Main Street Underpass at Grand Trunk Western Railroad Grade Separation Study and Gateway Design
DLZ provided survey, right-of-way engineering, environmental services, railroad, highway and utility design engineering services for the north-south corridor grade separation study and ultimately final design, of arterial routes within the City of Mishawaka.
DLZ gathered existing railroad and highway traffic and accident data, utility and topographic data, and right-of-way and environmental data from governmental agencies and other sources. The data was analyzed to select four alternate crossings for further study. The impacts and benefits of a grade separation at each of the four crossings were analyzed and a preferred crossing was selected for a detailed study of its development as a grade separation. Ultimately, the highway under/railroad over alternate, with the existing railroad grade maintained, was selected and a detailed preliminary design was completed.
The final design for the railroad bridge is a two-span, simple-span steel deck girder bridge with a concrete deck. Also included in the design is a temporary railroad runaround supported by anchored steel sheet piling. There are also several types of retaining walls on this project. At each of the four quadrants of the bridge is a 50 foot long cast-in-place concrete, cantilever retaining wall with aesthetic facing panels. Adjacent to these walls are modular block retaining walls. These walls are 516 feet long north of the bridge on both sides of the road and 48 feet long south of the bridge on both sides of the road.
Adjacent to the roadway there are also short, cast-in-place concrete, cantilever retaining walls. These walls are approximately 1,094 feet long and are used to raise the sidewalk above the roadway. In addition to the bridge, there is approximately 2,200 feet of roadway construction, the modernization of traffic signals at the intersection of Broadway and Main Street, and Jefferson Boulevard and Main Street, as well as the construction of storm sewer. The corridor was fully landscaped.