STATE ROUTE 55
STATE ROUTE 55 in 12-Ora-055-R5.99-Cms, Orange County, California received a condition grade of C (58/100). Built in 1966, the bridge carries 167K vehicles daily on STATE ROUTE 55 over Interstate 405.
STATE ROUTE 55 carries a C on the BridgeSafety Condition Score with 58/100. Component ratings sit in the middle of the FHWA NBI distribution; rehabilitation programming is likely on the owning agency’s medium-term horizon.
The bridge was built in 1966 and is now 60 years old, at or past the typical 50-year design life for bridges of its vintage. Maintenance and inspection cycles are correspondingly more involved than for newer structures. STATE ROUTE 55 carries an average daily traffic count of 167,000 vehicles, with 9 lane(s) crossing Interstate 405. The owning agency is State Highway Agency; bridge inspection records flow into the federal NBI database annually.
Component Ratings
The riding surface, evaluated for cracking, spalling, and wear
Beams, girders, and trusses that support the deck
Piers, abutments, and foundations below the deck
Bridge Details
About This Bridge
STATE ROUTE 55 is a 60-year-old bridge located 12-Ora-055-R5.99-Cms in Orange County, California. The bridge carries STATE ROUTE 55 over Interstate 405 with 9 traffic lanes, handling approximately 167K vehicles per day. Built in 1966, the structure spans 87.8 meters.
The bridge received a Condition Grade of C (58/100) based on Federal Highway Administration inspection data. Its deck is rated 5/9 (fair), superstructure 5/9 (fair), and substructure 7/9 (good).
This bridge is owned and maintained by State Highway Agency.
Location Map
Frequently Asked Questions
STATE ROUTE 55 has a Condition Score of 58/100 (Grade C). Its deck is rated 5/9, superstructure 5/9, and substructure 7/9 on the NBI scale. The bridge is not classified as structurally deficient.
STATE ROUTE 55 was built in 1966, making it 60 years old. The average bridge age in the United States is 48 years.
STATE ROUTE 55 carries approximately 167K vehicles per day (average daily traffic). The bridge has 9 traffic lanes. It is 87.8 meters long and located on STATE ROUTE 55 in 12-Ora-055-R5.99-Cms, Orange County, California.
No, STATE ROUTE 55 is not classified as structurally deficient. All three primary components (deck, superstructure, and substructure) are rated above 4 on the 0-9 NBI scale.
STATE ROUTE 55 is located 12-Ora-055-R5.99-Cms in Orange County, California. The bridge carries STATE ROUTE 55 over Interstate 405. Its coordinates are 33.687019, -117.872253. It is maintained by State Highway Agency.
STATE ROUTE 55 carries STATE ROUTE 55 over Interstate 405. The bridge is 87.8 meters long and was built in 1966.
Condition Score is calculated from deck (33%), superstructure (33%), and substructure (34%) NBI ratings with an age penalty for bridges over 50 years.
Source: FHWA National Bridge Inventory, 2026.