EarthTec, a specialist in mechanically stabilized earth (MSE) structures and subsidiary to GeoStructures, has completed the design work and begun delivering wall components needed for improvements to the I-495 highway at Telegraph Road. Part of the $2.52-billion effort to build the new Woodrow Wilson Bridge span across the Potomac River, this project features a grade-separated interchange and widening of I-495 for about two miles, which will keep traffic moving more smoothly through the often-congested area.
Under an agreement with general contractor CK Constructors, EarthTec’s MSE wall system will be used for retaining walls and bridge abutments, including several pile-supported integral bridge abutments. When the project is completed in late 2009, it will have 29 EarthTec structures totaling 130,000 square feet for 11 ramps and bridges. Other structures on the project include five box culvert extensions, drainage improvements, CIP retaining walls, and noise walls.
The unique challenges at Telegraph Road led CK to adopt EarthTec’s 5-foot-by-10-foot precast concrete panel MSE system because its ribbed steel strips can be positioned to avoid obstructions such as drainage structures and bridge-support piles. EarthTec uses the widest and thickest galvanized, ribbed-steel strip in the industry, so it can reinforce the earth with fewer strips and allow for larger spans between strips to accommodate obstructions. In addition, since the strips are wider at the point where they are bolted to the precast panels, tensile capacity is maximized, and corrosion is minimized at the most critical location of the bolt hole, all of which contribute to better wall performance.
These benefits are partly what led the Virginia Department of Transportation to approve EarthTec’s MSE system last year as “Category A,” thus pre-approving its use in all typical bridge abutments and retaining wall applications.