Total bridges
112
Public highway bridges in Belknap County
County profile · official public datasets
Belknap County, NH
112 public highway bridges tracked in the FHWA National Bridge Inventory: 58% rated Good, 37.5% Fair, 4.5% Poor.
- 112
- Public bridges
- 58%
- Good condition
- 4.5%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Belknap County posts a top-quartile lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- Top 20%
- lowest Poor share in state
- 4.5%
- Poor-condition share
- 112
- public highway bridges
- 1969
- 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.
Belknap County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Belknap County ranks #2 of 10 New Hampshire counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 4.5%). Belknap County, New Hampshire contains 112 public highway bridges. Roughly 58% are rated “Good,” 37.5% “Fair,” and 4.5% “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.
Good condition
58%
65 of 112 rated 7-9
Fair condition
37.5%
42 of 112 rated 5-6
Poor condition
4.5%
5 of 112 rated 4 or below
In-state Poor-share rank
#2 of 10
Among New Hampshire counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 112 NBI-tracked bridges by lowest applicable component rating.
Good 58% (65)
Fair 37.5% (42)
Poor 4.5% (5)
Belknap County's Poor-condition bridges carry 18,477 vehicle crossings a day
That is 3% of the county's reported daily bridge traffic on 4.5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 3,695 crossings a day against 4,380 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 112 of 112 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
62.5% of Belknap County's bridges have passed the 50-year mark
70 of the 112 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 58% 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 55.2% of the county's Poor-condition bridge traffic
NH 11 over MERRYMEETING RIVER, built 1934, carries 10,193 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 5-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 18,477 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Belknap County's bridges were built
112 bridges with a recorded construction year, grouped by decade
- 1900s 3
1900–1909
3 bridges
- 1920s 8
1920–1929
8 bridges
- 1930s 9
1930–1939
9 bridges
- 1940s 9
1940–1949
9 bridges
- 1950s 3
1950–1959
3 bridges
- 1960s
1960–1969
33 bridges
- 1970s 8
1970–1979
8 bridges
- 1980s 9
1980–1989
9 bridges
- 1990s 6
1990–1999
6 bridges
- 2000s 9
2000–2009
9 bridges
- 2010s 9
2010–2019
9 bridges
- 2020s 6
2020–2029
6 bridges
What this shows Construction peaked in the 1960s, when 33 of the county's bridges still in the inventory were built, which is 29.5% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1969) matches the New Hampshire average (1968).
How Belknap County compares with New Hampshire's closest counties by inventory size
The 5 New Hampshire counties nearest Belknap County in number of bridges, with their condition splits. Its 4.5% Poor share is the 2nd-lowest of these 6. Its average build year of 1969 against a peer-group mean of 1965 is in line with the group.
Showing the 5 closest of 9 New Hampshire counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Carroll County | 193 | 54.9% | 40.9% | 4.1% | 1966 |
| Cheshire County | 192 | 41.7% | 46.9% | 11.5% | 1960 |
| Coos County | 188 | 49.5% | 44.1% | 6.4% | 1964 |
| Sullivan County | 158 | 45.6% | 49.4% | 5.1% | 1963 |
| Strafford County | 136 | 63.2% | 27.9% | 8.8% | 1971 |
| Belknap County (this page) | 112 | 58% | 37.5% | 4.5% | 1969 |
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 Belknap 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 Belknap County, both outside New Hampshire so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside NH (112 bridges here).
- Columbia County, FL · 112 bridges
- Sumter County, FL · 112 bridges
- Houston County, GA · 112 bridges
- Tift County, GA · 112 bridges
Similar average build year
Nearest mean year-built outside NH (1969 here).
- Cook County, IL · avg 1969 · 1,721 bridges
- Fresno County, CA · avg 1969 · 916 bridges
- Cuyahoga County, OH · avg 1969 · 871 bridges
- Ventura County, CA · avg 1969 · 501 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Poor-condition bridges (5)
CENTENARY AVENUE
PoorOver: NHRR
TOWN RD, Belknap, NH
Built 1940 Load: 8.0 t ADT: 90
NH 11B
PoorOver: GUNSTOCK RIVER
0.6 MI N JCT NH 11-A, Belknap, NH
Built 1941 Load: 26.5 t ADT: 2,650
NH 11
PoorOver: MERRYMEETING RIVER
8.5 MI FROM GILFORD TL, Belknap, NH
Built 1934 Load: 30.6 t ADT: 10,193
NH 11
PoorOver: POOR FARM BROOK
1.7 MI S ALTON TL, Belknap, NH
Built 1966 Load: 37.2 t ADT: 5,454
BROOK ROAD
PoorOver: SALMON BROOK
0.1 MI FROM HALE RD, Belknap, NH
Built 1900 Load: 45.4 t ADT: 90
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.