Dresbach Bridge On Track For Completion
SEGMENTS, SPRING 2016, VOL. 60
The new Interstate 90 Dresbach Bridge over the Mississippi River will be a highly utilized river crossing serving as a gateway for regional and interstate needs and an enhanced local connection for the adjacent communities. The replacement I-90 Bridge connects La Crescent, Minnesota, and La Crosse, Wisconsin, and is currently finishing construction, addressing a significant Minnesota DOT need, and bringing great mobility benefit to the area.
A new, modern, and ecologically-conscious four-lane concrete bridge is replacing the existing deficient structure. Over the main channel of the Mississippi River, the new 4-span bridge features twin, cast-in-place post tensioned segmental concrete structures with 508’ main spans, built from above with form travelers in balanced cantilever. Building from above eliminated the need for large ground and water based equipment and allowed commercial and recreational river traffic to continue throughout the duration of construction unimpeded, and with minimal environmental impacts. Construction is kept to the smallest footprint to protect the environment, adjacent recreational facilities, and USCOE Lock and Dam No. 7 just upstream.
One hundred-foot-long sheet piling was used for the nearly 80-foot-tall cofferdams needed to install the main-span unit foundations. Large pedestals and twin wall piers are founded on 42" diameter pipe piling and are designed to resist accidental vessel collision. Despite spring flooding and difficult Minnesota winter conditions within the first 12 months of construction, Ames was able to construct all of the piers but one within the first two construction seasons. Casting rates of four segments per week were typical for the eastbound bridge, while the westbound bridge frequently had a production rate of six segments per week.
All segmental cantilever construction has been completed for both the eastbound and westbound bridges. The bottom slab, webs, and end diaphragm for the 45-foot long cast-in-place section of Span 1 westbound has been cast and currently the top slab forming operations are underway. Once the top slab is cast and post-tensioning operations are completed for the end span cast on falsework, crews will focus on casting the last two closure segments in Spans 1 and 2 westbound, followed by miscellaneous finishing operations. The eastbound bridge was opened to traffic on November 13, 2015 and the westbound bridge is on track for early completion.