The project consisted of a complete reconfiguration of the interchange, including lowering the existing mainline I-74 to the grade of existing I-155 and removal of the bridges that carry it through the interchange and raising the interchange ramps from I-155 over I-74. I-155 will then be elevated over I-74 at an improved trumpet style interchange.
TERRA was entrusted to complete the development of the Maintenance of Traffic component along with a complete topographic and hydraulic survey of the project. A value engineering (VE) study was undertaken to analyze the original MOT plan presented as part of the Phase I project. This analysis determined that the original provision of providing one lane of traffic in each direction might cause significant backups and delay. Therefore, the concept layout of the revised MOT was designed to provide two lanes of traffic in each direction. This revised concept requires nine separate phases of construction with several detours to allow traffic to be maintained while the mainline is lowered. TERRA Engineering is responsible for creating the design plans for the MOT. During the development of the concept, proper coordination with the structural engineer for the design of the necessary temporary structural elements (temporary retaining walls) was required.