Designated a landmark by the American Society of Civil Engineers, the Cortland Street Bridge is a double-leaf bascule span that became in the early twentieth century the standard for movable bridges designed by the city engineer of Chicago. The Cortland Street bridge was the first of this type and featured electric motors that drove pinion gears which engaged a rack attached to the end of each truss. Counterweights on the shore sides of the bridge counterbalanced the roadway and superstructure that spanned the river and thus little power was required to raise or lower the bridge. When raised, each leaf assumed a nearly vertical position providing a wide clearance for vessels plying the river. City engineers designed the machinery so that the bridge could open within one minute during calm weather and under three minutes during windy conditions.
From a report prepared for the American Historic Engineering Record, 1987. HAER photos by Jet Lowe.
Length of largest span: 127.9 ft.
Total length: 216.8 ft.
Deck width: 36.0 ft.
Vertical clearance above deck: 16.1 ft.
Eligible for the National Register of Historic Places
Approximate latitude, longitude
+41.91694, -87.66361(decimal degrees) 41°55'01" N, 87°39'49" W (degrees°minutes'seconds")
Approximate UTM coordinates
USGS topographic map
IL 016-6011 (Illinois bridge number)
BH 15116 (Bridgehunter.com ID)
Inspection (as of 09/2011)
Deck condition rating: Good(7 out of 9) Superstructure condition rating: Poor(4 out of 9) Substructure condition rating: Fair(5 out of 9) Appraisal: Structurally deficient
Sufficiency rating: 37.9 (out of 100)
Average daily traffic (as of 2010)
October 8, 2013: New Street View added by J.P.
May 17, 2010: Updated by J.R. Manning: Added description from HAER Report
July 25, 2008: New photos from James Baughn
HAER IL-138 - Chicago River Bascule Bridge, West Cortland Street, Spanning North Branch of Chicago River at West Cortland Street, Chicago, Cook County, IL
James Baughn - webmaster [at] bridgehunter [dot] com