Allegheny County, Pennsylvania, has more structurally deficient bridges than any other county in the United States—201 of 1,250, or 16 percent. Improvements would cost at least $150 million.
Structurally deficient bridges are characterized by deteriorating conditions and reduced load-carrying capacity. Although this classification does not imply that a bridge is unsafe, it does indicate that the bridge likely requires significant repair and maintenance to remain in service and eventually may need major rehabilitation or replacement.
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Source: The Place Database. www.lincolninst.edu/research-data/data/place-database