Pennsylvania is home to more than 6,000 structurally deficient bridges, according to the Federal Highway Administration. That's about out of every five of the state's 30,000 bridges.

So where are these bridges?

A new map from Keystone Crossroads answers that question.

The project is part of the publication's series "Rust or Revival?" which explores "the urgent challenges pressing upon Pennsylvania's cities."

The media outlets undertaking the project are WHYY, WITF, WESA and WPSU.

When it comes to structurally deficient bridges, explains WHYY's Marielle Segarra:

"Bridges are rated on a scale of 0-9, with 0 being the worst. Each section of the bridge — superstructure, substructure, and deck — is rated separately. If any one gets a rating of 4 or below, the bridge is structurally deficient. The map colors reflect each bridge's lowest rating."

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As Pennsylvania's Department of Transportation points out, however, being listed as deficient does not necessarily mean the structure is in danger of collapse.

"Being rated structurally deficient does not mean that a bridge is unsafe; rather it means that it has deterioration to one or more of its major components," PennDOT writes.

"Although deterioration is present, a structurally deficient bridge is safe. Safety is our number one priority and if a bridge is found to be unsafe, it's closed. If a bridge can only carry certain loads, it's restricted."

Map of Structurally Deficient Bridges in Pennsylvania

Zoom in to see bridges in your city or county. Click on a dot to see information about each bridge, including the type and year it was built.