It won’t be an Interstate highway, but Highway 100 might see a comparable amount of traffic once the project is fully complete.  

Slowly the project has been forming into shape with the planned route starting on the north end near Exit 402 on I-90 to Exit 73 where it meets I-29.  The next phase of the project will be completing the connection from Highway 42 to I-90.  If all goes according to plan, the work will begin going north of Arrowhead Parkway in 2015 and linked to I-90 by 2019.

First the route has to be finalized.  South Dakota Secretary of Transportation Darrin Bergquist says one final hurdle ground is broken.  “This ultimately needs approval by the Federal Highway Administration.  We have already gone through the environmental process (with this proposed route).  Once (the Federal Highway Administration) signs off, then this will be considered the final route.”

Bergquist explains multiple factors will shape why the road will shift to the east from Madison Street to Rice Street.  “That happens mainly for topography and constructability reasons.  We’re able to avoid some residential areas by doing that.  The flatter you can build your road, the safer it’s going to be due to improved sight distances.”  It’s also a cost factor because level means cheaper.

Speaking of cost, Highway 100 will have to cross the Big Sioux River.  Bridges add cost to any highway project.  “There’s going to be an awful big structure to get across the river.”  However as recently as 8 years ago, a proposal to shift the project farther east was floated because of the river.  “In the 2006 to 2007 time frame we started looking at some options on that northern piece to shift everything to the east.  One of the big reasons for that was the size of the structure that might be needed to go over the Big Sioux River.”  Going farther east would have shortened the necessary bridge by 500 feet leading to substantial savings.  Since then Bergquist believes the DOT can utilize the original route and build a shorter bridge which will assist from a cost standpoint.

Once fully complete, an estimated 35,000 vehicles per day are projected to use Highway 100 which compares to current traffic numbers on I-229.