Second phase of 41st Street diverging diamond to begin Monday

The South Dakota DOT urges drivers to put distractions away as the construction, which resumes March 27, could occasionally see lane changes throughout the day.

A diverging diamond is meant to increase traffic safety and efficiency by having traffic drive on the opposite side of the road, eliminating the need for left turns. Crews are currently constructing one at 41st Street and Interstate 29 in Sioux Falls.
Contributed / South Dakota Department of Transportation

SIOUX FALLS — Phase two of construction on the 41st Street diverging diamond project is set to resume Monday, March 27, bringing lane closures to the Interstate 29 overpass along one of the Sioux Falls’ busiest stretches of roads.

Construction is set to resume Monday morning on the south side of the 41st Street bridge, with traffic being restricted to one eastbound and one westbound lane. A center lane will be used for left-turning vehicles to access Interstate 29 on-ramps.

South Dakota Department of Transportation (SDDOT) Project Engineer Kirk Henderson told Sioux Falls Live that Monday’s lane reduction is expected to remain in place until roughly the end of summer, but noted that which lanes will be in use could change quickly.

“Sometimes you can drive through a construction project and it could seem like the same thing over and over again, but this year I’m sure we’ll be moving around,” Henderson said. “You could be driving in one lane in the morning and then they could flip-flop traffic and by the afternoon you’re driving in a different lane.”

Lane reductions during this year’s work won’t be unique to 41st Street, either, with Henderson adding that closures should be expected along Interstate 29, too.


Phase two of 41st Street's diverging diamond construction is set to resume Monday, March 27. This map shows the status of the project as of Tuesday, March 21, 2023.
Contributed / South Dakota Department of Transportation

“On Monday, the northbound driving lane [of I-29] — which would be the far-east lane — will have a lane closure, and then periodically there will be lane closures in the northbound and southbound lanes as they’re building the bridge,” Henderson said.

In an effort to reduce impacts to traffic, Henderson indicated that the SDDOT is planning overnight closures to all lanes along I-29. Depending on which side of the interstate construction crews will need access to, traffic would be rerouted to the opposite side of the highway from approximately 7 p.m. until 6:30 a.m. Decisions on which Interstate lanes would be closed and when have not yet been made.

Sioux Falls Public Works Department is urging drivers to plan for delays and to slow down.

As work begins to wrap up on the bridge, construction crews will shift their focus toward expanding the rest of 41st Street between Terry Avenue and Empire Place.

Monday’s start date marks the beginning of the second phase of the diverging diamond implementation, which is intended to create a safer and quicker experience on 41st Street. With a diverging diamond, drivers switch which side of the road they normally use to eliminate the need for a left turn. The project is more than a decade in the making.

Phase one, completed in 2022, saw the expansion of 41st Street between Terry Avenue and Marion Road to the west of the overpass, as well as a reconstruction of the 41st and Marion intersection.

Henderson said that while phase two is expected to be completed this year, the “flip” of traffic won’t go into effect until the third — and final — phase in early 2024, when crews will be adding finishing touches to the intersection.

With lots of changes coming, Henderson made clear that drivers need to pay attention to ensure the safety of themselves, construction crews and other drivers.

“Safety is the main message I’d stress to motorists,” Henderson said. “We want everyone to get home safely and get to their destination safely with minimal disruption.”


A South Dakota native, Hunter joined Forum Communications Company as a reporter for the Mitchell (S.D.) Republic in June 2021 and now works as a digital reporter for Forum News Service, focusing on local news in Sioux Falls. He also writes regional news spanning across the Dakotas, Minnesota and Wisconsin.
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