County profile · official public datasets

Los Angeles County, CA

3,547 public highway bridges tracked in the FHWA National Bridge Inventory: 61.4% rated Good, 35.2% Fair, 3.4% Poor.

3,547
Public bridges: 61.4%
Good condition: 3.4%
Poor condition

The verdict

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

Los Angeles County posts a top-quartile lowest Poor-condition share among rated counties in the state across large county bridge inventory.

Top 12%
lowest Poor share in state: 3.4%
Poor-condition share: 3,547
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.

Los Angeles County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Los Angeles County ranks #7 of 58 California counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 3.4%). Los Angeles County, California contains 3,547 public highway bridges. Roughly 61.4% are rated “Good,” 35.2% “Fair,” and 3.4% “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

3,547

Public highway bridges in Los Angeles County

Good condition

61.4%

2,178 of 3,547 rated 7-9

Fair condition

35.2%

1,249 of 3,547 rated 5-6

Poor condition

3.4%

120 of 3,547 rated 4 or below

In-state Poor-share rank

#7 of 58

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

Condition distribution

Share of 3,547 NBI-tracked bridges by lowest applicable component rating.

Good

61.4% (2,178)

Fair

35.2% (1,249)

Poor

3.4% (120)

Los Angeles County's Poor-condition bridges carry 5,072,144 vehicle crossings a day

That is 2.2% of the county's reported daily bridge traffic on 3.4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 42,268 crossings a day against 63,853 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 3,547 of 3,547 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

75.7% of Los Angeles County's bridges have passed the 50-year mark

2,685 of the 3,547 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 61.4% 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 5.9% of the county's Poor-condition bridge traffic

INTERSTATE 110 over SLAUSON AVE & BNSF RY, built 1996, carries 300,000 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 120-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 5,072,144 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

7
1910s

13
1920s

80
1930s

168
1940s

163
1950s

685
1960s

1,137
1970s

632
1980s

229
1990s

219
2000s

117
2010s

78
2020s

19

What this shows Construction peaked in the 1960s, when 1,137 of the county's bridges still in the inventory were built, which is 32.1% 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 Los Angeles County compares with California's closest counties by inventory size

The 5 California counties nearest Los Angeles County in number of bridges, with their condition splits. Its 3.4% Poor share is the 4th-lowest of these 6. Its average build year of 1967 against a peer-group mean of 1976 is 9 years older.

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

Bridge inventory size and condition shares for Los Angeles County and the 5 California counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Los Angeles County (this page)	3,547	61.4%	35.2%	3.4%	1967
San Diego County	1,632	52.8%	44.2%	3.1%	1977
San Bernardino County	1,422	41.9%	52.1%	6%	1975
Orange County	1,164	53.2%	43.8%	3%	1978
Riverside County	1,117	56.4%	41.2%	2.4%	1977
Santa Clara County	964	38.3%	56.1%	5.6%	1972

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

Similar inventory size

Nearest county inventories outside CA (3,547 bridges here).

Dallas County, TX · 3,230 bridges
Harris County, TX · 4,029 bridges
Maricopa County, AZ · 2,847 bridges
Tarrant County, TX · 2,617 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 3,547 Good 2,178 Fair 1,249 Poor 120

All bridges (3,547)

Sort:

Los Angeles County Bridge Snapshot

Condition distribution

Los Angeles County's Poor-condition bridges carry 5,072,144 vehicle crossings a day

75.7% of Los Angeles County's bridges have passed the 50-year mark

One structure carries 5.9% of the county's Poor-condition bridge traffic

How Los Angeles 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 (3,547)

FIRST ST

VIA PRINCESSA

THE OLD RD

DESERT RD

NATIONAL BLVD

VALLEY BLVD

WORKMAN MILL RD

SIERRA OAK TRAIL

THE OLD RD

CASTAIC RD

AVE O

UNION ST

GREEN ST

NEWHALL AVE

Baseline Road

SIX STREET

CORRAL CANYON

Ramona Street

Mission Road

Del Mar Ave.

San Gabriel Blvd

RIVERSIDE DRIVE

ROUTE 187

Valencia Blvd

Valencia Blvd

DEL MAR AVE

MULHOLLAND HWY

LOST CANYON RD

VALLEY BLVD

CHANTRY FLAT ROAD

INTERSTATE 10 EB

INTERSTATE 10 WB

INTERSTATE 10 WB

INTERSTATE 10 EB

INTERSTATE 10

INTERSTATE 10

INTERSTATE 10

INTERSTATE 405

INTERSTATE 405

S405-IMPERIAL HWY

IMPERIAL HWY-N405

U.S. HIGHWAY 101

INTERSTATE 405

INTERSTATE 405

E10-N405 CONN

ALAMEDA ST-E91 ON

W91-ARTESIA+SAN FE

GRAND AVE

STATE ROUTE 1

STATE ROUTE 134

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