County profile · official public datasets

Jefferson County, CO

464 public highway bridges tracked in the FHWA National Bridge Inventory: 33.8% rated Good, 59.9% Fair, 6.3% Poor.

464
Public bridges: 33.8%
Good condition: 6.3%
Poor condition

The verdict

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

Jefferson County posts a higher-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.

40th
of 64 on Poor share: 6.3%
Poor-condition share: 464
public highway bridges: 1984
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.

Jefferson County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Jefferson County ranks #40 of 64 Colorado counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.3%). Jefferson County, Colorado contains 464 public highway bridges. Roughly 33.8% are rated “Good,” 59.9% “Fair,” and 6.3% “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

464

Public highway bridges in Jefferson County

Good condition

33.8%

157 of 464 rated 7-9

Fair condition

59.9%

278 of 464 rated 5-6

Poor condition

6.3%

29 of 464 rated 4 or below

In-state Poor-share rank

#40 of 64

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

Condition distribution

Share of 464 NBI-tracked bridges by lowest applicable component rating.

Good

33.8% (157)

Fair

59.9% (278)

Poor

6.3% (29)

Jefferson County's Poor-condition bridges carry 853,450 vehicle crossings a day

That is 10.1% of the county's reported daily bridge traffic on 6.3% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 29,429 crossings a day against 16,847 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 464 of 464 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

33.2% of Jefferson County's bridges have passed the 50-year mark

154 of the 464 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 33.8% 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 11.8% of the county's Poor-condition bridge traffic

US 6 ML over SH 121 ML, built 1972, carries 101,000 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 29-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 853,450 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

1
1930s

11
1940s

12
1950s

26
1960s

59
1970s

80
1980s

93
1990s

78
2000s

56
2010s

37
2020s

11

What this shows Construction peaked in the 1980s, when 93 of the county's bridges still in the inventory were built, which is 20% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year (1984) matches the Colorado average (1982).

How Jefferson County compares with Colorado's closest counties by inventory size

The 5 Colorado counties nearest Jefferson County in number of bridges, with their condition splits. Its 6.3% Poor share is the 4th-lowest of these 6. Its average build year of 1984 against a peer-group mean of 1987 is in line with the group.

Showing the 5 closest of 63 Colorado counties eligible for comparison.

Bridge inventory size and condition shares for Jefferson County and the 5 Colorado counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Larimer County	559	49%	49%	2%	1987
Adams County	535	43.9%	49.2%	6.9%	1990
Jefferson County (this page)	464	33.8%	59.9%	6.3%	1984
Denver County	458	41.9%	56.3%	1.7%	1991
Arapahoe County	391	26.1%	66.8%	7.2%	1984
Mesa County	319	35.1%	63.3%	1.6%	1981

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

Similar inventory size

Nearest county inventories outside CO (464 bridges here).

Hamilton County, TN · 464 bridges
Calcasieu County, LA · 463 bridges
Darke County, OH · 463 bridges
Anderson County, SC · 463 bridges

Similar average build year

Nearest mean year-built outside CO (1984 here).

Hennepin County, MN · avg 1984 · 936 bridges
Duval County, FL · avg 1984 · 831 bridges
Bell County, TX · avg 1984 · 660 bridges
Steuben County, NY · avg 1984 · 627 bridges

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

All 464 Good 157 Fair 278 Poor 29

Fair-condition bridges (278)

Sort:

Jefferson County Bridge Snapshot

Condition distribution

Jefferson County's Poor-condition bridges carry 853,450 vehicle crossings a day

33.2% of Jefferson County's bridges have passed the 50-year mark

One structure carries 11.8% of the county's Poor-condition bridge traffic

How Jefferson County compares with Colorado'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 (278)

SH 470 ML

US 285 ML

West Gate Road

ESTES COURT

I 70 ML WBND

KASSLER ROAD

US 6 ML

US 40 ML

NFSR 211

I 70 ML WBND

I 70 ML EBND

SH470 ML

COUNTY ROAD 74

I 70 ML EBND

US 40 ML

I 70 ML EBND

RAMP TO I 76 EBND

I 70 ML EBND

10TH STREET

SALVIA STREET

I 70 ML WBND

92ND AVENUE

67TH PLACE

SH 74 ML

I 70 ML EBND

I 70 ML EBND

MARSHALL STREET

MCINTYRE ST

I 70 ML WBND

SIMMS STREET

I 70 ML WBND

SH 121 ML

WADSWORTH BLVD

SH 8 ML

CRESTONE STREET

ROONEY ROAD

US 40 ML

I 70 ML

SH 8 ML

PIERCE STREET

COUNTY ROAD 122

I 76 WBND

I 70 ML EBND

US 6 ML

US 285 ML

7TH PLACE

US 36 ML

COUNTY ROAD 96

I 70 WB RAMP

SH 391 ML NBND

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