You should have seen the video of the move by now.  The effort to float the new span into place was pretty impressive.  The joints are a tight tolerance to be met but you are moving a large barge with a tug to get them there and those are not the most subtle of tools.  however, a combination of the big pushes from the tug and putting lines on to the other moored barges allowed the team to carefully control the position of the barge and get the span in to place.

This was a popular thing.  It happened mid morning on a sunny day so plenty of people came out to see it.  TV crews were running around near me filming it and I was trying to get along the river to get different angles while still having the time lapse running in one spot (and hopefully nobody stealing the camera on the tripod while I am not looking).  The TV camera operator I was chatting to was a lot of fun.  They had been told to come out but not told too much.  However, they were glad to be watching something fun rather than filming the less happy sides of city news.

With the barge in place, the crews got to work attaching the span.  The first task was the bolt the lower spar in to place.  The crews were climbing over these area getting the bolts in place.  There seemed to be a large contingent of people standing watching this happen.  Far more seemed to be watching rather actually doing anything at this point but I imagine a fair number of city people wanted to see such a high profile job get done.

The last step would be to put the remaining structure in place to complete the truss.  That had to be done so the span could then support itself.

Once the old part of the bridge is cut away, the next step is getting the remaining part of the bridge ready to accept the new structure.  The original construction of the bridge involves having the metalwork riveted together.  In the run up to the replacement program, it appears that the team have progressively removed the individual rivets in the sections that will be part of the new joint and replace them with bolts.  Then, when the structure is cut, it is possible to unbolt the stubs left after the cuts.

With the sections removed, some preparation was necessary for the surfaces that would be part of the new joints with the mating surfaces and the bolt holes being coated.  A bunch of cleaning up was also required so the team were moving around these joints on cherry pickers with power tools to clean and prep the surfaces.

The final step was to bolt in place some additional structure that would serve to guide the new span into place when it was floated in to position.  All of this took a lot longer than I expected.  One visit at night looked like a lot of things we ready.  I talked to some of the crew to find out when the move would take place.  They thought it would all be done overnight.  I debated whether I was prepared to stay up all night to watch it and decided that wasn’t a good idea.

I was glad I made that decision.  I awoke early the next morning and headed around and the new span was not yet moved.  I was glad to know I hadn’t missed it.  Indeed, the prep work was still being finished off.  In the end, one of the guys came by and advised of the timing of the lunch break for that shift so I knew that I had time before the move and could head home and get some breakfast!

Meanwhile, there were a few guys cutting up sections of the old span.  Not sure what their plan was but the cutting work always looks great at night.

Here we find ourselves repeating some previous posts.  Hopefully, this will be slightly different.  A while back I posted about the replacement of the south span of the Wells Street Bridge.  You can look back at the previous posts here and here.  During the previous replacement, I got half of the story.  I saw the original span being cut free and moved out of place.  Sadly, I had to be out of town for the rest of the week and did not see the new span being put in place and attached.

This time it all happened a bit in reverse for me.  I was sure I was going to be around to see the new span put in place.  What I hadn’t counted on was that they were a lot quicker removing the original span.  By the time I made my first visit, the original section had been cut free and floated off to be moored along the river.  I was a bit annoyed at myself but I guess I shouldn’t have been surprised that the second time around they would have found out ways of doing it all a bit more quickly.

One of the things I did find fun was looking at the cuts that had been made to remove the old section.  The jagged metal edges look very cool, particularly when you contemplate how long that structure has been sitting across the Chicago River.