the city of chicago has about 45 movable bridges, according to chicagoriver.org. many of these you can drive over in your car or walk over, some you can go over in the el, but as far as i know there is only one that has foot traffic, el traffic, and pedestrian traffic all at the same time. i took the opportunity of a beautiful day to go stand on the wells street bridge and record the sounds that the bridge makes. i walked to the center of the bridge, where the two halves of the bridge separate to let tall boats through, and i listened to traffic going over the grates of the bridge, hitting the interlocking metal things that hold the halves together, and exiting on the other side on the way to the loop. the first recording (listen 1) is the sound of cars going over the bridge. the second recording (listen 2) is the sound of the el going over the bridge above the cars as the usual chicago city noises like horns and sirens can be heard in the background.

the pictures are of the wells street bridge as the el passes above the cars. they were taken from the lasalle street bridge.