County profile · official public datasets

San Diego County, CA

1,632 public highway bridges tracked in the FHWA National Bridge Inventory: 52.8% rated Good, 44.2% Fair, 3.1% Poor.

1,632
Public bridges: 52.8%
Good condition: 3.1%
Poor condition

The verdict

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

San Diego County pairs a top-10% lowest Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

Top 9%
lowest Poor share in state: 3.1%
Poor-condition share: 1,632
public highway bridges: 1977
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.

San Diego County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, San Diego County ranks #5 of 58 California counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 3.1%). San Diego County, California contains 1,632 public highway bridges. Roughly 52.8% are rated “Good,” 44.2% “Fair,” and 3.1% “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

1,632

Public highway bridges in San Diego County

Good condition

52.8%

861 of 1,632 rated 7-9

Fair condition

44.2%

721 of 1,632 rated 5-6

Poor condition

3.1%

50 of 1,632 rated 4 or below

In-state Poor-share rank

#5 of 58

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

Condition distribution

Share of 1,632 NBI-tracked bridges by lowest applicable component rating.

Good

52.8% (861)

Fair

44.2% (721)

Poor

3.1% (50)

San Diego County's Poor-condition bridges carry 1,808,795 vehicle crossings a day

That is 3.2% of the county's reported daily bridge traffic on 3.1% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 36,176 crossings a day against 29,200 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 1,632 of 1,632 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

51.3% of San Diego County's bridges have passed the 50-year mark

838 of the 1,632 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 52.8% 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 13.8% of the county's Poor-condition bridge traffic

INTERSTATE 805 over TELEGRAPH CANYON DRAIN, built 1971, carries 250,000 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 50-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 1,808,795 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

2
1910s

5
1920s

16
1930s

29
1940s

59
1950s

110
1960s

361
1970s

410
1980s

203
1990s

169
2000s

164
2010s

91
2020s

13

What this shows Construction peaked in the 1970s, when 410 of the county's bridges still in the inventory were built, which is 25.1% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year is 1977, 7 years newer than the California average of 1970.

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

The 5 California counties nearest San Diego County in number of bridges, with their condition splits. Its 3.1% Poor share is the 3rd-lowest of these 6. Its average build year of 1977 against a peer-group mean of 1974 is in line with the group.

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

Bridge inventory size and condition shares for San Diego County and the 5 California counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
San Diego County (this page)	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
Fresno County	916	38.9%	57.3%	3.8%	1969

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

Similar inventory size

Nearest county inventories outside CA (1,632 bridges here).

Travis County, TX · 1,544 bridges
Cook County, IL · 1,721 bridges
Sedgwick County, KS · 1,333 bridges
Allegheny County, PA · 1,294 bridges

Similar average build year

Nearest mean year-built outside CA (1977 here).

King County, WA · avg 1977 · 1,238 bridges
Shelby County, TN · avg 1977 · 1,077 bridges
Chautauqua County, NY · avg 1977 · 559 bridges
St. Clair County, IL · avg 1977 · 486 bridges

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

All 1,632 Good 861 Fair 721 Poor 50

Fair-condition bridges (721)

Sort:

San Diego County Bridge Snapshot

Condition distribution

San Diego County's Poor-condition bridges carry 1,808,795 vehicle crossings a day

51.3% of San Diego County's bridges have passed the 50-year mark

One structure carries 13.8% of the county's Poor-condition bridge traffic

How San Diego 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

Fair-condition bridges (721)

S 38TH STREET

HOME AV-W94 ONRAMP

CRISTIANITOS ROAD

N805-MIRA MESA OFF

INTERSTATE 15 SB

INTERSTATE 905 WB

INTERSTATE 905 WB

INTERSTATE 5

INTERSTATE 8 WB

PACIFIC HWY

WILDWOOD GLEN LN

STATE ROUTE 67 SB

INTERSTATE 8 EB

S-15 ONRAMP

HARMONY GROVE RD

PARK BLVD

STATE ROUTE 78 WB

STATE ROUTE 78 EB

INTERSTATE 5 SB

INTERSTATE 5 NB

INTERSTATE 805

INTERSTATE 15 SB

NATIONAL AVE

BROADWAY

MAIN-N15 ON RAMP

INTERSTATE 805 SB

VOIGT DRIVE

INTERSTATE 805

TULIP ST

REGENTS ROAD

1ST AV-N5 ON-RAMP

S163-S5 CONNECTOR

INTERSTATE 5

INTERSTATE 5

INTERSTATE 5

PALM AVENUE

INTERSTATE 15 NB

OLD HIGHWAY 395

THIRD AVENUE

N805-MIRA MESA OFF

DOUGLAS DR

INTERSTATE 5 SB

INTERSTATE 5 NB

STATE ROUTE 94 WB

INTERSTATE 5

INTERSTATE 905 WB

INTERSTATE 905 EB

SUNSET DRIVE

OLD CASTLE RD

INTERSTATE 5

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