Total bridges
32
Public highway bridges in Alpine County
County profile · official public datasets
Alpine County, CA
32 public highway bridges tracked in the FHWA National Bridge Inventory: 34.4% rated Good, 59.4% Fair, 6.3% Poor.
- 32
- Public bridges
- 34.4%
- Good condition
- 6.3%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Alpine County pairs a better-than-median Poor-condition share among rated counties in the state with an older average build year than the state inventory.
- Top 43%
- lowest Poor share in state
- 6.3%
- Poor-condition share
- 32
- 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.
Alpine County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Alpine County ranks #25 of 58 California counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.3%). Alpine County, California contains 32 public highway bridges. Roughly 34.4% are rated “Good,” 59.4% “Fair,” and 6.3% “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
34.4%
11 of 32 rated 7-9
Fair condition
59.4%
19 of 32 rated 5-6
Poor condition
6.3%
2 of 32 rated 4 or below
In-state Poor-share rank
#25 of 58
Among California counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 32 NBI-tracked bridges by lowest applicable component rating.
Good 34.4% (11)
Fair 59.4% (19)
Poor 6.3% (2)
Alpine County's Poor-condition bridges carry 815 vehicle crossings a day
That is 2.2% of the county's reported daily bridge traffic on 6.3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 408 crossings a day against 1,111 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 32 of 32 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
65.6% of Alpine County's bridges have passed the 50-year mark
21 of the 32 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 34.4% 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 66.3% of the county's Poor-condition bridge traffic
STATE ROUTE 4 over SILVER CREEK, built 1952, carries 540 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 2-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 815 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Alpine County's bridges were built
32 bridges with a recorded construction year, grouped by decade
- 1920s 1
1920–1929
1 bridges
- 1930s
1930–1939
6 bridges
- 1940s 2
1940–1949
2 bridges
- 1950s
1950–1959
5 bridges
- 1960s
1960–1969
6 bridges
- 1970s 1
1970–1979
1 bridges
- 1980s
1980–1989
9 bridges
- 2010s 2
2010–2019
2 bridges
What this shows Construction peaked in the 1980s, when 9 of the county's bridges still in the inventory were built, which is 28.1% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year is 1964, 6 years older than the California average of 1970.
How Alpine County compares with California's closest counties by inventory size
The 5 California counties nearest Alpine County in number of bridges, with their condition splits. Its 6.3% Poor share is the 2nd-lowest of these 6. Its average build year of 1964 against a peer-group mean of 1970 is 6 years older.
Showing the 5 closest of 57 California counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| San Benito County | 76 | 46.1% | 43.4% | 10.5% | 1971 |
| Inyo County | 66 | 63.6% | 31.8% | 4.5% | 1972 |
| Sierra County | 65 | 40% | 52.3% | 7.7% | 1972 |
| Amador County | 61 | 37.7% | 37.7% | 24.6% | 1966 |
| Mono County | 49 | 63.3% | 24.5% | 12.2% | 1970 |
| Alpine County (this page) | 32 | 34.4% | 59.4% | 6.3% | 1964 |
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 Alpine 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 Alpine County, both outside California so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside CA (32 bridges here).
- Lincoln County, GA · 32 bridges
- Butte County, ID · 32 bridges
- Alpena County, MI · 32 bridges
- Wheeler County, OR · 32 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.
