substructure

There is a risk that the barges could come into contact with the “substructure” of the bridge, the McKees Rocks Police Department said in a statement early Saturday confirming the closure.

The state must replace both the bridge’s superstructure and part or all of the substructure, he said.

The overall rating of a bridge is based on whether the condition of any one of its individual components — the deck, superstructure, substructure or culvert, if present — is rated poor or below.

They will repair and replace steel truss and substructure elements, as well as sway frames and timber sidewalks.

Last fall, a crew of six installed the sculpture’s substructure, made up of thin, stainless steel cables and rings supporting the individually installed cast pieces that were attached one by one.