Lake Street Trunnion Bridge

(Bridge Hunter, Historic Bridges, Chicago Loop Bridges, John Marvig; 3D Satellite)

This bridge was built in 1916 because the Federal Government declared the center pier of swing bridges to be a navigation hazard and because Chicago bridge engineers were successful in perfecting the fixed trunnion bascule bridge. What was an adequate width for wood schooners became marginal for iron hulls and ridiculously narrow for steel hulls. The original design was going to use a lift span as was customary with railroad tracks. Though lift spans are considered OK for industrial areas such as the Calumet River or even more downstream on the South Branch,  a lift bridge was considered too ugly for the heart of downtown. Thus this was the first double-decker fixed trunnion bascule bridge ever designed and built. The Wells Street Bridge was a refinement of this design. Click the Historic Bridges link above for a diagram, pictures of the interior of the tender house, machinery room details and photos of how they built the new trunnion leaves around the swing bridge.

William Shapotkin posted
It is December 1960 and service on the Lake St 'L' continues to be provided by a fleet of 4000-series cars (due to the grade-level operation (under wire) west of Laramie Ave) -- as witnessed by the passing of this train over the South Branch of the Chicago River. View looks north. Earl Clark photo.
Myron Moyano A set of 4000's with the conductor's controls moved inside.

Dan Crespo -> Forgotten Chicago
Courtesy of CTA Flickr.
CTA posted
April 1924
A three-car Lake Street 'L' train crosses the South Branch of the Chicago River at Lake St., just west of the Loop.
The bridge was less than 10 years old at the time--built in 1916, this bi-level street and 'L' bridge replaced an older, bi-level swing bridge. Today, the bridge is used by Green Line (Lake Street) and Pink Line (Cermak Branch) trains. #CTA75 #FromTheArchives
Paul Webb shared
Glen Miller posted
Elevated train crossing Lake Street Bridge, Chicago, Illinois, 1924.
Paul Webb shared

In the reflections, it is interesting trying to figure out what are poles and what are smokestacks. Are the poles the masts of ships? Which of the smokestacks are on ships and which are on buildings?

Dan's comment: I blew it up a little and tried to clean it. You can see a little more detail here.

Marty Bernard posted
CTA 2000s, Lake Street L, the Lake Street Bridge over the South Branch of the Chicago River, 9/11/1975
Marty Bernard shared

Victor StLawrence comment
Lake Street Bridge (2014). Victor StLawrence Collection
[It is interesting that they raised both leaves for the sailboats. Sometimes they raise only one and expect the sailboats to use just half the river. Although when they raise just one, I think they raise the leaf a lot higher so that the boats have the entire half to use.]

 

A different view of the bridge in the raised position.

Historic Chicago posted

ChicagoLoopBridges posted
100 years ago today the swing bridge era came to an end at Lake St. In a period of 6 days L-traffic was crossing the new bascule. Read about it at:http://chicagoloopbridges.com/bridges12/SB12/LAKE12-5.html 
(Photo from 1915 Chicago Public Works Department Annual Report)

Chicago History Museum via DNAinfo,  March 6, 1916
[This must have been when they lowered the leaves of the new trunnion bridge for the first time. The leaves were built in the upright position while the swing bridge continued to operate so that streetcar traffic would not be interrupted. Then they stopped service, turned the swing bridge, cut out the middle, and lowered the leaves into the hole in the swing bridge to resume service.]

Steve Maresso posted two photos with the comment: "Here are 2 photos I took on October 1, 2014 showing the CTA Green Line El tracks which ride atop the Lake St Bridge in downtown Chicago. Interesting perspective."

[The cranes in the background are working on the foundation for 150 North Riverside.]

1, cropped

2

The CTA Holiday Train with Santa Claus and the South Branch "canyon" as background. (No Facebook login needed)

The W. E. Fitzgerald allided with this bridge in 1939 "tearing a hole in the bow and broke the forward mast in 1939." It allided with this bridge again "when the east span failed to open. Only a walkway on the bridge was damaged." (Note the dent at the top of the bow and the broken mast.) As a testament to the strength of this bridge, when the Fitzgerald allided with another bascule bridge, the span was knocked into the river and the Fitzgerald had minor damage. [BoatNerd] This is another reminder that the bridge tender is not in charge of this bridge, the CTA dispatcher is. He would be in a dark room someplace and can't see the urgency of a big ship bearing down on the bridge.

When I first wrote these notes, I saved the satellite image  because I knew it was going to change because they were going to build 150 North Riverside. The building is effectively built on pillars to fit it between the tracks.

3D Satellite

Here is the 2021 view.

3D Satellite

Here is a street view of the Lake Street Bridge that includes the new building so that you can see its V-shaped body that fit it between the tracks. You can also see that they are adding buildings to Wolf Point.

Street View, Aug 2019