Winona Bridge, Mississippi River Crossing CMGC
Project Location: Winona, Minnesota
Synopsis of work:
As Winona, Minnesota, residents settle in for a cold, snowy winter, they can still hear the echoes of progress as construction work for the new river crossing continues downtown. Crews will work through the winter to keep pace with the aggressive schedule set for the new bridge that will cross the Mississippi River from Winona to Latsch Island.
The multi-phased project consists of building a new cast-in-place, balanced cantilevered segmental bridge upstream from the current bridge, then rehabilitating the Warren through truss and reconstructing approach spans of the existing structure. The two-bridge solution is a result of MnDOT working with the community to identify three primary goals for the project: keep the river crossing open, minimize financial burden on the city, and open the new bridge as soon as possible.
The existing bridge will remain open for the duration of new bridge construction, and its eligibility for the National Register of Historic Places heavily influenced the decision for its rehabilitation rather than replacement. The new bridge uses a concrete box girder design that is of comparable height and style to visually complement the iconic historic truss of the existing bridge.
With urgency expressed for completion, MnDOT chose Construction Manager/General Contractor (CMGC) procurement for the project. CMGC is an innovative contracting method that engages a construction manager during the design process. Using a phased plan with multiple work packages, CMGC allows new bridge construction to begin while still finalizing design.
With a goal of having the new bridge built by the end of 2016, work packages had to be quickly defined. Meetings held early on were essential to getting the project schedule set. Ames was notified of being selected on December 21, 2013, and on December 30, a conference call was held to discuss the breakdown. MnDOT and Ames agreed to break up the project into four work packages for the new bridge. Within 15 days of the initial telephone conference, a follow-up call and kick-off meeting solidified the plan.
Work package 1 for procurement of H-piling was awarded on May 1, 2014. Work package 2 was awarded on May 15 for dock installation and project access construction. Work package 3 for construction of cofferdams and substructure of the six river piers was awarded on July 30, which included the critical path work for construction of the river piers. Piers had to be built up and out of the water before the anticipated 2015 spring flooding of the Mississippi River to avoid potential schedule delays due to high water.
To maintain progress, Ames crews worked throughout the harsh 2014/2015 winter to complete the two main river piers of the critical path work. Workers were encased 40 feet below the waters surface inside of steel sheet pile cofferdams. Since cofferdams are not watertight, multiple pumps were used 24/7 to dewater during the foundation construction phase and, as temperatures dropped, the pumps had to be kept from freezing. Infiltrating water quickly froze and formed large ice loads, which required dedicated crews to remove the ice from cofferdam walls and waler systems. By the time spring arrived, construction crews had successfully maintained the schedule.
Work package 4 is currently in progress with construction of the substructure and superstructure of the cast-in-place segmental bridges and approaches. Throughout construction, crews work on both the Winona side and the Latsch Island side to meet the aggressive schedule.
Since late fall 2015 and continuing into summer of 2016, crews are working on the CIP segmental portion of the bridge, casting a 16-foot segment on one side of the river piers and then on the other side to balance it. This is known as the balanced cantilever. This side-to-side construction will continue until the deck meets in the middle, 70 feet above the Mississippi River.
The Winona community has witnessed the complexities of construction as the new bridge slowly and methodically rises up from the river. As part of MnDOTs outreach efforts to keep people updated on the projects progress, images from two webcams can be viewed on the MnDOT website. Presentations and Q&A sessions are held and group walking and boat tours of the construction site are offered. There is also an indoor project kiosk located at the Winona County History Center, with an outdoor project kiosk at the Winona Family YMCA.
Community involvement also extends into the bridge design. In the early stages of development, MnDOT worked closely with a Winona Bridge Visual Quality Review Committee to define aesthetics of the new bridge, rehabilitation of the existing bridge, and surrounding areas of the bridge and approach roadways. Together they established guidelines for the new companion bridge and supporting elements that sensitively complement the unique existing structure and context.
The new bridge construction is tracking ahead of schedule with anticipation for it to be open to traffic in early fall 2016. Rehabilitation of the existing bridge is planned for completion in 2019.