Analyzing deck conditions, superstructure ratings, and bad puns...
Analyzing deck conditions, superstructure ratings, and bad puns...
The average US bridge is 48 years old. That's a lot of birthday candles.
over I-405
7.8 N JCT SR 520
Parametric wireframe generated from real NBI dimensions. Drag to rotate, scroll to zoom.
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This bridge has a Fair overall condition rating of 6 out of 9. While it is not classified as structurally deficient, it shows some deterioration that is being monitored.
The bridge carries 30,405 vehicles per day and is 57 years old (reconstructed in 1996).
Its sufficiency rating of 63.4 places it below the national average of 63.6.
The NBI records a navigation clearance of 17 feet — the minimum vertical space below the bridge deck. The total height of the bridge structure (including towers, railings, and superstructure) may be higher.
For travelers with bridge anxiety
This bridge may cause some awareness for travelers with bridge anxiety, but has manageable characteristics.
This bridge is 292 feet long — a short crossing, about 10-15 seconds.
A standard overpass design with solid barriers on each side.
About 17 feet above ground — moderate height, similar to a 3-5 story building.
About 30,405 vehicles cross daily — moderate traffic, some congestion possible.
The deck is 78 feet wide with multiple lanes — easy to stay in a center lane.
This bridge crosses over land, not water — no water views below.
This comfort score is designed to help individuals with bridge anxiety plan their travel. All bridges in the National Bridge Inventory are regularly inspected and deemed safe for travel. This is not medical advice — if you experience severe anxiety, please consult a healthcare professional.
Year Built
1969
57 years old (rebuilt 1996)
Structure Type
Prestressed Concrete (Continuous) Box Beam (Multiple)
Total Length
292 ft
89.0 m
Deck Width
78 ft
23.9 m
Spans
2
sections between supports
Max Span
154 ft
longest unsupported section (46.9 m)
Traffic Lanes
5 lanes
Two-way traffic
Clearance Below
17 ft
navigation clearance under deck
Clearance height compared to familiar objects
Height shown is the navigation clearance below the bridge deck. The total height of the bridge structure (including towers and superstructure) may be higher.
Daily Traffic
30,405vehicles/day
47.74250°N, 122.18747°W
Prestressed Concrete (Continuous) Box Beam (Multiple)
A prestressed concrete box beam bridge combines hollow box sections with prestressing technology, enabling longer spans with reduced weight and material usage.
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Data from the National Bridge Inventory (NBI), maintained by the Federal Highway Administration (FHWA).
Data year: 2025. Conditions may have changed since the last inspection.
This information is provided for educational and informational purposes only. It should not be used as the sole basis for any decisions related to bridge safety or transportation planning. Always consult official sources and local authorities for the most current data.