Holes in the bridge

From ODOT-

Did you know that there are holes on the underside of the Whilamut
Passage Bridge?

Specifically, there are access holes that allow ODOT workers to get inside
of the hollow bridge beams for inspections and maintenance.  

Every two years, ODOT inspects its bridges and on large spans
special access holes allow workers to inspect the interior of bridge beams and
decks and make any necessary repairs. Each span of the new Whilamut Passage Bridge
has its own access holes, which measure 24 inches by 36 inches. If you look up
when standing under the bridge, you can tell how many beams support each span
by counting the access holes.  

The inspectors receive special training to ensure they won’t get
claustrophobic while working in such an enclosed, dark space. Security doors are
installed inside the access holes and locked in between inspections and
repairs.  

Workers get ready to enter one of the access holes to finish the interior surfaces of the bridge's concrete beams and decks.

Here you can see part of the rebar skeleton that makes up the bridge beams. the arrows point to plugs that create the oval access holes when concrete is poured for the beams.