While preparing this post I learned that this bridge, and three others in Joliet are Scherzer Rolling Lift Bascule Bridges. Now that's a mouthful! The name refers to the design of the bridge. I'm including this link to a site with more information about these historic bridges if you are interested. The photos and the descriptions there are much better than mine.
The Cass Street Bridge is in the raised position in this photo. The enormous gray concrete blocks are the counterweights that enable it to roll on a track to raise and lower the two sections of the bridge deck.
Looking to our right we saw the first barge approaching after passing under the Jackson Street Bridge, which remained in the raised position to allow a second barge to pass.
Looking to our left as the first barge passed in front of us, the Jefferson Street Bridge was raising. You can see the green deck of the first barge passing from our right to our left.
Looking to the right again we saw the Jackson Street Bridge lowering after the second barge had passed under it.
This photo shows the counterweight rising as the bridge deck begins to lower.
Here the counterweight is nearly in its fully raised position and the bridge deck is almost in place.
At last the safety gates lift and we are on our way. The raising and lowering of bascule bridges only takes a very few minutes which is why it was such a popular design in the 1900s. We have crossed these magnificent bridges many times but never had a front row seat to watch and photograph the three as they raised and lowered.
Lovin' Life ~~ And Lucky Timing