Rosenberg Associates was consultant on the Dixie Drive Interchange project to Horrocks Engineers, the Utah Department of Transportation (UDOT), and the City of St. George.
Civil design services included a hydraulic analysis to determine the impacts of the Dixie Drive interchange and roadway improvements to the adjacent Southgate Golf Course and Santa Clara River flood plain. Based on the results of the hydraulic analysis, the Southgate Golf Course was redesigned to mitigate effects of the Dixie Drive interchange and roadway construction. The redesign of the golf course included 4 new holes designed as part of the project row mitigation. Utility design was also required to accommodate changes to area water, sewer and storm drain to allow the proposed roadway improvements. Prior to construction, a FEMA Conditional Letter of Map Revision was completed to address changes to the Santa Clara River flood plain. Post construction, a FEMA Letter of Map Revision was completed to verify construction followed the hydraulic design criteria and revise the regulatory maps.
Geotechnical services for the new interchange included subsurface exploration and sampling, cone penetration testing (CPT), seismic refraction studies, laboratory testing, and engineering analyses. Specific analyses included liquefaction, long term settlement, slope stability, rock fall, bedrock rippability, shallow and deep foundation (driven and drilled shafts), and pavement (asphaltic concrete and Portland cement concrete). Based on the results of the field investigation, laboratory testing and engineering analyses, geotechnical recommendations were provided for the design and construction of the new interchange project. Geotechnical services were also provided for the new trailhead facilities associated with the Dixie Drive Interchange.