Originally completed in 1928, the Champ Clark Bridge--so named for a former Missouri Speaker of the House--stood as a landmark along the Mississippi River for nearly a century. But like all man-made creations, its serviceable life eventually and inevitably came to an end—and a new alternative was required.
The bridge linked Louisiana, Missouri, an area of rolling hills that feature quite a lot of agricultural development, with Pittsfield, Illinois, where the soils are classically rich river bottom soils, ideal for farming. Its replacement structure now carries the same burden of community connection. What was once just 20 ft wide, with extremely narrow 10-foot shoulderless travel lanes now boasts a pair of 12-foot driving lanes and 10-foot shoulders in each direction, more than doubling the traversable width. For a rural area that has farming equipment as a regular part of the overall traffic mix, this improvement has been long overdue.
Due to the length of the cross-river spans, designers opted for steel girders over precast concrete, though precast did come into play elsewhere in the project. “It made more sense to use steel on the river spans,” Terrence J. Colombatto, project manager for contractor Massman Construction Company, told Roads & Bridges. “The spans range from 260 feet to 420 feet in this area, and had we chosen concrete on those spans, we would have had to shorten the spans or go with a post-tensioned spliced concrete girder. We also would not have been able, likely, to reduce the piers in the river. But we did use precast on the approach spans. There are three approach spans we used concrete girders on.”
With any river construction there is always the risk of flooding, and crews did experience the second highest recorded river flow in the Mississippi’s history this past summer. It was something Massman had to perpetually contend with; however, the reduction in the number of in-river piers did make the river work somewhat less difficult than it might otherwise have been.
“We were able to eliminate one of the piers,” Colombatto said. “The old bridge had five in the river, we have four, which was nice as it reduced the impact of displaced water and flow, and helped us achieve the no-rise criteria that was set by the U.S. Army Corps of Engineers.”
Massman used large, 11-foot-diameter drilled shafts in the piers, which enabled a reduction in the number of shafts per pier and aided the project from a cost-savings perspective. It was one of several means Massman employed to optimize and improve the project timeline.
Another cost and time saver was using precast deck panels. Designer HNTB Corp. had used precast deck panels before on other projects; the benefit to the Champ Clark Bridge project was to keep it on schedule. A total of 181 precast deck panels were used in the construction of the new bridge. Each deck panel was 46 feet wide, extending to the full width of the bridge.