County profile · official public datasets

Nevada County, CA

135 public highway bridges tracked in the FHWA National Bridge Inventory: 45.2% rated Good, 40.7% Fair, 14.1% Poor.

135
Public bridges: 45.2%
Good condition: 14.1%
Poor condition

The verdict

According to the Federal Highway Administration's 2024 National Bridge Inventory.

Nevada County posts a higher-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.

55th
of 58 on Poor share: 14.1%
Poor-condition share: 135
public highway bridges: 1972
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.

Nevada County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Nevada County ranks #55 of 58 California counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 14.1%). Nevada County, California contains 135 public highway bridges. Roughly 45.2% are rated “Good,” 40.7% “Fair,” and 14.1% “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.

Total bridges

135

Public highway bridges in Nevada County

Good condition

45.2%

61 of 135 rated 7-9

Fair condition

40.7%

55 of 135 rated 5-6

Poor condition

14.1%

19 of 135 rated 4 or below

In-state Poor-share rank

#55 of 58

Among California counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 135 NBI-tracked bridges by lowest applicable component rating.

Good

45.2% (61)

Fair

40.7% (55)

Poor

14.1% (19)

Nevada County's Poor-condition bridges carry 70,824 vehicle crossings a day

That is 5.8% of the county's reported daily bridge traffic on 14.1% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 3,728 crossings a day against 11,482 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 135 of 135 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

60.7% of Nevada County's bridges have passed the 50-year mark

82 of the 135 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 45.2% 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 17.5% of the county's Poor-condition bridge traffic

INTERSTATE 80 WB over SOUTH YUBA RIVER, built 1962, carries 12,400 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 19-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 70,824 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

pre-1900

1
1900s

2
1910s

1
1920s

7
1930s

6
1940s

1
1950s

15
1960s

40
1970s

11
1980s

12
1990s

11
2000s

22
2010s

5
2020s

1

What this shows Construction peaked in the 1960s, when 40 of the county's bridges still in the inventory were built, which is 29.6% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1972) matches the California average (1970).

How Nevada County compares with California's closest counties by inventory size

The 5 California counties nearest Nevada County in number of bridges, with their condition splits. Its 14.1% Poor share is the 5th-lowest of these 6. Its average build year of 1972 against a peer-group mean of 1968 is in line with the group.

Showing the 5 closest of 57 California counties eligible for comparison.

Bridge inventory size and condition shares for Nevada County and the 5 California counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
San Francisco County	143	34.3%	51%	14.7%	1969
Nevada County (this page)	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	125	36%	56.8%	7.2%	1964
Sutter County	121	33.9%	52.9%	13.2%	1968

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 Nevada 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 Nevada County, both outside California so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside CA (135 bridges here).

Meriwether County, GA · 135 bridges
Steuben County, IN · 135 bridges
Warren County, IN · 135 bridges
Boone County, IA · 135 bridges

Similar average build year

Nearest mean year-built outside CA (1972 here).

Madison County, AL · avg 1972 · 710 bridges
York County, PA · avg 1972 · 569 bridges
Middlesex County, NJ · avg 1972 · 563 bridges
Saunders County, NE · avg 1972 · 506 bridges

Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.

All 135 Good 61 Fair 55 Poor 19

Good-condition bridges (61)

Sort:

Nevada County Bridge Snapshot

Condition distribution

Nevada County's Poor-condition bridges carry 70,824 vehicle crossings a day

60.7% of Nevada County's bridges have passed the 50-year mark

One structure carries 17.5% of the county's Poor-condition bridge traffic

How Nevada County compares with California's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Good-condition bridges (61)

FDR 41

FDR 20-17-04

FDR 85

Boca Dam Road

FDR 18

BRUNSWICK ROAD

SOUTH PINE STREET

WEST RIVER ST

MAYBERT ROAD

STATE ROUTE 20

STATE ROUTE 49

RAIL ROAD AVENUE

FJORD RD

GARDEN BAR ROAD

EAGLE LAKE ROAD

LAKE VALLEY ROAD

GOLD FLAT ROAD

INTERSTATE 80

STATE ROUTE 20

EAGLE LAKE ROAD

INTERSTATE 80

RETRAC WAY

STATE ROUTE 20

INTERSTATE 80

INTERSTATE 80

STATE ROUTE 89

DONNER PASS ROAD

STATE ROUTE 20

INTERSTATE 80

INTERSTATE 80

INTERSTATE 80

INTERSTATE 80

STATE ROUTE 20

STATE ROUTE 20

STATE ROUTE 20

INTERSTATE 80 WB

INTERSTATE 80 EB

INTERSTATE 80

INTERSTATE 80

DOG BAR ROAD

GLENSHIRE DR

BENNETT ST

STAMPEDE MEADOWS R

VALLEY DRIVE

PURDON ROAD

SODA SPRINGS RD

INTERSTATE 80

STATE ROUTE 20

IDAHO-MARYLAND-E20

DORSEY DR

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