All bridges (32)
BLUE LAKES RD
FairOver: WEST FORK CARSON RIVER
3.0 MI SOUTH OF S.H. 88, Alpine, CA
Built 1960 Load: 15.9 t ADT: 400
STATE ROUTE 89
FairOver: WEST FORK CARSON RIVER
10-ALP-089-21.31, Alpine, CA
Built 1940 Load: 17.5 t ADT: 2,150
STATE ROUTE 89
FairOver: EAST FORK CARSON RIVER
10-ALP-089-13.30, Alpine, CA
Built 1934 Load: 18.1 t ADT: 950
STATE ROUTE 88
FairOver: WEST FORK CARSON RIVER
10-ALP-088-14.70, Alpine, CA
Built 1952 Load: 18.5 t ADT: 3,225
STATE ROUTE 89
FairOver: MARKLEEVILLE CREEK
10-ALP-089-14.69, Alpine, CA
Built 1929 Load: 18.8 t ADT: 840
PLSNT VLY RD
FairOver: HOT SPRINGS CREEK
1.1 MI W/O MARKLEEVILLE, Alpine, CA
Built 1974 Load: 20.7 t ADT: 400
STATE ROUTE 88
FairOver: WEST FORK CARSON RIVER
10-ALP-088-12.46, Alpine, CA
Built 1939 Load: 22.0 t ADT: 2,200
OLD STATE ROUTE 88
FairOver: WEST FORK CARSON RIVER
10-ALP-088-16.22, Alpine, CA
Built 1939 Load: 23.3 t ADT: 3,200
STATE PARK ROAD
FairOver: HOT SPRINGS CREEK
GROVER HOT SPRINGS ST PK, Alpine, CA
Built 1964 Load: 29.2 t ADT: 400
STATE ROUTE 4
FairOver: EAST FORK CARSON RIVER
10-ALP-004-29.78, Alpine, CA
Built 1940 Load: 30.1 t ADT: 490
STATE ROUTE 88
FairOver: CAPLES LAKE SPILLWAY
10-ALP-088-0.46, Alpine, CA
Built 1987 Load: 32.4 t ADT: 2,800
STATE ROUTE 4
FairOver: PACIFIC CREEK
10-ALP-004-11.99, Alpine, CA
Built 1937 Load: 32.4 t ADT: 1,250
DIAMOND VALLEY RD
FairOver: WEST FORK CARSON RIVER
SOUTH OF SH 88, Alpine, CA
Built 1987 Load: 32.4 t ADT: 1,000
DIAMOND VALLEY RD
FairOver: INDIAN CREEK
0.8 MI E AIRPORT RD, Alpine, CA
Built 1956 Load: 32.4 t ADT: 157
HIGHLAND LAKE RD
FairOver: MOKELUMNE RIVER
3.3 MI S OF S.H. 4, Alpine, CA
Built 1989 Load: 32.4 t ADT: 25
STATE ROUTE 4
FairOver: RAYMOND MEADOW CREEK
10-ALP-004-24.47, Alpine, CA
Built 1963 Load: 33.0 t ADT: 490
WOLF CREEK RD
FairOver: SILVER CREEK
0.2 MI E/O SR 4, Alpine, CA
Built 1956 Load: 37.6 t ADT: 280
LARAMIE ST
FairOver: MARKLEEVILLE CREEK
E/O MONTGOMERY ST, Alpine, CA
Built 1958 Load: 38.2 t ADT: 200
STATE ROUTE 89
FairOver: WEST FORK CARSON RIVER
10-ALP-089-21.46, Alpine, CA
Built 1960 Load: 64.2 t ADT: 3,200
HORSE MEADOWS ROAD
GoodOver: WILLOW CREEK
NO DATA ENTERED, Alpine, CA
Built 1983 Load: 23.0 t ADT: 8
HORSE MEADOWS ROAD
GoodOver: WILLOW CREEK
NO DATA ENTERED, Alpine, CA
Built 1984 Load: 24.3 t ADT: 8
STATE ROUTE 4
GoodOver: NORTH FORK MOKELUMNE RIV
10-ALP-004-12.94, Alpine, CA
Built 1937 Load: 32.4 t ADT: 490
STATE ROUTE 4
GoodOver: SILVER CREEK
10-ALP-004-27.98, Alpine, CA
Built 1986 Load: 32.4 t ADT: 580
DOUGLAS WAY ROAD
GoodOver: WEST FORK CARSON RIVER
0.1 MILE NORTH OF SH 88, Alpine, CA
Built 1987 Load: 32.4 t ADT: 100
DIXON MINE RD
GoodOver: WOLF CREEK
4 MI SOUTHEAST OF SR4, Alpine, CA
Built 2019 Load: 32.4 t ADT: 280
STATE ROUTE 89
GoodOver: WILDLIFE ACCESS
10-ALP-089-R19.15, Alpine, CA
Built 1980 Load: 33.0 t ADT: 3,050
STATE ROUTE 4
GoodOver: JACKASS GULCH
10-ALP-004-R7.82, Alpine, CA
Built 1982 Load: 38.2 t ADT: 1,250
STATE ROUTE 88
GoodOver: WEST FORK CARSON RIVER
10-ALP-088-17.76, Alpine, CA
Built 1963 Load: 44.4 t ADT: 3,200
STATE ROUTE 88
GoodOver: WEST FORK CARSON RIVER
10-ALP-088-16.13, Alpine, CA
Built 1963 Load: 44.7 t ADT: 3,200
10N01
GoodOver: WOODS CREEK
NO DATA ENTERED, Alpine, CA
Built 2012 Load: 53.8 t ADT: 50
CRYSTAL SPRGS CAMP
PoorOver: WEST FORK CARSON RIVER
0.1 MILE SOUTH OF S.H. 88, Alpine, CA
Built 1938 Load: 24.0 t ADT: 275
STATE ROUTE 4
PoorOver: SILVER CREEK
10-ALP-004-26.15, Alpine, CA
Built 1952 Load: 36.9 t ADT: 540
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.