Capitalizing on our segmental bridge expertise to lead us into a new market, RS&H was selected in 2009 to serve as Owner’s Representative for the Virginia Department of Transportation’s (VDOT) Route 460 Connector Phase I Design-Build project. A major part of the project was the construction of the Grassy Creek Bridges, now the tallest in the Commonwealth of Virginia, for which our team oversaw construction engineering and inspection (CEI) services. When the entire Route 460 Connector project is complete, it will provide an essential link between Kentucky and Virginia through the Appalachian Mountains.
As RS&H’s first CEI project outside the state of Florida, the remote mountainous location and snowy winter weather posed a new learning curve for the team. Despite the challenges, the team was able to develop unique solutions that supported the project.
Cast-In-Place in the Mountains
The bridges and new roadway were being constructed as part of an extensive, ongoing economic development effort through the mountainous terrain of southwest Virginia. Construction of the Grassy Creek Bridges, one of the most complex structures in the country, took place in an extremely remote location. Because of the steep, narrow roads leading up the mountain, as well as the geotechnical restrictions associated with potential foundation locations, a unique, cast-in-place, balanced cantilever method of segmental construction was chosen since the pieces would be too large to cast off-site and transport.
Grout Test Gets National Attention
We worked closely with the contractor to develop a full-scale grout test of a tendon on the project site before actual grouting on the Grassy Creek Bridges. The test featured an approximately 140 foot grouted tendon within a duct, which allowed the team to test grout from multiple major producers. Once the grout had set, the tendon was cut apart to identify which grout performed the best, and the superior grout was brought to VDOT.
The use of the proper grout test will result in the avoidance of water build-up in the caps, which can lead to corrosion and structure weakening. As a result of the test, specification and material changes have taken place not just in Virginia, but nationally. In addition to grouting tests, our team worked directly with VDOT in using the post-tensioning specifications for this project to update the department’s statewide post-tensioning specifications, ensuring they met current standards.
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