County profile · official public datasets

Larimer County, CO

559 public highway bridges tracked in the FHWA National Bridge Inventory: 49% rated Good, 49% Fair, 2% Poor.

Compiled by PlainBridges

559
Public bridges: 49%
Good condition: 2%
Poor condition

The verdict

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

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

Top 25%
lowest Poor share in state: 2%
Poor-condition share: 559
public highway bridges: 1987
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.

Larimer County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Larimer County ranks #16 of 64 Colorado counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 2%). Larimer County, Colorado contains 559 public highway bridges. Roughly 49% are rated “Good,” 49% “Fair,” and 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

559

Public highway bridges in Larimer County

Good condition

49%

274 of 559 rated 7-9

Fair condition

49%

274 of 559 rated 5-6

Poor condition

11 of 559 rated 4 or below

In-state Poor-share rank

#16 of 64

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

Condition distribution

Share of 559 NBI-tracked bridges by lowest applicable component rating.

Good

49% (274)

Fair

49% (274)

Poor

2% (11)

Larimer County's Poor-condition bridges carry 57,230 vehicle crossings a day

That is 1.4% of the county's reported daily bridge traffic on 2% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 5,203 crossings a day against 8,152 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 557 of 559 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

28.8% of Larimer County's bridges have passed the 50-year mark

161 of the 559 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 49% 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 33.2% of the county's Poor-condition bridge traffic

SH 392 ML over CACHE LA POUDRE RIVER, built 1959, carries 19,000 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 11-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 57,230 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

1
1910s

2
1920s

7
1930s

19
1940s

12
1950s

29
1960s

76
1970s

48
1980s

102
1990s

58
2000s

78
2010s

99
2020s

28

What this shows Construction peaked in the 1980s, when 102 of the county's bridges still in the inventory were built, which is 18.2% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year is 1987, 5 years newer than the Colorado average of 1982.

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

The 5 Colorado counties nearest Larimer County in number of bridges, with their condition splits. Its 2% Poor share is the 2nd-lowest of these 6. Its average build year of 1987 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 Larimer County and the 5 Colorado counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
El Paso County	686	31.3%	65.5%	3.2%	1984
Weld County	614	36.8%	58.5%	4.7%	1986
Larimer County (this page)	559	49%	49%	2%	1987
Adams County	535	43.9%	49.2%	6.9%	1990
Jefferson County	464	33.8%	59.9%	6.3%	1984
Denver County	458	41.9%	56.3%	1.7%	1991

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

Similar inventory size

Nearest county inventories outside CO (559 bridges here).

Chautauqua County, NY · 559 bridges
Yakima County, WA · 558 bridges
Pottawattamie County, IA · 557 bridges
Shawnee County, KS · 563 bridges

Similar average build year

Nearest mean year-built outside CO (1987 here).

St. Louis County, MO · avg 1987 · 912 bridges
Ellis County, TX · avg 1987 · 691 bridges
St. Louis County, MN · avg 1987 · 663 bridges
Palm Beach County, FL · avg 1987 · 610 bridges

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

All 559 Good 274 Fair 274 Poor 11

All bridges (559)

Sort:

Larimer County Bridge Snapshot

Condition distribution

Larimer County's Poor-condition bridges carry 57,230 vehicle crossings a day

28.8% of Larimer County's bridges have passed the 50-year mark

One structure carries 33.2% of the county's Poor-condition bridge traffic

How Larimer 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

All bridges (559)

US 287 ML

US 34 ML

I 25 ML NBND

Park Drive

PROSPECT ROAD

SH 402 ML

N Lemay Ave & BNSF

County Rd 25E

County Rd 3

County Road 18E

COUNTY RD. 10E

SH 14 ML

Railroad Avenue

US 34 ML

US 34 ML

I 25 ML NBND

I 25 ML SBND

Boise Avenue

Stage Coach

County Road 47

Remington Street

US 34 ML

County Road 52E

County Rd 43

County Rd 43

County Rd 43

County Rd 43

West Creek Road

West Creek Road

West Creek Road

Sycamore Street

County Road 15

County Road 11

County Road 27

County Road 56

County Road 17

County Road 27

US 287 ML

SH 14 ML

Centerra Parkway

Riverside Drive

I 25 ML NB+SB+SR

Third Street

Redwood Street

Access Road

Moodie Street

County Road 70

County Road 38E

Centre Street

LaPorte Avenue

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