There is a big abutment for that bridge just north of Kinzie kind of hidden in a yard or loading dock area. If I remember correctly its stone and brick and may contain an arch or other design feature.
There might be another abutment a little further north in another yard, before you get to Hubbard.
When they took down the rest of the Logan Square L from Lake St. up to the new subway the bridge over the Milwaukee Road and CNW lines was left in place both because of the issues of removing it over active railroad tracks AND because both railroads were using it as a stand for their signals. It still serves the purpose of holding the signals
There is an excellent article in the Feature section on the main page called Remnants of the L By Terance Banich. He goes into great detail about the old elevated lines and has a lot of photos including a few of the bridge.