek, Milepost 0.2 Elk Creek Overflow, and Milepost 0.7 Hogan Slough. Floodplain modeling and the preliminary hydraulics report have been completed. The main Elk Creek Bridge and the Elk Creek Overflow (currently 3 culverts) will be replaced with new two-span concrete bridges. Final recommendations for bridge size are expected soon and the road alignment and bridge locations will be set.

August 13, 2020

Chip sealing has occurred on various areas between MP 9 and 20 (Dry Creek to Simms Creek).

Temporary lane striping will be in place until it is replaced with permanent epoxy striping. Permanent striping isn’t expected until mid to late September. Seeding will occur off the roadway in October. Both operations of striping and seeding will have very little impact to traffic.

What is permanent striping? To define the lanes and shoulders, permanent striping will be a two-part epoxy. This is extremely durable, thick, and reflective. It requires a special spray truck that can measure and heat the components while mixing and applying them.

Text updates are also available. Text "MT21Bridges" to 47177.

Please feel free to let us know if you have questions by calling our project hotline at 888-275-9840 or by contacting Laura

August 7, 2020

MT 21 between Simms and Augusta will be chip sealed early next week. Loose gravel will be present until it is swept up by the following day. Drivers can expect reduced speeds until sweeping is completed. Other work this week includes removing the two-lane detour at Heppler creek, installing guardrail ends, placing topsoil and fencing.

Why do you chip seal? And how? Chip sealing can extend the life of the roadway. It provides a moisture barrier by sealing cracks and increases its ability to flex without breaking. The process includes first applying liquid asphalt, then a layer of asphalt coated chipped rock. A roller is used to press the rock into the liquid asphalt. The embedded rock protects the liquid seal and improves traction.

Text updates are also available. Text "MT21Bridges" to 47177.

Please feel free to let us know if you have questions by calling our project hotline at 888-275-9840 or by contacting Laura

July 28, 2020

MT 21 between Simms and Augusta is now open. The closure that was at milepost 20, Simms Creek, is now open to all traffic. The Simms Creek bridge has been replaced and paved. Work continues between milepost 9-20 and gravel surfaces and brief one-lane detours may be present.

View the closure map here.

Text updates are also available. Text "MT21Bridges" to 555888.

Please feel free to let us know if you have questions by calling our project hotline at 888-275-9840 or by contacting Laura

Road Closed at Dry Creek. Bridge decking under construction.

Road Closed at Dry Creek. Bridge decking under construction.
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Road closed to all traffic.

Road closed to all traffic.
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July 23, 2020

MT 21 between Simms and Augusta is currently closed to all traffic at milepost 20 (Simms Creek) and no longer closed at milepost 9 (Dry Creek). The closure is expected to last to the end of July. Simms Creek is about 1.5 miles west of Simms. Crews are widening and replacing the bridge deck over Simms Creek. Drivers should plan additional travel time for alternative routes. Areas of gravel should be paved by the end of next week. Even if workers are not present at Simms Creek, the road is still closed to all traffic. Please continue to obey traffic signage.

View the closure map.

What’s a bridge deck? The bridge decking installed at Dry Creek and Simms Creek is a corrugated metal surface that will be paved over. This decking strengthens the bridge for heavy loads and provides a good surface for pavement.

Text updates are also available. Text "MT21Bridges" to 555888.

Please feel free to let us know if you have questions by calling our project hotline at 888-275-9840 or by contacting Laura

Road Closed at Dry Creek. Bridge decking under construction.

Road Closed at Dry Creek. Bridge decking under construction.
Click on the image for a larger view

Road closed to all traffic.

Road closed to all traffic.
Click on the image for a larger view

July 14, 2020

MT 21 between Simms and Augusta is currently closed at milepost 9 (Dry Creek) but the closure will move to milepost 20 (Simms Creek) July 15th about midday. Simms Creek is about 1.5 miles east of Simms. The closure is expected to last about 2 weeks. Only one closure will be active at a time, so Dry Creek will open before Simms Creek closes. Crews are widening and replacing the bridge deck over Simms Creek. Drivers should plan additional travel time for alternative routes.

