Precast Arch Installation Sequence

Clients are often curious about precast arch installations and how quickly they can be completed. The following photos help illustrate the way the materials are shipped to a jobsite, as well as how the crane handles the units.

The units are delivered to the jobsite on their side.

The crane lifts the unit from the truck, rotating it in the air before setting it.

The foundations feature a 3″ deep keyway, and the arch legs are set onto a 1″ pad of shims. Adjustments can be made in the shims to accommodate for any variations in the foundation. This keyway will be grouted to create a level bearing surface for the entire arch structure.

Units feature chamfered butt joints with a recommended ¼” to ½” joint spacing.

Wingwalls are full-height panels delivered face down to the site ready to set onto foundations. Inserts in the walls and end arch units allow for connections with large steel plates. The deadman anchors cast into the wall will resist overturning once backfilled. The contractor also places grout between a small lower portion of the anchor and the foundation to resist sliding.

The contractor installs a drainage pipe behind the wall prior to placing and compacting free-draining structure backfill.

Video footage credit: Mike Hanna, PEC West

The last few items before backfill include applying a joint-wrap, securing filter fabric at wingwall joints and placing grout in the arch keyways and between the wingwall anchors and foundations. There’s no delay to wait for concrete cure times, so backfill can begin just days after installation. A well-planned installation can result in a bridge open to traffic in less than a month.