The construction team is completing necessary preparations to jack the arch ribs apart, which lifts them off their falsework and forces each rib to support its own weight.
As part of the preparation, crews meticulously calibrate the equipment using a process that we described earlier this year. Additionally, crews removed the formwork from the spandrel columns, which extend from the arches to the deck, and installed cradles cast into the arch ribs to hold the hydraulic cylinder that powers the jack.
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| On the left, you can see a couple of spandrel columns that crews exposed by removing the formwork. One column still has the formwork in place. |
Finally, using a crane, workers will hoist the large hydraulic ram jacks and place them into the cradles.
Once the jacking starts next week, crews will survey and mark the columns at each stage to evaluate how the movement is affecting the columns and abutments. On day one, crews will jack the arch to an 80 percent threshold and then engineers will determine if there was any pressure shift in an up-close inspection. The next day, crews will jack the arch ribs to 100 percent threshold, and will check them again.
Once the arch ribs are separated and lifted, crews can pour the concrete closure that completes each arch and allows them to stand on their own.
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