Practical trigonometry… the science of the stability of triangles in everyday travel and transportation, is seen in Chicago’s historic bridges. Isn’t knowledge and the benefit of hard work worth preserving? Of course it is… and we live with proof of that each day.
Superstructures, Decking, Approach Spans, and Sidewalks of Chicago Bridges
Note the common denominator of triangular structures in these elements of infrastructure. It’s true… stong stems come from healthy roots!
Lateral bracing in the substructure of the LaSalle Street Bridge is vital to the stability of this massive leaf. Lattice bracing and the steel roadway deck form is visible.
Lateral bracing stabilizes the train deck approach span of the Lake Street Bridge. Triangular elements are present in the Warren Truss of the clear span on the right.
The Wells Street Bridge sports elaborate lateral bracing, floor beams, sidewalk supports, and the Warren Truss in its substructure. Each leaf of this bridge weighs about 2,500 tons. The bridge serves CTA trains, vehicles, and pedestrians.
Lateral substructure bracing of the modern Columbus Drive bridge on the Main Branch, Chicago River. This is the second bridge to lift after the Outer Drive Bridge.
Lateral bracing and lattice bracing of the Dearborn Street Bridge’s substructure and within the abutment’s hefty walls.
Telephoto of the State Street Bridge’s lateral bracing and lattice bracing and V-lacing of the substructure, with the floor support system.
The substructure, sidewalk deck supports, and marine navigation lights on the State Street Bridge during a boat run.
The Ida B. Wells (Congress Parkway) Bridge’s lateral bracing and deck truss elements.
Signal gantry structures also have triangular bracing. These signal systems are over tracks used by METRA; two trains are in the background.
Divi Logan. Chicago. January 29, 2020.