Serving approximately 38,000 vehicles, 50 freight trains and 41 passenger trains every day, the 130th Street and Torrence Avenue grade separation project on Chicago’s south side is a true structural engineering marvel. Now open to the public, the project has transformed one of the city’s most congested intersections into a sophisticated, multi-tiered grade separation featuring depressed, realigned and widened roadways with six new bridges.
Numerous Value Planning/Value Engineering studies were performed throughout the life of the project in order to determine not only what would be built as part of the grade separation, but how. One of the greatest examples of VE in action on this project is present in the design and construction of the top tier commuter railroad truss for the CSS & SB/NICTD: a 394-foot-long, double track, ballasted deck, through truss structure which was built off-site and rolled into place using Self-Propelled Modular Transporters (SPMTs). Using this Accelerated Bridge Construction (ABC) technique resulted in a short, eight-hour shutdown of Norfolk Southern Railway operations. Derived from 25 ideas which were speculated, grouped into alternatives and evaluated for performance and acceptance, this innovative piece of the construction puzzle was the first major infrastructure completed for the project.
The final design and construction schedule for the top tier truss bridge resulted in more than $600,000 in savings for the structure, eliminating six months of construction through ABC techniques. Its completion early on in the grade separation’s construction allowed commuter rail traffic to continue through the area as construction activities continued on other project elements below. The new truss bridge was the longest steel truss span ever rolled into place at the time of installation.