MIDDLE RD
Carrying MIDDLE RD over ESTERO DE SAN ANTONIO
4.5 MI FROM S.R. 1, Marin, California
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: MIDDLE RD
The MIDDLE RD bridge in Marin, California carries MIDDLE RD over ESTERO DE SAN ANTONIO. It was built in 1958, making it 68 years old today. The structure is built primarily of concrete continuous and spans 6 sections, stretching 59.7 meters (196 feet) end to end. Daily traffic averages 40 vehicles, placing it in the lower-traffic tier of California bridges. It is owned and maintained by County Highway Agency.
The latest FHWA inspection records show a deck rating of 7/9, superstructure at 7/9, substructure at 4/9. The weakest component sits in poor condition. A component scored 4 or below, placing this bridge in the federal Poor condition category rather than declaring it unsafe or closed. Its NBI inventory load rating is 32.7 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How MIDDLE RD compares
Live comparison across California.
Historical Sufficiency Rating
PlainBridge-computedFHWA discontinued this calculated item; it does not determine current condition, funding eligibility, posting, or closure. How the historical reference is calculated.
Condition Ratings
Full 0–9 scale + sufficiency-rating breakdown: how condition ratings work.
Structural Details
- Year Built
- 1958
- Material
- Concrete Continuous
- Number of Spans
- 6
- Structure Length
- 59.7 m (196 ft)
- Deck Width
- 8.5 m (28 ft)
- Owner
- County Highway Agency
- Avg Daily Traffic
- 40 vehicles/day
- Structure Number
- 27C0124
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗Condition Analysis
- • The deck (driving surface) rates good at 7/9, with no significant deterioration on file.
- • The superstructure (beams and supports above the deck) is in good condition (7/9), showing no significant deterioration.
- • At 4/9, the substructure (piers and abutments) is in poor shape, with advanced wear flagged for priority repair.
How to read this record
MIDDLE RD is in the federal Poor condition category. That is a component-based result, not a closure order.
- NBI condition ratings reflect the latest record in this annual dataset, not a live status. Current routine inspection intervals are risk-based.
- Understand what Poor condition does and does not mean before drawing conclusions. Poor condition explained
- Compare MIDDLE RD against other structures in Marin and across California. California bridges
- Noticed visible damage or a safety concern? Report it to the agency that owns the bridge, or call 911 in an emergency. How to report a bridge
Condition codes come straight from the FHWA National Bridge Inventory and are not a real-time safety judgment. Only the owning agency, a state DOT, county, or other owner, can post, restrict, or close a bridge.
Frequently Asked Questions
What do the condition ratings mean for MIDDLE RD?
MIDDLE RD in Marin, California has a deck rating of 7/9, superstructure rating of 7/9, and substructure rating of 4/9 on the FHWA's 0–9 scale.
How often is MIDDLE RD inspected?
MIDDLE RD's responsible agency sets its routine interval under FHWA's risk-based inspection rules; this page does not expose the scheduled interval. It carries about 40 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. MIDDLE RD is currently shown as Poor condition from its component ratings; that category is not a live closure or safety decision.
What is the inventory load rating for MIDDLE RD?
MIDDLE RD has an NBI inventory load rating of 32.7 metric tons.
Who is responsible for maintaining MIDDLE RD?
MIDDLE RD is owned and maintained by County Highway Agency.
How old is MIDDLE RD and does age affect safety?
MIDDLE RD was built in 1958, making it 68 years old.
Disclaimer: Bridge condition data is from the FHWA NBI and reflects the last reported inspection. A Poor condition rating is not a live declaration that a bridge is closed or unsafe for travel. For current closure, posting, or safety information, contact the responsible transportation agency.
Every figure on PlainBridge is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.