Total bridges
125
Public highway bridges in Tuolumne County
County profile · official public datasets
Tuolumne County, CA
125 public highway bridges tracked in the FHWA National Bridge Inventory: 36% rated Good, 56.8% Fair, 7.2% Poor.
- 125
- Public bridges
- 36%
- Good condition
- 7.2%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Tuolumne County pairs a higher-than-median Poor-condition share among rated counties in the state with an older average build year than the state inventory.
- 33rd
- of 58 on Poor share
- 7.2%
- Poor-condition share
- 125
- public highway bridges
- 1964
- avg year built
Poor is an FHWA condition category from the lowest applicable component rating (4 or below), not a live crossing-safety or closure decision. Rankings cover counties with at least five public highway bridges.
Tuolumne County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Tuolumne County ranks #33 of 58 California counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 7.2%). Tuolumne County, California contains 125 public highway bridges. Roughly 36% are rated “Good,” 56.8% “Fair,” and 7.2% “Poor.” Poor means the lowest applicable deck, superstructure, substructure, or culvert rating is 4 or below on the 0–9 NBI scale. It is a condition category, not a live safety or closure decision.
Responsible agencies inspect covered bridges on risk-based intervals under current NBIS rules and submit inventory data to FHWA annually. The list below shows every NBI-tracked bridge in the county. Use the “Sort by” controls to change the ordering, and click any row for its reported inspection date, traffic count, and condition fields.
Source: FHWA National Bridge Inventory. See methodology for full definitions.
Good condition
36%
45 of 125 rated 7-9
Fair condition
56.8%
71 of 125 rated 5-6
Poor condition
7.2%
9 of 125 rated 4 or below
In-state Poor-share rank
#33 of 58
Among California counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 125 NBI-tracked bridges by lowest applicable component rating.
Good 36% (45)
Fair 56.8% (71)
Poor 7.2% (9)
Tuolumne County's Poor-condition bridges carry 48,030 vehicle crossings a day
That is 12.2% of the county's reported daily bridge traffic on 7.2% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 5,337 crossings a day against 3,933 for a Good-condition one. A Poor rating is a condition category, not a closure or a live safety judgement; it means the lowest applicable component rating is 4 or below.
Computed over the 125 of 125 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
64.8% of Tuolumne County's bridges have passed the 50-year mark
81 of the 125 bridges with a recorded construction year were built in 1974 or earlier. Age alone is not a defect: a well-maintained older bridge can rate Good, and 36% of this county's inventory does. Even so, this older cohort is the population from which future Poor ratings are drawn, which is why the age profile below matters alongside the condition split above.
Cutoff derives from the 2024 release year minus a 50-year design life. Source: FHWA National Bridge Inventory, 2024 release.
One structure carries 52.2% of the county's Poor-condition bridge traffic
MONO WAY over SULLIVAN CREEK, built 1991, carries 25,060 vehicles a day, the most of any Poor-rated structure here. The county's Poor-condition exposure is concentrated rather than evenly spread, so the 9-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 48,030 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Tuolumne County's bridges were built
125 bridges with a recorded construction year, grouped by decade
- 1900s 2
1900–1909
2 bridges
- 1910s 7
1910–1919
7 bridges
- 1920s
1920–1929
11 bridges
- 1930s
1930–1939
10 bridges
- 1940s 8
1940–1949
8 bridges
- 1950s
1950–1959
10 bridges
- 1960s
1960–1969
19 bridges
- 1970s
1970–1979
23 bridges
- 1980s 8
1980–1989
8 bridges
- 1990s
1990–1999
10 bridges
- 2000s 7
2000–2009
7 bridges
- 2010s 8
2010–2019
8 bridges
- 2020s 2
2020–2029
2 bridges
What this shows Construction peaked in the 1970s, when 23 of the county's bridges still in the inventory were built, which is 18.4% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year is 1964, 6 years older than the California average of 1970.
How Tuolumne County compares with California's closest counties by inventory size
The 5 California counties nearest Tuolumne County in number of bridges, with their condition splits. Its 7.2% Poor share is the 2nd-lowest of these 6. Its average build year of 1964 against a peer-group mean of 1967 is in line with the group.
Showing the 5 closest of 57 California counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Nevada County | 135 | 45.2% | 40.7% | 14.1% | 1972 |
| Lake County | 129 | 30.2% | 62% | 7.8% | 1970 |
| Yuba County | 127 | 37.8% | 55.9% | 6.3% | 1967 |
| Tuolumne County (this page) | 125 | 36% | 56.8% | 7.2% | 1964 |
| Sutter County | 121 | 33.9% | 52.9% | 13.2% | 1968 |
| Mariposa County | 109 | 21.1% | 67.9% | 11% | 1956 |
Each share is of that county's own total tracked bridges; peers are the counties with 5 or more bridges whose inventory size is closest to Tuolumne County's. Source: FHWA National Bridge Inventory, 2024 release.
Nationwide counties with similar inventory size or average build year
Two NBI-derived peer sets for Tuolumne County, both outside California so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside CA (125 bridges here).
- Hoonah-Angoon County, AK · 125 bridges
- Worth County, GA · 125 bridges
- Stone County, MS · 125 bridges
- Carroll County, OH · 125 bridges
Similar average build year
Nearest mean year-built outside CA (1964 here).
- Bergen County, NJ · avg 1964 · 577 bridges
- Morris County, NJ · avg 1964 · 508 bridges
- Baltimore city County, MD · avg 1964 · 374 bridges
- Ross County, OH · avg 1964 · 356 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Poor-condition bridges (9)
WINDING ROAD
PoorOver: UPPER HUNTER CREEK
NO DATA ENTERED, Tuolumne, CA
Built 1969 ADT: 50
WINDING ROAD
PoorOver: STANISLAUS RIVER
NO DATA ENTERED, Tuolumne, CA
Built 1926 ADT: 50
WINDING ROAD
PoorOver: BLUE CANYON CREEK
NO DATA ENTERED, Tuolumne, CA
Built 1968 ADT: 50
WINDING ROAD
PoorOver: MILL CREEK
NO DATA ENTERED, Tuolumne, CA
Built 1969 ADT: 50
ITALIAN BAR RD
PoorOver: ROSE CREEK
10.7 MI NE BIG HILL ROAD, Tuolumne, CA
Built 1925 Load: 15.6 t ADT: 20
STATE ROUTE 120
PoorOver: CHINESE CREEK
10-TUO-120-14.73, Tuolumne, CA
Built 1914 Load: 16.2 t ADT: 2,800
SR 108
PoorOver: MONO WAY
10-TUO-108-R2.20, Tuolumne, CA
Built 2004 Load: 32.4 t ADT: 17,450
PARROTTS FERRY RD
PoorOver: NEW MELONES RESERVOIR
4 MILES SOUTH OF ROUTE 4, Tuolumne, CA
Built 1978 Load: 32.4 t ADT: 2,500
MONO WAY
PoorOver: SULLIVAN CREEK
0.5 MI E OF HWY 108, Tuolumne, CA
Built 1991 Load: 32.4 t ADT: 25,060
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges
Every figure on PlainBridges 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. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.