What is it called where the over pass arching supports meet the ground
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The structure where an overpass or bridge's arching supports meet the ground is called a bridge pier or bridge abutment. A bridge pier is a vertical structural element that supports the weight of the bridge and transfers it to the ground or the foundation. An abutment, on the other hand, refers to the outermost ends or supports of a bridge located at its boundaries, where the bridge deck connects to the ground on either side.
To identify the specific terminology for a particular bridge, it's best to refer to engineering drawings, structural documents, or architectural plans of the bridge in question.