View the closure map here.

Until Simms Creek is closed, it will be down to one lane during the day which is managed by a flagger and traffic light. Some of the gravel areas between milepost 9-20 will be paved in the next week.

Text updates are also available. Text "MT21Bridges" to 555888.

Please feel free to let us know if you have questions by calling our project hotline at 888-275-9840 or by contacting Laura

Road Closed at Dry Creek. Bridge decking under construction.

Road Closed at Dry Creek. Bridge decking under construction.
Click on the image for a larger view

Road closed to all traffic.

Road closed to all traffic.
Click on the image for a larger view

July 10, 2020

MT 21 between Simms and Augusta is currently closed at milepost 9 (Dry Creek) which is about 11 miles east of Augusta. Crews are widening and replacing the bridge deck. The closure will move 10 miles east to Simms Creek in approximately the next week or two. Drivers should plan additional travel time for alternative routes. Once that closure is completed and opened, the second closure at Simms Creek will begin. It is also expected to take about 2-3 weeks.

View the closure map here.

Simms Creek at milepost 20 is down to one lane only during the day which is managed by a flagger and traffic light. There are some unpaved surfaces between milepost 9-20.

Text updates are also available. Text "MT21Bridges" to 555888.

Please feel free to let us know if you have questions by calling our project hotline at 888-275-9840 or by contacting Laura

Road Closed at Dry Creek. Bridge decking under construction.

Road Closed at Dry Creek. Bridge decking under construction.
Click on the image for a larger view

July 2, 2020

Starting Monday, July 6th the Montana Highway 21 (MT 21) will be completely closed to traffic at MP 9 (Dry Creek). The closure will last about two to three weeks. Drivers should plan additional travel time for alternative routes. Once that closure is completed and opened, the second closure at Simms Creek will begin. It is also expected to take about 2-3 weeks.

Construction will also be active in various locations between MP 12-19 as crews works towards placing new pavement. Day-time single lane closures are expected in a few of these areas but the delays should be very brief. Subscribe for updates, text "MT21Bridges" to 555888.

Happy 4th of July! Construction will stop over the weekend beginning around noon on Thursday July 2nd. It will resume Monday July 6th with the start of the road closure. Have a fun and safe holiday weekend!

Text updates are also available. Text "MT21Bridges" to 555888.

Please feel free to let us know if you have questions by calling our project hotline at 888-275-9840 or by contacting Laura

June 24, 2020

Work continues between milepost 9-20. Drivers can expect areas of gravel road surfaces and speed limits reduced to 25-35 MPH near these areas. Brief one-lane detours may be present during the day but should only result in very brief delays.

Text updates are also available. Text "MT21Bridges" to 555888.

Please feel free to let us know if you have questions by calling our project hotline at 888-275-9840 or by contacting Laura

June 18, 2020

Work is intermittent between milepost 9-20. Drivers can expect areas of gravel road surfaces and speed limits reduced to 25-35 MPH near these areas. Brief one-lane detours may be present but should only result in very brief delays.

Next week: paving in two locations between milepost 12-18.

Text updates are also available. Text "MT21Bridges" to 555888.

Please feel free to let us know if you have questions by calling our project hotline at 888-275-9840 or by contacting Laura

6.5.2020 MP 18 Decking

6.5.2020 MP 18 Decking.
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June 11, 2020

Work is intermittent between milepost 9-20. Drivers can expect areas of gravel road surfaces and speed limits reduced to 25-35 MPH near these areas. Brief one-lane detours may be present but should only result in very brief delays. Crews are currently working on guardrails at some of the bridge locations. Motorcyclists should exercise caution in these areas.

Text updates are also available. Text "MT21Bridges" to 555888.

Please feel free to let us know if you have questions by calling our project hotline at 888-275-9840 or by contacting Laura

Gravel road surface image

Gravel road surface.
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June 3, 2020

Two brief detours between MP 17-18. Speed limits are reduced to 25-35 mph near the detours. A few gravel surfaces between MP 12-15. Motorcyclists should take extra care in these areas. All detour lanes are 11 feet wide. Wider loads should use an alternate route.

