Garver participated as a sub-consultant to HNTB on the design of the approach spans for the Great River Bridge, a new cable-stayed Mississippi River crossing near Arkansas City, Arkansas. The structure has a total length of approximately 22,000 feet and provides access across the Mississippi River for the future Interstate 69 route. The development of the new interstate facility should help stimulate growth in the delta region of both southeastern Arkansas and western Mississippi.
Based upon the importance of this structure to the traveling public, as well as the cost of the structure, the Great River Bridge is designated a "critical" bridge. This designation requires a very stringent evaluation of any anticipated seismic event. For this structure, the seismic loads are based on the "maximum probable earthquake," which corresponds to a return period of 2500 years. By comparison, a structure that is not designated as "critical" is typically designed for an earthquake within a return period of 475 years. In addition to the larger seismic event, the bridge is designed to withstand the seismic loads without sustaining significant damage. A site-specific response was developed for the project and the anticipated seismic loads were determined using a time-history analysis.
In addition to designing 17,000 linear feet of both steel plate girder and pre-cast concrete beam "approach spans" leading to the cable-stayed unit of the bridge, Garver also provided the approach bridge design. 500 feet of approach roadway design, right-of-way plans, and surveying services were provided by Garver. The surveys for the project include control surveys, base line surveys, controls for aerial mapping, utility surveys, field surveys, parcel surveys, right-of-way staking, and the hydrographic survey of the Mississippi River. Construction plans were recently completed and submitted for review.
Garver has also played a key role in the development of the Environmental Impact Statement for SIU #14, the segment of Interstate 69 between Shreveport, La. and El Dorado, Ark. Garver has participated in the public involvement process, developed design criteria, assessed the 20-mile Arkansas section of the corridor, and developed detailed alignments for the Line and Grade Study.
Line and grade work included horizontal alignment, vertical profiles, cross sections, drainage, interchanges and construction cost estimates. A minimum of four of the alignments will be evaluated through the NEPA process to select the final route location. Garver is teamed with URS and HNTB, among others for this project.
Garver is proud to participate in the development of the Interstate 69 Corridor, a national-scale project designed to improve our nation's roadways.