2012 Issue

68 Project Description The Mountain View Corridor 2100 North Project will provide an east-west corridor connecting Interstate 15 and Redwood Road in northern Utah County. The current Lehi 2100 North roadway extends west from I-15 about one mile and a gravel road extends east from Redwood Road about one mile; however, there is not direct con- nection between these two roads across the Jordan River. Phase I of the project in- cludes the design and construction of two one-way frontage roads located roughly 300 feet apart, preserving space for con- struction of a future freeway between the frontage roads as demand increases and funding becomes available. The new roadways were designed to be constructed predominantly in shallow cuts and on low fills with at-grade intersections. One major exception is the section of the frontage roads across the Jordan River Basin. Each frontage road across the basin will be constructed on embankments up to about 30 feet in height over lengths of about 900 feet. Right-of-way needs and impacts to the Jordan River Basin were re- duced by retaining the outer edges of the roadway embankments usingmechanically stabilized earth (MSE) walls. Each of the two frontage roads will pass over two bridge sites within the Jordan River Basin. One pair of bridges will be located at the east side of the river basin and will carry traffic across the river. A second pair of bridges will be located at the west side of the basin to accommodate future access road and trail development. The frontage roads will also pass beneath railroad bridges designed and constructed as part of the UTA FrontRunner South com- muter rail project. The railroad grades will remain near the existing ground surface, with the frontage roads constructed in cuts up to about 28 feet deep. The Utah Department of Transportation contracted with Parsons Brinckerhoff for design of the project. RB&G Engineering was retained as a subconsultant for geo- technical engineering. UDOT selected Lehi- based Hadco Construction to construct the project. Roadway Embankments Thirty shallow test borings were performed to evaluate subsurface conditions for the portions of roadway located on shallow cuts and fills. Clayey soils were encountered within about two feet of the existing ground surface throughout the project area, and generally controlled the pavement design for the project. Thirteen exploratory borings and four cone penetrometer tests were performed to eval- uate the subsurface conditions within the Jordan River Basin. The subsurface profile consists of Lake Bonneville deposits. The test holes encountered predominantly soft and firm clay extending to a depth of about 100 feet. Dense granular soils with artesian water pressures underlie the clayey soils. Geotechnical Aspects of Mountain View Corridor 2100 North Project By Brad Price, Brandon Horrocks, Jacob Price, and Rob Johnson