Box girder beam bridge construction

From ODOT- Arches, pier columns, precast beams, cast-in-place beams, decking and railing are all bridge components. When joined together, they link Interstate 5 across the Willamette River.



Joining the south bank of the Willamette to the freeway, the bridge is made up of support pier columns, box girder beams, a deck and railings. On some bridges, the beams are made off-site; however, the beams on these bridges are what we call cast-in-place beams.



Let me share the process of building the cast-in-place beams. Piles were first driven to support a steel platform for the wooden falsework. The falsework forms the outline of the beams just like a house foundation. Inside the wooden forms, reinforcing steel is tied together forming the floor, walls and roof of the beam. The floor is poured and cured, and then the sides and the top are constructed. The finished rectangular beams look solid but are actually hollow and are from 5 to 12 feet high and vary in length from 84 to 214 feet.



Then the deck is formed and poured on top of the beams, completing the bridge. Finally, all the supports and falsework are removed leaving the bridge standing on the pier columns.