I-5
I-5 in 4.5 N JCT SR 900, King County, Washington received a condition grade of B (65/100). Built in 1966, the bridge carries 122K vehicles daily on I-5 over Terrain.
I-5 carries a B on the BridgeSafety Condition Score with 65/100. Most component ratings are solid; one or two may show wear consistent with the structure’s age, but the bridge is not flagged as structurally deficient.
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. I-5 carries an average daily traffic count of 122,487 vehicles, with 5 lane(s) crossing Terrain. 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
I-5 is a 60-year-old bridge located 4.5 N JCT SR 900 in King County, Washington. The bridge carries I-5 over Terrain with 5 traffic lanes, handling approximately 122K vehicles per day. Built in 1966 and reconstructed in 1992, the structure spans 184.1 meters.
The bridge received a Condition Grade of B (65/100) based on Federal Highway Administration inspection data. Its deck is rated 6/9 (fair), superstructure 6/9 (fair), and substructure 7/9 (good).
This bridge is owned and maintained by State Highway Agency.
Location Map
Frequently Asked Questions
I-5 has a Condition Score of 65/100 (Grade B). Its deck is rated 6/9, superstructure 6/9, and substructure 7/9 on the NBI scale. The bridge is not classified as structurally deficient.
I-5 was built in 1966 and reconstructed in 1992, making it 60 years old. The average bridge age in the United States is 48 years.
I-5 carries approximately 122K vehicles per day (average daily traffic). The bridge has 5 traffic lanes. It is 184.1 meters long and located on I-5 in 4.5 N JCT SR 900, King County, Washington.
No, I-5 is not classified as structurally deficient. All three primary components (deck, superstructure, and substructure) are rated above 4 on the 0-9 NBI scale.
I-5 is located 4.5 N JCT SR 900 in King County, Washington. The bridge carries I-5 over Terrain. Its coordinates are 47.561361, -122.322056. It is maintained by State Highway Agency.
I-5 carries I-5 over Terrain. The bridge is 184.1 meters long and was built in 1966, with reconstruction in 1992.
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.