Total bridges
609
Public highway bridges in Sonoma County
County profile · official public datasets
Sonoma County, CA
609 public highway bridges tracked in the FHWA National Bridge Inventory: 24.1% rated Good, 69% Fair, 6.9% Poor.
- 609
- Public bridges
- 24.1%
- Good condition
- 6.9%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Sonoma County posts a higher-than-median Poor-condition share among rated counties in the state across large county bridge inventory.
- 31st
- of 58 on Poor share
- 6.9%
- Poor-condition share
- 609
- public highway bridges
- 1967
- 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.
Sonoma County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Sonoma County ranks #31 of 58 California counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.9%). Sonoma County, California contains 609 public highway bridges. Roughly 24.1% are rated “Good,” 69% “Fair,” and 6.9% “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
24.1%
147 of 609 rated 7-9
Fair condition
69%
420 of 609 rated 5-6
Poor condition
6.9%
42 of 609 rated 4 or below
In-state Poor-share rank
#31 of 58
Among California counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 609 NBI-tracked bridges by lowest applicable component rating.
Good 24.1% (147)
Fair 69% (420)
Poor 6.9% (42)
Sonoma County's Poor-condition bridges carry 340,018 vehicle crossings a day
That is 5.3% of the county's reported daily bridge traffic on 6.9% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 8,096 crossings a day against 11,374 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 609 of 609 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
67.2% of Sonoma County's bridges have passed the 50-year mark
409 of the 609 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 24.1% 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 13.4% of the county's Poor-condition bridge traffic
US HIGHWAY 101 over DRY CREEK ROAD, built 1960, carries 45,500 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 42-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 340,018 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Sonoma County's bridges were built
609 bridges with a recorded construction year, grouped by decade
- 1900s 6
1900–1909
6 bridges
- 1910s 14
1910–1919
14 bridges
- 1920s 46
1920–1929
46 bridges
- 1930s 29
1930–1939
29 bridges
- 1940s 12
1940–1949
12 bridges
- 1950s
1950–1959
69 bridges
- 1960s
1960–1969
160 bridges
- 1970s
1970–1979
113 bridges
- 1980s 42
1980–1989
42 bridges
- 1990s 49
1990–1999
49 bridges
- 2000s 31
2000–2009
31 bridges
- 2010s 30
2010–2019
30 bridges
- 2020s 8
2020–2029
8 bridges
What this shows Construction peaked in the 1960s, when 160 of the county's bridges still in the inventory were built, which is 26.3% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1967) matches the California average (1970).
How Sonoma County compares with California's closest counties by inventory size
The 5 California counties nearest Sonoma County in number of bridges, with their condition splits. Its 6.9% Poor share is the 3rd-lowest of these 6. Its average build year of 1967 against a peer-group mean of 1970 is in line with the group.
Showing the 5 closest of 57 California counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Kern County | 668 | 50.1% | 43.3% | 6.6% | 1972 |
| Alameda County | 658 | 35.3% | 55.2% | 9.6% | 1973 |
| San Joaquin County | 644 | 33.7% | 57.1% | 9.2% | 1968 |
| Contra Costa County | 618 | 42.6% | 46.9% | 10.5% | 1977 |
| Sonoma County (this page) | 609 | 24.1% | 69% | 6.9% | 1967 |
| Tulare County | 589 | 42.4% | 54.2% | 3.4% | 1959 |
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 Sonoma 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 Sonoma County, both outside California so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside CA (609 bridges here).
- Palm Beach County, FL · 610 bridges
- Mobile County, AL · 612 bridges
- Allen County, IN · 613 bridges
- Weld County, CO · 614 bridges
Similar average build year
Nearest mean year-built outside CA (1967 here).
