A project on a major corridor in South Dakota’s largest city, the I-29 and 12th Street Interchange in Sioux Falls, presented challenges not only in handling traffic but in smoothly accelerating an overly ambitious project, one that could easily have been divided into two years.
The project includes rebuilding one and one-half miles of I-29 to flow over West 12th Street. As part of the reconstruction, West 12th Street was widened from Lyons Boulevard through Marion Road, adding additional through lanes and a left turn lane, as well as center medians. Crews also rebuilt the West 12th Street/Marion Road intersection in addition to 1,500 ft. of Marion Road.
In addition, the project included grading, curb and gutter, storm sewer, sanitary sewer, water main replacement, roadway lighting, signals, permanent signing, pavement marking and PCC pavement.
“Twelfth Street went from two lanes in each direction to three lanes in each direction plus outside turn lanes and inside median turn lanes,” Brad Benson, project manager of Upper Plains Contracting in Aberdeen, S.D., explained. “So if you look straight across we now have nine lanes.”
South Dakota Department of Transportation (SDDOT) obtained a piece of land to accommodate the additional lanes wide enough to make an access for a right-of-way. However, Benson said, in order to keep the roadway as narrow as possible, retaining walls were built, which became an alternative to widening the roadbed area by cutting down the 6 to 8 ft. of elevation change west of the bridge.
“Those Type C retaining walls have footings extending into a sidewalk and a stamped wall that will be painted a prairie rose color with the coping on top a buffed tan color,” Benson said.
Increased business development spurred the need to widen the corridor, which resulted in increased traffic. “Those heading out of town use it and it is a main artery in town,” Bensons said.
To allow continuous traffic flow, a temporary bridge was installed over I-29 during one of the initial stages of the project. This made it possible to remove a bridge over 12th Street, which is a major corridor in Sioux Falls, Smith added. The two-lane bridge allowed I-29 traffic flow for West 12th Street.
I-29 and West 12th Street remained open for the majority of the project.
Temporary roads were also built along the interstate to keep traffic moving. Those temporary roads will now be removed, Craig Smith, area engineer of SDDOT, said.
Construction crews closed the northbound 12th Street onramp throughout construction. The northbound onramp was closed approximately one month after construction began and traffic was detoured to the 26th Street and Madison Street interchanges.
Excessive rain could have been a factor during Midwest summers but a dry 2006 season aided in the acceleration of the project, Smith said. A dry fall made it possible for work to proceed as planned.
The finishing touches should be part of the 2007 season and completed on time.
Construction on portions of the project, such as 12th Street west of I-29, was actually ahead of schedule during July, “which allowed us to get a jump start on constructing the westbound lanes of 12th Street,” Benson said. I-29 traffic was switched from the existing southbound lanes to the new northbound lanes in early August.
“To accomplish the lofty goal, from a DOT standpoint, we put a lot of effort into finding ways to accelerate the project and to allow traffic,” Smith said. “We strived to have the sequence we put together in the plan carried through to the actual construction.”
“We didn’t think about the amount of work, we just did it,” Benson added. “I want to thank the subcontractors for accelerating the project to achieve greater results than what the plans showed; it could have been a two-year project. I can’t express my thanks enough.”
The project required about 35,000 truck loads of imported borrow and another 7,500 truck loads of gravel, Benson said. For the deck pours on the 12th Street bridges, over 600 yards of concrete were needed for each pour, which took a full day.
“We had two concrete pumps going continuously but it still took between 8 and 16 hours for each pour,” Benson said.
Utilities presented some of the largest challenges during the project, “mostly on 12th Street once we got into the westbound lanes,” Benson said. “There were a lot of unknowns from when it was designed on paper to when it was built to when it was opened,” Benson said. “The department [DOT] had a well organized consulting engineer firm they worked with who was there at every beckon call to expedite things and to make changes without many delays. Sometimes we would have three or four changes at one time. For 30-40 days were many changes, mostly with communications.”
Currently, traffic is still being handled expertly so finishing touches can be completed. Work is proceeding in a median curve so traffic has to be switched.
“Traffic is now head to head,” Benson said. “We need to split the traffic to the east and west bound lanes so we can get to the middle portion and button up the project and complete the colored concrete. Then, once we’re done with the concrete in the middle, we will switch the traffic to the middle and work on the outside lanes.”
By the end of November, bridges were being painted along with the bend, which are columns for the center structure of bridge, Benson explained. Traffic control on the bridges and on the intersections of Marion and Ebenezer had also been activated.
The new roadway was opened on schedule Nov. 3, allowing for traffic to travel in both directions. The overall completion date for the 12th Street/I-29 Interchange project is expected June 29, 2007. But the project’s interim completion date was Nov. 3, 2006, in which the contractor must have had all lanes of Interstate 29, Marion Road and 12th Street completed and opened to traffic.
“Southbound I-29 will have a completed surface and completed barrier walls,” Benson said. “Temporary surfacing to tie the bridges to the main line and some temporary barriers helped expedite the project. The crews were motivated so we got the final surface and barrier walls on; next year that will be taken off to supplement the new surface.”
Inconvenience to the general public should be minimal in 2007, he added. Benson noted that illumination on 12th Street is better.
“This fall we plan to finish the color concrete, the median, sidewalks on the south side so the public can walk through safely under the bridge and won’t have to trip through mud in spring,” Benson said.
Any unfinished sidewalks, modular walls, color stamping, curb restoration, sod and pavement markings should be completed by 2007. CEG