County profile · official public datasets

San Joaquin County, CA

644 public highway bridges tracked in the FHWA National Bridge Inventory: 33.7% rated Good, 57.1% Fair, 9.2% Poor.

644
Public bridges: 33.7%
Good condition: 9.2%
Poor condition

The verdict

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

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

42nd
of 58 on Poor share: 9.2%
Poor-condition share: 644
public highway bridges: 1968
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 Joaquin County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, San Joaquin County ranks #42 of 58 California counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 9.2%). San Joaquin County, California contains 644 public highway bridges. Roughly 33.7% are rated “Good,” 57.1% “Fair,” and 9.2% “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

644

Public highway bridges in San Joaquin County

Good condition

33.7%

217 of 644 rated 7-9

Fair condition

57.1%

368 of 644 rated 5-6

Poor condition

9.2%

59 of 644 rated 4 or below

In-state Poor-share rank

#42 of 58

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

Condition distribution

Share of 644 NBI-tracked bridges by lowest applicable component rating.

Good

33.7% (217)

Fair

57.1% (368)

Poor

9.2% (59)

San Joaquin County's Poor-condition bridges carry 1,143,289 vehicle crossings a day

That is 9.9% of the county's reported daily bridge traffic on 9.2% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 19,378 crossings a day against 12,721 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 644 of 644 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

74.8% of San Joaquin County's bridges have passed the 50-year mark

482 of the 644 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 33.7% 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 9.9% of the county's Poor-condition bridge traffic

INTERSTATE 5 SB over WEBER PERSHING FREMONT, built 1972, carries 113,000 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 59-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 1,143,289 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

1
1910s

3
1920s

31
1930s

26
1940s

27
1950s

60
1960s

169
1970s

208
1980s

35
1990s

30
2000s

23
2010s

28
2020s

3

What this shows Construction peaked in the 1970s, when 208 of the county's bridges still in the inventory were built, which is 32.3% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1968) matches the California average (1970).

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

The 5 California counties nearest San Joaquin County in number of bridges, with their condition splits. Its 9.2% Poor share is the 4th-lowest of these 6. Its average build year of 1968 against a peer-group mean of 1970 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 Joaquin County and the 5 California counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Kern County	668	50.1%	43.3%	6.6%	1972
Alameda County	658	35.3%	55.2%	9.6%	1973
San Joaquin County (this page)	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
Tulare County	589	42.4%	54.2%	3.4%	1959

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

Similar inventory size

Nearest county inventories outside CA (644 bridges here).

Mohave County, AZ · 641 bridges
Will County, IL · 649 bridges
Spartanburg County, SC · 638 bridges
Greenville County, SC · 635 bridges

Similar average build year

Nearest mean year-built outside CA (1968 here).

Montgomery County, PA · avg 1968 · 828 bridges
Providence County, RI · avg 1968 · 476 bridges
Delaware County, PA · avg 1968 · 387 bridges
Genesee County, MI · avg 1968 · 371 bridges

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

All 644 Good 217 Fair 368 Poor 59

Fair-condition bridges (368)

Sort:

San Joaquin County Bridge Snapshot

Condition distribution

San Joaquin County's Poor-condition bridges carry 1,143,289 vehicle crossings a day

74.8% of San Joaquin County's bridges have passed the 50-year mark

One structure carries 9.9% of the county's Poor-condition bridge traffic

How San Joaquin 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 (368)

CARROLTON RD

MILTON ROAD

KOSTER RD

INTERSTATE 5

BNSF WORTH SCOTTS

MILTON ROAD

SEXTON RD

KOSTER RD

BOLLEA ROAD

UP RR BNSF RY

GAWNE ROAD

MESSICK ROAD

HENRY RD

VAN ALLEN RD

CARROLTON ROAD

INTERSTATE 5 NB

LAMMERS ROAD

EIGHT MILE ROAD

WOODSON ROAD

LODI AVE

KOSTER ROAD

THORNTON ROAD

CORD ROAD

LONE TREE RD

MACARTHUR DRIVE

ESCALON-BELLOTA RD

CORRAL HOLLOW ROAD

TRACY BOULEVARD

BIRD ROAD OC

INTERSTATE 5

INTERSTATE 5

CALIFORNIA AVE

VAN ALLEN ROAD

THORNTON ROAD

PATTERSON PASS RD

INTERSTATE 5 NB

VAN ALLEN RD

STATE ROUTE 99 NB

INTERSTATE 205

INTERSTATE 580 EB

INTERSTATE 5 SB

INTERSTATE 5

STATE ROUTE 99 SB

RIO BLANCO ROAD

MANTHEY ROAD

INTERSTATE 5 SB

HAM LANE

TRACY BLVD

INTERSTATE 5 SB

STATE ROUTE 120

Related