County profile · official public datasets

Orange County, CA

1,164 public highway bridges tracked in the FHWA National Bridge Inventory: 53.2% rated Good, 43.8% Fair, 3% Poor.

1,164
Public bridges: 53.2%
Good condition: 3%
Poor condition

The verdict

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

Orange County pairs a top-5% lowest Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

Top 5%
lowest Poor share in state: 3%
Poor-condition share: 1,164
public highway bridges: 1978
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.

Orange County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Orange County ranks #3 of 58 California counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 3%). Orange County, California contains 1,164 public highway bridges. Roughly 53.2% are rated “Good,” 43.8% “Fair,” and 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.

Total bridges

1,164

Public highway bridges in Orange County

Good condition

53.2%

619 of 1,164 rated 7-9

Fair condition

43.8%

510 of 1,164 rated 5-6

Poor condition

35 of 1,164 rated 4 or below

In-state Poor-share rank

#3 of 58

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

Condition distribution

Share of 1,164 NBI-tracked bridges by lowest applicable component rating.

Good

53.2% (619)

Fair

43.8% (510)

Poor

3% (35)

Orange County's Poor-condition bridges carry 1,431,765 vehicle crossings a day

That is 2.3% of the county's reported daily bridge traffic on 3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 40,908 crossings a day against 57,201 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 1,164 of 1,164 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

48.9% of Orange County's bridges have passed the 50-year mark

569 of the 1,164 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 53.2% 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 16% of the county's Poor-condition bridge traffic

STATE ROUTE 57 over BNSF RY AMTRAK METROLINK, built 1976, carries 229,000 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 35-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 1,431,765 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1910s

2
1920s

12
1930s

21
1940s

14
1950s

114
1960s

284
1970s

191
1980s

105
1990s

277
2000s

99
2010s

39
2020s

6

What this shows Construction peaked in the 1960s, when 284 of the county's bridges still in the inventory were built, which is 24.4% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1978, 8 years newer than the California average of 1970.

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

The 5 California counties nearest Orange County in number of bridges, with their condition splits. Its 3% Poor share is the 2nd-lowest of these 6. Its average build year of 1978 against a peer-group mean of 1973 is 5 years newer.

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

Bridge inventory size and condition shares for Orange County and the 5 California counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
San Bernardino County	1,422	41.9%	52.1%	6%	1975
Orange County (this page)	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
Fresno County	916	38.9%	57.3%	3.8%	1969
Sacramento County	740	50.9%	45.7%	3.4%	1973

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

Similar inventory size

Nearest county inventories outside CA (1,164 bridges here).

Williamson County, TX · 1,170 bridges
Pima County, AZ · 1,150 bridges
Clark County, NV · 1,141 bridges
Tulsa County, OK · 1,135 bridges

Similar average build year

Nearest mean year-built outside CA (1978 here).

Sumner County, KS · avg 1978 · 659 bridges
Allen County, IN · avg 1978 · 613 bridges
Livingston County, IL · avg 1978 · 579 bridges
Buncombe County, NC · avg 1978 · 555 bridges

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

All 1,164 Good 619 Fair 510 Poor 35

Good-condition bridges (619)

Sort:

Orange County Bridge Snapshot

Condition distribution

Orange County's Poor-condition bridges carry 1,431,765 vehicle crossings a day

48.9% of Orange County's bridges have passed the 50-year mark

One structure carries 16% of the county's Poor-condition bridge traffic

How Orange 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 (619)

W22 ON RAMP

E22 OFF RAMP

STATE ROUTE 22 EB

SR 39 (BEACH BLVD)

STATE ROUTE 91

EB 91 OFF RAMP

INTERSTATE 605

INTERSTATE 605

INTERSTATE 605 SB

INTERSTATE 605

STATE ROUTE 55

S405-N55 CONNECTOR

N405-S55 CONN RAMP

BRISTOL ST

N73-N405 CONNECTOR

IRVINE CENTER DR

CROWN VALLEY PKWY

E91-N57 CONNECTOR

INTERSTATE 405

STATE ROUTE 57

STATE ROUTE 57

INTERSTATE 405

STATE ROUTE 57

STATE ROUTE 57

N&S605-N405 CONN

LAKEVIEW AVE

INTERSTATE 405

INTERSTATE 405

INTERSTATE 405

INTERSTATE 405

INTERSTATE 405

INTERSTATE 405

STATE ROUTE 91

STATE ROUTE 91

STATE ROUTE 91

STATE ROUTE 91

STATE ROUTE 91

STATE ROUTE 91

E. LAMBERT ON-RAMP

STATE ROUTE 55

STATE ROUTE 91 EB

E91-S5 CONN

STATE ROUTE 91 WB

INTERSTATE 405

INTERSTATE 405

INTERSTATE 405

RAMP/CONNECTOR 405

S57-ORANGETHORPE

NORTH BRISTOL ST

N55-N73 CONNECTOR

Related