- Allegheny County, PA · avg 1967 · 1,294 bridges
- Suffolk County, MA · avg 1967 · 489 bridges
- Multnomah County, OR · avg 1967 · 473 bridges
- Le Flore County, OK · avg 1967 · 469 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
All bridges (609)
CLEVELAND AVE
FairOver: PAULINE CREEK
0.3 MI N GUERNEVILLE RD, Sonoma, CA
Built 1963 Load: 24.3 t ADT: 13,000
CALISTOGA ROAD
FairOver: AUSTIN CREEK
N INTRX WITH S.R. 12, Sonoma, CA
Built 1960 Load: 24.3 t ADT: 17,770
PINER ROAD
FairOver: PINER CREEK
IN SANTA ROSA, Sonoma, CA
Built 1960 Load: 24.3 t ADT: 5,900
COFFEY LANE
FairOver: PINER CREEK
0.1 MILES S/O PINER ROAD, Sonoma, CA
Built 1960 Load: 24.3 t ADT: 3,100
MARLOW ROAD
FairOver: PINER CREEK
MARLOW ROAD, Sonoma, CA
Built 1960 Load: 24.3 t ADT: 2,300
MARLOW RD
FairOver: PAULINE CREEK
MARLOW RD, Sonoma, CA
Built 1960 Load: 24.3 t ADT: 12,500
SNYDER LN
FairOver: BRANCH OF FIVE CREEK
1.1 MI N ROHNERT PARK EXP, Sonoma, CA
Built 1965 Load: 24.3 t ADT: 1,500
SNYDER LANE
FairOver: COPELAND CREEK
0.5 MI N E. COTATI AVE, Sonoma, CA
Built 1960 Load: 24.3 t ADT: 3,124
COMMERCE BLVD
FairOver: HINEBAUGH CREEK
0.1 MI N RNPK EXPRESSWAY, Sonoma, CA
Built 1970 Load: 24.3 t ADT: 500
E COTATI AVE
FairOver: FLOOD CONTROL DITCH
0.1 MI NE OLD REDWOOD HWY, Sonoma, CA
Built 1960 Load: 24.3 t ADT: 3,000
GEYSERS RD
FairOver: GIRD CREEK
0.4 MI N OF SR 128, Sonoma, CA
Built 1960 Load: 24.3 t ADT: 500
WATMAUGH ROAD
FairOver: RODGERS CREEK
0.3 MI W ARNOLD, Sonoma, CA
Built 1960 Load: 24.3 t ADT: 4,000
RAILROAD AVE
FairOver: DOWDALL CREEK
0.3 MI S/O VERANO, Sonoma, CA
Built 1961 Load: 24.3 t ADT: 524
ST HELENA ROAD
FairOver: VAN BUREN CREEK
1.2 MI W CALISTOGA RD, Sonoma, CA
Built 1952 Load: 24.3 t ADT: 2,100
GILMORE AVENUE
FairOver: GOSSAGE CREEK
0.1 MI N/O DERBY LANE, Sonoma, CA
Built 1972 Load: 24.3 t ADT: 100
SCENIC AVE
FairOver: NO NAME CREEK
0.1 MI W OF S MOORLAND AV, Sonoma, CA
Built 1950 Load: 24.3 t ADT: 615
MECHAM RD
FairOver: STEMPLE CREEK
S OF 9TH ST, Sonoma, CA
Built 1970 Load: 24.3 t ADT: 3,300
PEPPER RD
FairOver: STEMPLE CREEK
4 MI W OF US 101, Sonoma, CA
Built 1970 Load: 24.3 t ADT: 3,500
WALKER RD
FairOver: GOSSAGE CREEK
AT VALLEY FORD ROAD, Sonoma, CA
Built 1967 Load: 24.3 t ADT: 250
RAINSVILLE RD
FairOver: MARIN CREEK
0.5 MI W STONY POINT RD, Sonoma, CA
Built 1950 Load: 24.3 t ADT: 3,200
CASA GRANDE AVE
FairOver: ADOBE CREEK
0.4 MI N ELY RD, Sonoma, CA
Built 1970 Load: 24.3 t ADT: 1,600
CASA GRANDE AVE
FairOver: ADOBE CREEK
0.25 MI S ADOBE RD, Sonoma, CA
Built 1970 Load: 24.3 t ADT: 2,000
E RAILROAD AVE
FairOver: LICHAU CREEK
0.1 MI E PETALUMA HILL RD, Sonoma, CA
Built 1970 Load: 24.3 t ADT: 750
SWEETWATER SPRG RD
FairOver: BRANCH REDWOOD CREEK
1.2 MI NE ARMSTRNG WOOD R, Sonoma, CA
Built 1970 Load: 24.3 t ADT: 140
SWEETWTR SPRNGS RD
FairOver: PORTER CREEK
