NewBridgeWillKeepTwoTownsFromSeasonalDisconnect

In addition to the two-way traffic configuration, a 10-ft. width restriction will be in effect around the same time. Overwidth vehicles will be directed around the Oahe DamutilizingS.D.Highway1806, S.D. Highway 204 and S.D. Highway 1804. The width restriction will remain in place through theentire2023constructionseason.

VanDeWiele stressed that river traffic will remain open during the entire construction process.

“Recreation on the Missouri River is not only important to the residents of Pierre and Fort Pierre, but also people from across the state and tourists. Jensen Construction Company, the prime contractor, has developed a river traffic control plan to keep boats awayfromtheworkzoneandkeep the public and construction employees safe.

“Jensen Construction Company is a heavy highway contractor with a primary emphasis on bridge construction. Jensen has more than 100 years of experience ranging in services from bridge construction, railroads, wind tower foundation and marine work. Jensen has completed jobs throughout the central United States with work primarily inthepublicsector,andiscommitted to building quality, design-bidbuild projects that will exceed expectations and be done in a safe and efficient manner.”

There are, however, numerous challenges on the project.

“The river fluctuates up and down approximately four feet every day,” said VanDeWiele. “Also,thecurrentbridgeisonly10 feet away from construction of the new bridge, resulting in limited space to build the roadway on the ends of the bridge.”

Crews are currently focused on erecting the structural steel girders and constructing the Fort Pierreside abutment. Intersection work will soon start at the Highway 14/83 junction, as well as work on the mechanically stabilizing earth retaining walls for the Pierre-side abutment.

Twelve drilled shafts have already been constructed, and considerableworkhasbeenperformed on the Pierre-side abutment. In addition, six bridge bents have been built, which includes columns, capitals, caps and pedestals.

An oversized steel casing, 13.5 ft.indiameter,wasinstalledfroma floating barge down through the water into the river bottom. A permanent 10-ft. diameter steel casing was installed inside the oversized casing and allowed for the concrete to be placed inside the 10-ft. casing, eliminating concerns about fresh concrete being spilled into the river. “The permanent casings were approximately 49 feet long,” said VanDeWiele. “They were installed into the bed of the river and turned intothe shale,creating a solid foundation.

“The ‘shaft’ was then excavated using an auger to drill deep intotheshalebelowtheriver’sbottom. This occurred in a two-step auguring process. Once the shaft wasexcavatedandcleanedout,the steel reinforcing rebar was inserted into the drilled shaft. These cages were fabricated offshore and taken by barge and lowered into the drilled shaft using a crane on the barge.Specialspacerswereusedto make sure the rebar didn’t come into contact with the bottom or sides of the drilled shaft to ensure the rebar was completely encased by the concrete.”

Upon final inspection of the placement of the rebar, concrete was then placed in the drilled shaft.Aconcretepumpwasusedto fill the drilled shafts with concrete. Thiswascarriedoutbydisplacing the water in the drilled shaft with concrete using a tremie tube, a long pipe with a length greater than the depth of the drilled shaft.

“Oneendofthetremiewaslowered to the bottom of the drilled shaft, and concrete was placed through the use of the tremie tube,” said VanDeWiele. “Before starting to place the concrete, a foam ball was inserted into the top end of the tremie tube. Once the ball was in place, concrete was placed in the tremie tube abovetheball.Bytheweightofthe concrete on top of the ball, the ball was pushed down the tremie tube which acted as a squeegee pushing the water down and out the bottom of the tremie.

“When the ball exited the tremie’s bottom, the concrete then quicklybegantodisplacethewater in the bottom of the shaft in an upward direction. The tremie remained embedded into the concrete by five feet or more and was liftedatthesameratethatthe concrete came up in the shaft until the tremie reached the top of the permanent casing.”

“Following the placement of the six haunch girders over the bent seven cap, crews have been working on the six span girders at the Pierre-side abutment. The first two span girders for the Pierre abutment were lowered from atop the current bridge using cranes. The remaining four girders were lifted from a trailer on the ground of the Pierre side of the project. Once each span girder at the abutment was lined up with the corresponding haunch girder over the bent seven cap, they were connected using a splice plate and highstrength bolts.”

Numerous testing procedures were used throughout the process to guarantee the highest quality in materials and to ensure the installation was correct. Each drilled shaft contains approximately 365 cu. yds. of concrete and nearly 65,000 lbs. of steel. The concrete obtained a strength of more than 4,500 lbs. per square inch.

VanDeWiele noted that a large amountofrockpileshadtobebuilt during construction. More than 1,100 18-in. diameter aggregate columnswereplacedundereachof thebermfootprintstohelpstabilize the soils and prevent settlement where the berms meet the structure. In review of the project soils, SDDOT geotechnical engineers implemented the aggregate columns into the design.

Regarding girder erection for the new Pierre-Fort Pierre Bridge, VanDeWiele said it’s starting to stretch across the Missouri River.

“Work on the structural steel begantheweekofMarch13,2023.

The six haunch girders were trucked to Pierre/Fort Pierre and lowered from atop the current bridge utilizing two cranes on barges and one along the Pierreside shoreline. The girders were lowered onto the temporary ‘angel wing’ support on the bent seven cap, secured and braced.

As far as excavation, with only 10 ft. of space between the two bridges, the new roadway alignment merges into the old alignment. Therefore, excavation is complicated by the need to construct the new alignment immediately adjacent to the old. Construction sequencing is being done such that traffic can be maintained and funneled through the construction area.

Approximately 36,355 cu. yds. of unclassified excavation and 34,267 cu. yds. of contractor-furnished borrow will be moved duringconstruction.Heavyequipment at the site has included multiple cranes, barges and excavators. Main materials include concrete, reinforcing steel, steel pile, structural steel and rock.

It’s anticipated the new bridge will be open in the summer of 2024. Removing the existing bridge and plaza work under each abutment will then follow.

“In order to build a structure of this magnitude, there’s a tremendous amount of communication, meetings and logistical discussions between SDDOT, contractor, designers, industry suppliers and experts, along with local governments and the Federal Highway Administration,” said VanDeWiele, who added it’s rewarding to see work continuing on such an important project.

“Asthepublicisnowabletosee the work being completed above the water, there is a general excitementwatchingthisprojectcometo fruition. Every week brings a change. This will be further enhanced with 2023 grading, paving, signal work and bridge deck construction.”  CEG