WisDOT implements ABC techniques

Madison, Wis. — A bridge currently being built on Interstate 39 over Siggelkow Rd. near Madison is the first on the I-39 corridor to utilize Accelerated Bridge Construction (ABC) techniques. WisDOT has begun implementing ABC methods for bridge construction in Wisconsin, in accordance with the Federal Highway Administration’s (FHWA) Every Day Counts initiative.

Part of the I-39 expansion between Madison and the Illinois border, the Siggelkow Road bridge project involves widening the road bed, demolishing the old bridge, and building a new two-span structure using precast elements. The new bridge will be 14 feet wider to accommodate the increased traffic capacity.

The use of prefabricated concrete bridge elements such as prestressed girders, pier caps and pier columns is a principal ABC method. Constructing these elements off site can save weeks or even months of construction time by eliminating on-site forming, rebar tying and concrete curing. According to WisDOT, “Prefabricated elements are (also) often of higher quality than conventional field-constructed elements, because the concrete is cast and cured in a controlled environment.”

County Materials Corporation supplied the prestressed and precast elements for the Siggelkow Road bridge project. These include 20, 45W girders (each 110 feet to 116 feet long); five 16-foot, 5-inch-tall, 3-foot, 6-inch by 4-foot pier columns; and two 39-foot-long pier caps. The pier caps approached 100,000 pounds each, and were hauled to the site with a specialized transporter.

The project required a great deal of cooperation between County Materials, the contractor (Lunda Construction), and WisDOT. Lunda Construction did the formwork and fabricated the templates, and County Materials tied the rebar cages and executed the pour. The team used one of County Materials’ pouring beds to cast the pier elements. “(The pouring beds were) a big plus because you’re working with a perfectly flat surface,” says Roger Berg of Lunda Construction. “Extreme accuracy was critical with the precast units. We only had 5/16-inch tolerance (for matching the pier columns to the field poured footings), which is not much when you’re dealing with big #10 rebar. Everything had to be right on the money.”

Plans changed when the County Materials’ team discovered that the size and location of the couplers did not leave enough room for the radius of the stirrup rebar on the pier columns. The design had to be altered, requiring DOT approval before the project could move forward. “The DOT worked closely with us and we got the issue resolved very quickly,” says County Materials’ quality control and prestress manager Chris Kirchner. “I have a lot of respect for the way the DOT worked with us on this project.”

Construction of the Siggelkow Road bridge is proceeding smoothly as planned. Setting the piers, caps and girders took only a few days, and the project is expected to be completed on schedule by November1st despite a delayed start. The accelerated construction of the Sigglekow Road bridge is expected to save countless hours of commuter time by shortening the window of construction. Additional bridges along this stretch will also utilize ABC innovations.  “This is the future of bridge construction being implemented here,” says Kirchner.