Assembling the Main Span “Pier Tables”

During the past two weeks, in the wee morning hours, large flatbed trucks have hauled giant 50 foot-long steel girders onto the construction site near the Bridge Replacement Project’s east tower. The girders for the west tower will arrive soon. The huge steel beams are so large that the flatbed bed truck requires a second driver at the rear of the trailer to help guide the load through the construction site, much like an aerial ladder fire truck.

The girders are manufactured in Arizona and travel hundreds of miles on trucks that arrive late at night to minimize any effect on traffic. In fact, their travel along the interstate system is carefully planned to avoid significant traffic impacts.

There are two kinds of girders for the new bridge’s main span: floor and edge girders. The floor beams are the larger ones, measuring eight feet high. As the name implies, they will extend width-wide across the pier table, providing the main horizontal support for the span. The edge girders will run the length of the span and along the edges of the bridge segment, and have steel sleeves on the exterior edge where the stay cables will run. Into this framework of steel beams, 20-foot-by-30-foot concrete panels will be placed to form the road deck. In the photo above, a section of floor beam is being hoisted into position prior to bolting to a northern edge girder to form the “pier tables” – which will be the first sections of the main span to be put in place.

Once both pier tables are assembled, they will be hoisted up and placed onto the falsework around each tower. The first pier table raising, for the east tower, is scheduled to occur in April, and then main span construction will begin.