Road Closure Expected Timeline: The first road closure at Dry Creek is still scheduled for early July, after the holiday. The closure is expected to last about 2 weeks. Once that closure is completed and opened, the second closure at Simms Creek will begin. It is also expected to take about 2 weeks.

Text updates are also available. Text "MT21Bridges" to 555888.

Please feel free to let us know if you have questions by calling our project hotline at 888-275-9840 or by contacting Laura

MP 17.4 One-lane detour and temporary traffic signal image

Click on the image for a larger view

May 28, 2020

Five brief detours between MP 12 and Simms Creek. These are managed by flaggers and temporary traffic signals. Expect very brief delays. Speed limits are reduced to 25-35 mph near the detours. All detour lanes are 11 feet wide. Wider loads should use an alternate route.

Road Closure Schedule Update: The first road closure at Dry Creek is still scheduled for early July, after the holiday. The closure is expected to last about 2 weeks. Once that closure is completed and opened, the second closure at Simms Creek will begin. It is also expected to take about 2 weeks.

MP 17.4 One-lane detour and temporary traffic signal image

Two-lane detour, looking east.
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May 21, 2020

Four single-lane detours are at MP 9.2, 14.5, 17.4, and Simms Creek. These are managed by flaggers and temporary traffic signals. Expect very brief delays. A two-lane detour is at MP 17.9. Speed limits are reduced to 25-35 mph near the detours. All detour lanes are 11 feet wide. Wider loads should use an alternate route.

MP 17.4 One-lane detour and temporary traffic signal image

MP 17.4 One-lane detour and temporary traffic signal.
Click on the image for a larger view

May 14, 2020

A new single-lane detour will be established at milepost 9.2 (Dry Creek). The two other single-lane detours are still active at MP 12 and 14.5 as crews install culverts. These detours are managed by flaggers and traffic signals. Drivers can expect brief delays. A two-lane detour is still active at milepost 17.4 (Heppler Coulee). All detour lanes are 11 feet wide. Wider loads should use an alternate route. There is no longer a traffic impact at MP 4.25 (Bickle-Burke).

MP 14.5 Culvert being placed and single-lane detour on the right.

MP 14.5 Culvert being placed and single-lane detour on the right.

May 7, 2020

Two new one-lane detours will be established before the end of this week at MP 12 and 14.5 (Loomis Coulee) They are managed by flaggers and traffic signals. Expect brief delays. The two-lane detour at MP 17.9 (Heppler Coulee) is still active while bridge reconstruction is underway. The box culvert extension at MP 4.25 (Bickle Burke) will be wrapping up this week.

MP 17.9 Heppler Coulee Bridge Deck Removal

MP 17.9 Heppler Coulee Bridge Deck Removal

April 30, 2020

Along MT-21, the two-lane detour at MP 17.9 (Heppler Creek) is established. Next week, additional one-lane detours may be active. Detour lanes are 11 feet wide. Wider loads should consider an alternate route. Work is ongoing at MP 4.2 (Bickle-Burke). Minor delays expected.

Culvert extension work at MP 4.2 (Bickle-Burke)

Culvert extension work at MP 4.2 (Bickle-Burke)

Two-lane detour at MP 17.9 (Heppler Creek)

Two-lane detour at MP 17.9 (Heppler Creek)

April 22, 2020

There are a few sections of state highway 21 between Simms and Augusta where drivers will experience one-way traffic. Flaggers and temporary traffic signals will be directing the traffic flow. Drivers will experience brief delays. These patterns will remain in place until the detours are constructed. At milepost 17.9 Heppler Creek, there will be a two-lane detour established near the end of April. Detour lanes will be 11 feet wide and wide loads should consider an alternate route.

At milepost 4.2 Bickel Burke Ditch, drivers may experience brief slowdowns.

Detour under construction at milepost 17.9 Heppler Coulee

Detour under construction at milepost 17.9 Heppler Coulee