Sometimes to move ahead you have to break the mold, literally. Wisdom holds that you can build a bridge faster or cheaper, not both. In the 1960s, Sundt pioneered a game changer – the soffit fill approach. This involved constructing bridges on fill dirt accumulated from the construction site, essentially building up an earthen mound as high as the bottom of the bridge, forming and placing a concrete waste slab on the mound, and then building the entire bridge on top. When finished, the dirt is removed.


We used the soffit fill technique to build the Bell Road Bridge over the State Route 303 Improvements in Glendale, Arizona, for the Arizona Department of Transportation. It allowed us to construct the bridge on the existing grade, then excavate the dirt out from under the bridge, resulting in significant cost and schedule savings.


Other notable benefits of the soffit fill method include not having to purchase and install shoring materials to support the bridge during construction, reduced use of cranes, forklifts and concrete pumps, and increased safety and productivity of the crews by working at ground level rather than on an elevated structure. Due to the many benefits of the soffit fill approach, it has been adopted by many state agencies as a preferred method for bridge construction.



State Route 303 Improvements


Arizona Department of Transportation