County profile · official public datasets

Contra Costa County, CA

618 public highway bridges tracked in the FHWA National Bridge Inventory: 42.6% rated Good, 46.9% Fair, 10.5% Poor.

618
Public bridges: 42.6%
Good condition: 10.5%
Poor condition

The verdict

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

Contra Costa County pairs a higher-than-median Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

47th
of 58 on Poor share: 10.5%
Poor-condition share: 618
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.

Contra Costa County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Contra Costa County ranks #47 of 58 California counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 10.5%). Contra Costa County, California contains 618 public highway bridges. Roughly 42.6% are rated “Good,” 46.9% “Fair,” and 10.5% “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

618

Public highway bridges in Contra Costa County

Good condition

42.6%

263 of 618 rated 7-9

Fair condition

46.9%

290 of 618 rated 5-6

Poor condition

10.5%

65 of 618 rated 4 or below

In-state Poor-share rank

#47 of 58

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

Condition distribution

Share of 618 NBI-tracked bridges by lowest applicable component rating.

Good

42.6% (263)

Fair

46.9% (290)

Poor

10.5% (65)

Contra Costa County's Poor-condition bridges carry 3,873,956 vehicle crossings a day

That is 19.5% of the county's reported daily bridge traffic on 10.4% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 60,531 crossings a day against 28,273 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 617 of 618 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

51.8% of Contra Costa County's bridges have passed the 50-year mark

320 of the 618 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 42.6% 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 6.1% of the county's Poor-condition bridge traffic

INTERSTATE 680 over MONUMENT BOULEVARD, built 1998, carries 235,000 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 65-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 3,873,956 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1910s

2
1920s

9
1930s

18
1940s

18
1950s

82
1960s

132
1970s

100
1980s

57
1990s

94
2000s

57
2010s

46
2020s

3

What this shows Construction peaked in the 1960s, when 132 of the county's bridges still in the inventory were built, which is 21.4% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1977, 7 years newer than the California average of 1970.

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

The 5 California counties nearest Contra Costa County in number of bridges, with their condition splits. Its 10.5% Poor share is the 6th-lowest of these 6. Its average build year of 1977 against a peer-group mean of 1968 is 9 years newer.

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

Bridge inventory size and condition shares for Contra Costa 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	644	33.7%	57.1%	9.2%	1968
Contra Costa County (this page)	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 Contra Costa 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 Contra Costa County, both outside California so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside CA (618 bridges here).

Brazoria County, TX · 618 bridges
Westmoreland County, PA · 620 bridges
Monroe County, NY · 615 bridges
Weld County, CO · 614 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 618 Good 263 Fair 290 Poor 65

Fair-condition bridges (290)

Sort:

Contra Costa County Bridge Snapshot

Condition distribution

Contra Costa County's Poor-condition bridges carry 3,873,956 vehicle crossings a day

51.8% of Contra Costa County's bridges have passed the 50-year mark

One structure carries 6.1% of the county's Poor-condition bridge traffic

How Contra Costa 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 (290)

CAMINO RAMON

PARAISO DR

KINNEY BLVD

STATE ROUTE 24 WB

MILANO WAY

STATE ROUTE 24

STONE VALLEY RD

WHITE ROAD

WHITE ROAD

BEAR CREEK RD

STATE ROUTE 24

INTERSTATE 680 NB

VIKING DR

STATE ROUTE 24

STATE ROUTE 4

STATE ROUTE 24

STATE ROUTE 4 WB

EL CAPITAN DR

OLIVERA ROAD

SR 160 NB

STATE ROUTE 4 WB

EAST PORTAL BLDG

IMHOFF ROAD

STATE ROUTE 4 EB

MORAGA BLVD

INTERSTATE 80

W4-W80 CONNECTOR

E4-E80 CONNECTOR

SR 160 NB

S 242 ON RAMP

STATE ROUTE 4 WB

SR 160 SB

INTERSTATE 80

W80-BARRETT OFFRMP

GREENBROOK DR

N680-DIABLO RD OFF

STATE ROUTE 4 EB

E24 & ACALANES RD

STATE ROUTE 4

INTERSTATE 80

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