Did you know? The oldest bridge in the NBI was built in 1697.
Did you know? The oldest bridge in the NBI was built in 1697.
Connecting the data points... literally.
over MOUNTCASTLE DR (3975)
IN JOHNSON CITY
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 55,938 vehicles per day and is 51 years old.
Its sufficiency rating of 67.9 is above the national average of 63.6.
The NBI records a navigation clearance of 15 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 186 feet long — a short crossing, about 10-15 seconds.
A standard overpass design with solid barriers on each side.
About 15 feet above ground — standard overpass height.
About 55,938 vehicles cross daily — heavy traffic, congestion likely during rush hours.
The deck is 44 feet wide with 2-3 lanes — moderate width.
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
1975
51 years old
Structure Type
Concrete (Continuous) Box Beam (Multiple)
Total Length
186 ft
56.6 m
Deck Width
44 ft
13.4 m
Spans
3
sections between supports
Max Span
94 ft
longest unsupported section (28.6 m)
Traffic Lanes
2 lanes
One-way traffic
Clearance Below
15 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
55,938vehicles/day
36.34292°N, 82.36940°W
Concrete (Continuous) Box Beam (Multiple)
A concrete box beam bridge uses hollow rectangular concrete sections. The box shape provides excellent torsional resistance and allows for longer spans.
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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.