Cortland Street Bridge under construction, looking east. (Courtesy Patrick McBriarty/PTM Werks)
The Cortland Street Bridge on Chicago’s north side crosses the Chicago River’s North Branch four miles above the mouth of the Chicago River at Lake Michigan. In 1982, the American Society of Civil Engineers recognized this bridge as an Engineering Landmark. It received Chicago Landmark status in 1991. To the frustration of area residents, this bridge has been closed to street traffic since June so the Chicago Department of Transportation can rehabilitate this more than 100-year-old bridge.
Old westbound bridge deck of the 5th Cortland Street Bridge, with new eastbound bridge deck in background. (Courtesy Patrick McBriarty/PTM Werks)
A simple bascule showing the advantage of a counterweight to balance the “seesaw” by moving the center of gravity at or very near the point of rotation. (Courtesy of Patrick McBriarty/PTM Werks)
The Cortland Street Bridge was the first ever Chicago-type bascule bridge. It opened to traffic on May 24, 1902.
Bascule is a French term meaning “seesaw” and may have originally meant to fall on one’s buttocks. The bridge employed this principle to open and close until the mid-1990s, when it was treated as a fixed structure and the operating equipment was decommissioned. I-beams were bolted across the center of the bridge to lock the two leaves together.
Cortland Street, formerly know as Clybourne Place after a local land owner and founder of the city’s early meat processing industry Archibald Clybourne, is expected to reopen on schedule November 1, 2015, weather permitting. According to CDOT, repairs to the truss superstructure at the approaches and reconstruction of the bridge’s south sidewalk are now complete. The work replacing the steel support beams and new open-grid, steel bridge deck is 45% complete. Reconstruction of the sidewalk for the southeast approach is now 50% complete, and repair of the truss superstructure over the river will also be completed.
Cortland Street Bridge project to replace stringers and open-grid bridge deck on August 24, 2015, looking east. (Courtesy of Patrick McBriarty/PTM Werks)
Thus far, the north sidewalk still carries pedestrian and bicycle traffic. We expect, before it is closed for reconstruction, the south sidewalk will be opened to maintain this pedestrian and bicycle connection across the river, throughout the project.
At the beginning of the 20th Century, City of Chicago engineers developed their own bridge design after a survey of European and North American moveable bridge literature. City Engineer John Ericson, frustrated by earlier private engineering designs, needed a robust solution to replace the many center-pier swing bridges of the day. New larger, wider steel ships plying the Great Lakes required removal of the center pivot islands which obstructed navigation. Ericson’s solution would become known nationally, and internationally, as the Chicago-type or Chicago style bascule bridge, which now dominates Chicago’s waterways and was based on the Tower Bridge in London.
Cortland Street Bridge in 1902 looking east from the Public Works Annual Report.
Today’s Cortland Street Bridge is the fifth at this location. The first Cortland Street Bridge was constructed sometime before 1849, and was succeeded by a second fixed, wood bridge, while and the third and forth bridges here were wood, hand-operated swing bridges removed in 1873 and 1901, respectively.
The Cortland Street Bridge looks much as it did when first constructed, with a few notable updates. In 1923 and 1951, the wood decks and floor stringers were renewed, similar to what is being done today. Also in 1951, the streetcar rails were refurbished, trusses were renewed, the counterweight boxes were completely rebuilt, the approach roadways were rebuilt with concrete slab, new handrails were installed, and the structure was repainted. In 1968, the bridge was again re-decked (at a cost of $515,000) with an open steel-grate decking. In 1997, the bridge superstructure and bridge deck were completely restored and repainted by the City of Chicago.
Cortland Street Bridge looking west. (Courtesy of Patrick McBriarty/PTM Werks)
An interesting element of this bridge is the raised markings reading “Carnegie” visible on many of the largest steel beams of the superstructure. The Carnegie Steel Company, founded in the 1870s, was sold in 1901 to the United States Steel Company or U.S. Steel as it is commonly known. The steel incorporated in this bridge may have been some of the very last Carnegie steel ever produced.
The fourth Cortland Street Bridge shown open over its protection pier in the center of the river channel.
