Arch completion photo story, part 1 of 3

From ODOT- Over the past few months, we’ve told you how the long-span arch ribs that will support the southbound Interstate 5 bridge over the Willamette River in Eugene and Springfield took shape section by section. Through a series of highly complex and technical steps, tons of concrete and steel were transformed into a pair of arches that are both useful and elegant.



Here’s another close-up look at each step in the process, showing the various stages of the arch completion. This week, we'll start by taking you 50 feet underground for the first stage of the arch ribs construction.



In April 2010, crews had installed temporary falsework to form the arches as they were built. They started by erecting steel supports on the work bridge and welding them into place. On top of the steel supports, they built a wooden deck and forms that outlined the curve of the arches.



Rebar (reinforcing steel bars) creates the strength and shape of the concrete arches. Below, two crew members put the finishing touches on one of the rebar cages that form the arch.

After the cages were sealed off with plywood form work, workers began filling them with a mixed concrete “cocktail” that is capable of flowing like water so that it fills every nook and cranny within the arch reinforcement cages. See the photo below.