About the Bridge
The Michigan Avenue Bridge is the first double-deck, double-leaf trunnion bascule bridge ever built.
First conceived by architect Daniel Burnham in his 1909 “Plan for Chicago,” the Michigan Avenue Bridge was to be a gateway between Chicago’s north and south sides. Edward Bennett designed the bridge following the Beaux-Arts style and in keeping with Burnham’s concept. Bridge construction began in 1917 and it was opened for traffic in 1920 with a grand celebration that included cannon fire and marching bands. The Michigan Avenue Bridge has indeed become a much-used connection between Chicago’s north and south, just like Burnham had envisioned. Today, thousands of people traverse the bridge daily.
… the Michigan Avenue Bridge was to be a gateway between Chicago’s north and south sides.
The Michigan Avenue Bridge is a Double Bascule Trunnion. A bascule bridge is a drawbridge hinged with a counterweight that continuously balances the leaf throughout the entire upward swing in providing clearance for boat traffic. The leaves in this instace refers to Michigan Avenue. Because it has two leaves, the Michigan Avenue Bridge is a Double Bascule Trunnion. Trunnion refers to the pin and supporting bearing that forms the hinge, allowing the leaves to move up and down. So precise is the balance of the leaves and trunnions of this double-deck bridge, it only takes two 108-horsepower motors to open and close each of the 3,750-ton bridge leaves. An engineering wonder even today, the bridge’s massive and precise gears are viewable from inside the Bridgehouse Museum.
The bridge and bridgehouses were designated as a Chicago Landmark in 1991 by the City of Chicago and the State of Illinois.
