Bridges are inspected every two years at minimum; bridges in poor condition are inspected more frequently. These inspections rate the conditions of various bridge elements. The inspection records are stored in a bridge management system. The Federal Highway Administration annually collects data on bridges more than 20 feet long from each state’s department of transportation, including the Pennsylvania Department of Transportation and New Jersey Department of Transportation, and stores it in their National Bridge Inventory.

This analysis considers a bridge's deck, super, and substructure ratings, or the culvert rating for a culvert. A score between 0 and 9 is given for each component. Bridges with scores between 7 to 9 for all three components are rated "good," those with any component scores of 4 or lower are rated "poor." A bridge that doesn't fall into a good or poor rating is considered “fair”.

Most bridges are on state roads and are maintained by the state’s department of transportation. Some bridges are on local roads and are maintained by local governments. The "Other" category covers bridges maintained by turnpike and toll authorities.