7.7 MI W ARMSTRONG RD, Sonoma, CA
Built 1968 Load: 24.3 t ADT: 140
ADOBE CANYON ROAD
FairOver: HILLSIDE
1.1 MI NW/O SR 12, Sonoma, CA
Built 1965 Load: 24.3 t ADT: 650
DUTCHER CREEK RD
FairOver: DUTCHER CREEK
0.1 MI N DRY CREEK RD, Sonoma, CA
Built 1957 Load: 24.3 t ADT: 900
SKAGGS SPRINGS RD
FairOver: WARM SPRINGS CREEK
10.9 MI W JCT RCKPLE RD, Sonoma, CA
Built 1978 Load: 24.3 t ADT: 400
LLANO ROAD
FairOver: ROSELAND CR FLD CNTL CHN
2.4 MI N JCT WITH SR 116, Sonoma, CA
Built 1970 Load: 24.3 t ADT: 3,000
GROVE RD
FairOver: CARRIGER CREEK
1.7 MI W JCT ARNOLD RD, Sonoma, CA
Built 1960 Load: 24.3 t ADT: 1,850
HYDE ROAD
FairOver: ARROYO SECO
0.4 MI S JCT NAPA RD, Sonoma, CA
Built 1965 Load: 24.3 t ADT: 400
REDWOOD ROAD
FairOver: HINEBAUGH CREEK
0.3 MI N ROHNERT PK EXPWY, Sonoma, CA
Built 1970 Load: 24.3 t ADT: 4,000
BETHARDS DRIVE
FairOver: MATANZAS CREEK
BET TECHEVAH & YULUPA AV, Sonoma, CA
Built 1966 Load: 24.3 t ADT: 6,000
APACHE STREET
FairOver: PAULIN CREEK
0.1 MI N OF STEELE LANE, Sonoma, CA
Built 1964 Load: 24.3 t ADT: 2,000
CHANATE ROAD
FairOver: PAULIN CREEK
NEAR MENDOCINO AVENUE, Sonoma, CA
Built 1965 Load: 24.3 t ADT: 17,942
MADISON STREET
FairOver: WASHINGTON CREEK
NORTH OF HOLLY LANE, Sonoma, CA
Built 1970 Load: 24.3 t ADT: 300
HARNEY DRIVE
FairOver: SONOMA CREEK
SONOMA STATE INSTITUTION, Sonoma, CA
Built 1935 Load: 24.3 t ADT: 250
GUERNEVILLE RD
FairOver: LAGUNA DE SANTA ROSA
1.8 MI E/O SR 116, Sonoma, CA
Built 1957 Load: 24.6 t ADT: 8,400
NEELEY ROAD
FairOver: HILLSIDE
1 MI W SR 116, Sonoma, CA
Built 2006 Load: 24.6 t ADT: 3,000
STATE ROUTE 12 WB
FairOver: NWP RR
04-SON-012-R15.56-SRO, Sonoma, CA
Built 1964 Load: 24.9 t ADT: 36,500
WEST OLIVE ST
FairOver: SANTA ROSA CREEK
WEST OLIVE ST, Sonoma, CA
Built 1962 Load: 24.9 t ADT: 8,200
PRESSLEY RD
FairOver: COPELAND CREEK
0.1 MI N LICHAU RD, Sonoma, CA
Built 1968 Load: 24.9 t ADT: 1,000
D STREET
FairOver: PETALUMA RIVER
NEAR DOWNTOWN PETALUMA, Sonoma, CA
Built 1933 Load: 25.3 t ADT: 16,330
BOHAN DILLON RD
FairOver: SOUTH FORK GUALALA RIVER
0.8 MI N FORT ROSS RD, Sonoma, CA
Built 1971 Load: 25.3 t ADT: 50
CORONA RD
FairOver: U.S. HIGHWAY 101
04-SON-101-6.83-PET, Sonoma, CA
Built 1955 Load: 25.6 t ADT: 6,500
GRANDVIEW RD
FairOver: JONIVE CREEK
0.05 MI N BODEGA HWY, Sonoma, CA
Built 1956 Load: 25.6 t ADT: 800
STWRT PT-SKGG SPRG
FairOver: DRY CREEK (BOARD BR)
AT DAM-END DRY CREEK RD, Sonoma, CA
Built 1951 Load: 25.6 t ADT: 2,800
MISSION BLVD
FairOver: SANTA ROSA CREEK
0.1 MI S SONOMA HWY SR 12, Sonoma, CA
Built 1956 Load: 25.6 t ADT: 20,000
Old Monte Rio Road
FairOver: HILLSIDE
0.6 MILE S SR 116, Sonoma, CA
Built 1996 Load: 25.6 t ADT: 100
GEYSERS RD
FairOver: HILLSIDE
0.1 MI E/O BIG SULPHUR CR, Sonoma, CA
Built 1999 Load: 25.6 t ADT: 150
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.