U.S. HIGHWAY 101
Carrying U.S. HIGHWAY 101 over MILLER CREEK
04-MRN-101-15.35, Marin, California
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
U.S. HIGHWAY 101 in Marin, California sits above 22% of rated California bridges on inventory load rating (25 t), while its 1952 build year is earlier than 64% of Marin's recorded-year cohort (207 bridges).
U.S. HIGHWAY 101 in Marin, California is rated Fair in the FHWA's 2024 National Bridge Inventory. Built in 1952, it carries 3 rated components on the inspecting agency's 0-9 scale, and its weakest reported component scores 5. The lowest applicable rating sets the federal condition category, so this Fair result describes the weakest reported component rather than the structure as a whole. No NBI category is a closure decision or a live crossing-safety verdict.
NBI record plate
Structure CA:27 0004
INTERSTATE-ERA · CONCRETE · MULTI-SPAN · TIED-CTRL · HEAVY-ADT · STANDARD-LOAD · CAT-FAIR
- INTERSTATE-ERA 1950–1979
- CONCRETE Concrete
- MULTI-SPAN 3 spans
- TIED-CTRL Tied control
- HEAVY-ADT Heavy ADT
- STANDARD-LOAD Standard load
- CAT-FAIR Fair
Inspection-sheet codes from this record’s year, material family, spans, controlling component, ADT, inventory load, and NBI category, not a live closure verdict.
Bridge Snapshot: U.S. HIGHWAY 101
The U.S. HIGHWAY 101 bridge in Marin, California carries U.S. HIGHWAY 101 over MILLER CREEK. It was built in 1952, making it 74 years old today. It was last reconstructed in 1987, extending its service life. The structure is built primarily of concrete continuous and spans 3 sections, stretching 26.8 meters (88 feet) end to end. Daily traffic averages 151,000 vehicles, placing it in the heavily-trafficked tier of California bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show a deck rating of 5/9, superstructure at 5/9, substructure at 7/9. The weakest component sits in fair condition. None of this bridge's reported major components fall into the Poor condition range.
How U.S. HIGHWAY 101 compares
Age against the county: built in 1952, earlier than 132 of Marin's 207 bridges with a recorded construction year (64%), against a county median build year of 1959. Age is not a defect on its own, but it is the population from which future Poor ratings are drawn.
Live comparison across California bridges with a recorded inventory load rating (25,538 of 25,848 rated).
U.S. HIGHWAY 101 vs every rated California bridge
Inventory load rating (metric tons), FHWA NBI, this state
25 Top 78% higher than 22% of 25,538 bridges
rated California bridges, bucketed by value
Each bar is a band; taller bars hold more bridges. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source FHWA National Bridge Inventory · August 2026
Condition Ratings
Full 0–9 scale + sufficiency-rating breakdown: how condition ratings work.
Reported 0–9 component ratings from the FHWA NBI. The highlighted component is the lowest reported input to this record’s current condition category; it is not a closure or live crossing-safety decision.
Marin inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 207 bridges in this county. Orthogonal to this structure's component profile above: a county catalog share, not a live crossing-safety verdict.
Structural Details
- Year Built
- 1952
- Last Reconstructed
- 1987
- Material
- Concrete Continuous
- Number of Spans
- 3
- Structure Length
- 26.8 m (88 ft)
- Deck Width
- 43.2 m (142 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 151,000 vehicles/day
- Structure Number
- 27 0004
Condition Analysis
- • The deck (driving surface) rates fair at 5/9, minor deterioration that routine maintenance should address.
- • The superstructure (beams and supports above the deck) is in fair condition (5/9), with minor deterioration that may require routine maintenance.
- • The substructure (piers and abutments) is in good condition (7/9), showing no significant deterioration.
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗How to read this record
This page shows what the last federal inspection recorded, not whether U.S. HIGHWAY 101 is safe to cross today. Here is how to use it.
- NBI condition ratings reflect the latest record in this annual dataset, not a live status. Current routine inspection intervals are risk-based.
- Learn how the 0–9 condition scale and Good/Fair/Poor categories are defined. How condition ratings work
- Compare U.S. HIGHWAY 101 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 U.S. HIGHWAY 101?
U.S. HIGHWAY 101 in Marin, California has a deck rating of 5/9, superstructure rating of 5/9, and substructure rating of 7/9 on the FHWA's 0–9 scale.
How often is U.S. HIGHWAY 101 inspected?
U.S. HIGHWAY 101'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 151,000 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. U.S. HIGHWAY 101 is currently shown as Fair condition from its component ratings; that category is not a live closure or safety decision.
What is the inventory load rating for U.S. HIGHWAY 101?
U.S. HIGHWAY 101 has an NBI inventory load rating of 24.6 metric tons.
Who is responsible for maintaining U.S. HIGHWAY 101?
U.S. HIGHWAY 101 is owned and maintained by State Highway Agency.
How old is U.S. HIGHWAY 101 and does age affect safety?
U.S. HIGHWAY 101 was built in 1952, making it 74 years old and last reconstructed in 1987.
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.
Share this inspection record
Send this source-bounded record or download its data card. An NBI condition category is not a closure or live crossing-safety verdict.
Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. Component ratings, ADT, and condition category on this page are copied from the NBI record for this structure; no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2024 NBI release. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.