County profile · official public datasets

Sullivan County, NH

158 public highway bridges tracked in the FHWA National Bridge Inventory: 45.6% rated Good, 49.4% Fair, 5.1% Poor.

158
Public bridges: 45.6%
Good condition: 5.1%
Poor condition

The verdict

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

Sullivan County pairs a better-than-median Poor-condition share among rated counties in the state with an older average build year than the state inventory.

Top 30%
lowest Poor share in state: 5.1%
Poor-condition share: 158
public highway bridges: 1963
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.

Sullivan County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Sullivan County ranks #3 of 10 New Hampshire counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 5.1%). Sullivan County, New Hampshire contains 158 public highway bridges. Roughly 45.6% are rated “Good,” 49.4% “Fair,” and 5.1% “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

158

Public highway bridges in Sullivan County

Good condition

45.6%

72 of 158 rated 7-9

Fair condition

49.4%

78 of 158 rated 5-6

Poor condition

5.1%

8 of 158 rated 4 or below

In-state Poor-share rank

#3 of 10

Among New Hampshire counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 158 NBI-tracked bridges by lowest applicable component rating.

Good

45.6% (72)

Fair

49.4% (78)

Poor

5.1% (8)

Sullivan County's Poor-condition bridges carry 10,550 vehicle crossings a day

That is 2.3% of the county's reported daily bridge traffic on 5.1% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 1,319 crossings a day against 2,219 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 158 of 158 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

65.8% of Sullivan County's bridges have passed the 50-year mark

104 of the 158 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 45.6% 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 35.7% of the county's Poor-condition bridge traffic

NH 12 over NECRR, built 1959, carries 3,766 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 8-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 10,550 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

pre-1900

5
1900s

3
1910s

1
1920s

12
1930s

19
1940s

10
1950s

17
1960s

26
1970s

17
1980s

10
1990s

13
2000s

9
2010s

14
2020s

2

What this shows Construction peaked in the 1960s, when 26 of the county's bridges still in the inventory were built, which is 16.5% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1963, 5 years older than the New Hampshire average of 1968.

How Sullivan County compares with New Hampshire's closest counties by inventory size

The 5 New Hampshire counties nearest Sullivan County in number of bridges, with their condition splits. Its 5.1% Poor share is the 3rd-lowest of these 6. Its average build year of 1963 against a peer-group mean of 1966 is in line with the group.

Showing the 5 closest of 9 New Hampshire counties eligible for comparison.

Bridge inventory size and condition shares for Sullivan County and the 5 New Hampshire counties closest to it in inventory size
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 (this page)	158	45.6%	49.4%	5.1%	1963
Strafford County	136	63.2%	27.9%	8.8%	1971
Belknap County	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 Sullivan 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 Sullivan County, both outside New Hampshire so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside NH (158 bridges here).

Napa County, CA · 158 bridges
Wells County, IN · 158 bridges
Jackson County, MI · 158 bridges
Yalobusha County, MS · 158 bridges

Similar average build year

Nearest mean year-built outside NH (1963 here).

Worcester County, MA · avg 1963 · 1,014 bridges
Honolulu County, HI · avg 1963 · 682 bridges
Chester County, PA · avg 1963 · 680 bridges
Essex County, NJ · avg 1963 · 505 bridges

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

All 158 Good 72 Fair 78 Poor 8

Fair-condition bridges (78)

Sort:

Sullivan County Bridge Snapshot

Condition distribution

Sullivan County's Poor-condition bridges carry 10,550 vehicle crossings a day

65.8% of Sullivan County's bridges have passed the 50-year mark

One structure carries 35.7% of the county's Poor-condition bridge traffic

How Sullivan County compares with New Hampshire'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 (78)

ROOT HILL ROAD

MUMMERY ROAD EAST

SQUAG CITY ROAD

COLBY HILL ROAD

CORBIN BRIDGE ROAD

RIVER ROAD

PLATT ROAD

CENTER ROAD

BROOK ROAD

STAGE ROAD

TANDY BROOK ROAD

NH 31

COLD POND ROAD

NEAL MINE ROAD

OLD STATE ROAD

NH 10

RED WATER BROOK RD

NH 10

CUTLER ROAD

CITIZENS STREET

NH120

MOUNTAIN ROAD

PURLING BECK ROAD

BROOK ROAD

I-89 SB

I-89 NB

COOPER STREET

I-89 SB

OLD NH 10

I-89 SB

I-89 NB

NH120

NH 12 NH103

NH 11 NH103

BERYL MT ROAD

NH 11

NH 11

RED WATER BROOK RD

WHITEWATER BK RD

NH 10

HOWE HILL ROAD

CRANE BROOK ROAD

OAK STREET

BELKNAP AVENUE

NH 11 RAMP

I-89 NB

TOWN HOUSE ROAD

WESTGATE ROAD

BALL PARK ROAD

CAMP ROAD

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