Carter County, Kentucky
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Kentucky Transportation Cabinet (KYTC) Fuller, Mossbarger, Scott & Mat Engineers
Horne & Trammel Construction Co.
Over 68,000 bridges or abutments across the U.S. are classified as scour critical by FHWA standards. In 1999, the Kentucky Transportation Cabinet (KYTC) through the efforts of Fuller, Mossbarger, Scott & Mat Engineers and funding from the FHWA proposed a series of bridge scour contracts to protect 17 scour critical bridges in six counties.
The project required A-Jacks concrete armor units to be placed within an engineered matrix along the abutment of a bridge at Stinson Creek and downstream on both sides of the creek. A total of 900 24-in. A-Jacks units were placed after excavation of the affected area including the location of a failed, poured concrete abutment. A-Jacks were placed along the toe of the slope reaching from the bridge abutment to an area downstream. Protecting the toe meant stability of the slope that also served to support Route 60, a main county highway. Rock ripraps was used to backfill and stabilize the forces of erosion on each embankment.
From the time of entry into the stream, the installation required only two days. Four laborers and a track hoe were used to prepare the area for placement of the hard armor as well as backfill the units at the end of construction. A-Jacks are recognized as a permanent high performance and cost effective toe stabilization technology used with hard armor backfill or bioengineered systems and have been written in to HEC-23 as one of six acceptable scour countermeasures endorsed by the FHWA.
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