Total bridges
13
Public highway bridges in San Juan County
County profile · official public datasets
San Juan County, CO
13 public highway bridges tracked in the FHWA National Bridge Inventory: 53.8% rated Good, 38.5% Fair, 7.7% Poor.
- 13
- Public bridges
- 53.8%
- Good condition
- 7.7%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
San Juan County posts a higher-than-median Poor-condition share among rated counties in the state across rated county bridge inventory.
- 55th
- of 64 on Poor share
- 7.7%
- Poor-condition share
- 13
- public highway bridges
- 1981
- 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 Juan County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, San Juan County ranks #55 of 64 Colorado counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 7.7%). San Juan County, Colorado contains 13 public highway bridges. Roughly 53.8% are rated “Good,” 38.5% “Fair,” and 7.7% “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.
Good condition
53.8%
7 of 13 rated 7-9
Fair condition
38.5%
5 of 13 rated 5-6
Poor condition
7.7%
1 of 13 rated 4 or below
In-state Poor-share rank
#55 of 64
Among Colorado counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 13 NBI-tracked bridges by lowest applicable component rating.
Good 53.8% (7)
Fair 38.5% (5)
Poor 7.7% (1)
San Juan County's Poor-condition bridges carry 647 vehicle crossings a day
That is 8.3% of the county's reported daily bridge traffic on 7.7% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 647 crossings a day against 548 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 13 of 13 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
23.1% of San Juan County's bridges have passed the 50-year mark
3 of the 13 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 53.8% 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 100% of the county's Poor-condition bridge traffic
GREENE STREET over CEMENT CREEK, built 1929, carries 647 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 1-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 647 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When San Juan County's bridges were built
13 bridges with a recorded construction year, grouped by decade
- 1920s 1
1920–1929
1 bridges
- 1930s 1
1930–1939
1 bridges
- 1940s 1
1940–1949
1 bridges
- 1980s
1980–1989
4 bridges
- 1990s
1990–1999
4 bridges
- 2010s
2010–2019
2 bridges
What this shows Construction peaked in the 1980s, when 4 of the county's bridges still in the inventory were built, which is 30.8% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year (1981) matches the Colorado average (1982).
How San Juan County compares with Colorado's closest counties by inventory size
The 5 Colorado counties nearest San Juan County in number of bridges, with their condition splits. Its 7.7% Poor share is the 5th-lowest of these 6. Its average build year of 1981 against a peer-group mean of 1980 is in line with the group.
Showing the 5 closest of 63 Colorado counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Mineral County | 26 | 34.6% | 65.4% | 0% | 1973 |
| Custer County | 20 | 45% | 50% | 5% | 1972 |
| Gilpin County | 19 | 10.5% | 89.5% | 0% | 1984 |
| Lake County | 17 | 52.9% | 35.3% | 11.8% | 1985 |
| Alamosa County | 16 | 37.5% | 62.5% | 0% | 1985 |
| San Juan County (this page) | 13 | 53.8% | 38.5% | 7.7% | 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 San Juan 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 Juan County, both outside Colorado so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside CO (13 bridges here).
- Bethel County, AK · 13 bridges
- Perkins County, NE · 13 bridges
- Wheeler County, NE · 13 bridges
- Harding County, NM · 13 bridges
Similar average build year
Nearest mean year-built outside CO (1981 here).
- Franklin County, OH · avg 1981 · 922 bridges
- Greenville County, SC · avg 1981 · 635 bridges
- Montgomery County, OH · avg 1981 · 632 bridges
- McLean County, IL · avg 1981 · 624 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Poor-condition bridges (1)
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges
Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.