County profile · official public datasets

Kern County, CA

668 public highway bridges tracked in the FHWA National Bridge Inventory: 50.1% rated Good, 43.3% Fair, 6.6% Poor.

668
Public bridges: 50.1%
Good condition: 6.6%
Poor condition

The verdict

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

Kern County posts a better-than-median Poor-condition share among rated counties in the state across large county bridge inventory.

Top 47%
lowest Poor share in state: 6.6%
Poor-condition share: 668
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.

Kern County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Kern County ranks #27 of 58 California counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.6%). Kern County, California contains 668 public highway bridges. Roughly 50.1% are rated “Good,” 43.3% “Fair,” and 6.6% “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

668

Public highway bridges in Kern County

Good condition

50.1%

335 of 668 rated 7-9

Fair condition

43.3%

289 of 668 rated 5-6

Poor condition

6.6%

44 of 668 rated 4 or below

In-state Poor-share rank

#27 of 58

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

Condition distribution

Share of 668 NBI-tracked bridges by lowest applicable component rating.

Good

50.1% (335)

Fair

43.3% (289)

Poor

6.6% (44)

Kern County's Poor-condition bridges carry 468,180 vehicle crossings a day

That is 5.3% of the county's reported daily bridge traffic on 6.6% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 10,640 crossings a day against 15,153 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 668 of 668 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

67.7% of Kern County's bridges have passed the 50-year mark

452 of the 668 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 50.1% 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 11.3% of the county's Poor-condition bridge traffic

STATE ROUTE 99 over HIGH ST & UP RR, built 1955, carries 53,000 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 44-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 468,180 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1910s

5
1920s

6
1930s

19
1940s

36
1950s

81
1960s

200
1970s

139
1980s

41
1990s

39
2000s

42
2010s

52
2020s

8

What this shows Construction peaked in the 1960s, when 200 of the county's bridges still in the inventory were built, which is 29.9% 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 Kern County compares with California's closest counties by inventory size

The 5 California counties nearest Kern County in number of bridges, with their condition splits. Its 6.6% Poor share is the 2nd-lowest of these 6. Its average build year of 1972 against a peer-group mean of 1972 is in line with the group.

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

Bridge inventory size and condition shares for Kern County and the 5 California counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Sacramento County	740	50.9%	45.7%	3.4%	1973
Kern County (this page)	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	609	24.1%	69%	6.9%	1967

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

Similar inventory size

Nearest county inventories outside CA (668 bridges here).

Berks County, PA · 667 bridges
St. Louis County, MN · 663 bridges
Hinds County, MS · 663 bridges
Jefferson County, KY · 662 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 668 Good 335 Fair 289 Poor 44

All bridges (668)

Sort:

Kern County Bridge Snapshot

Condition distribution

Kern County's Poor-condition bridges carry 468,180 vehicle crossings a day

67.7% of Kern County's bridges have passed the 50-year mark

One structure carries 11.3% of the county's Poor-condition bridge traffic

How Kern 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

All bridges (668)

21ST STREET

24TH ST (OLD 178)

LERDO HIGHWAY

STATE ROUTE 155

COPUS RD

HERRING RD

ZERKER RD

OLD RIVER RD

HANAWALT AVE

MERCED AVE

SANDRINI RD

BORAX ROAD

STATE ROUTE 58

KIMBERLINA RD

STATE ROUTE 204

20 MULE TEAM ROAD

MULLER RD

N CHESTER AVE

STATE ROUTE 204

STATE ROUTE 204

SR 178

WOOLLOMES AVE

EVA DRIVE

KIMBERLINA ROAD

CALIFORNIA AVE

PANAMA LANE

ELMO HWY

BEAR MT WINERY RD

STATE ROUTE 178

MALAGA RD

HERMOSA RD

STATE ROUTE 99

STATE ROUTE 99

STATE ROUTE 99

STATE ROUTE 178

SR 178 WB

SR 178 EB

STATE ROUTE 166

GEPHART ROAD

STATE ROUTE 155

ELK HILLS ROAD

PANAMA RD

MIDWAY ROAD

S CHESTER AVE

WHITE LANE

MIL POTRERO HWY

TEHACHAPI BLVD

30TH STREET

GRAPEVINE ROAD

TERRACE WAY

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