County profile · official public datasets

Rockingham County, NH

308 public highway bridges tracked in the FHWA National Bridge Inventory: 66.6% rated Good, 26.9% Fair, 6.5% Poor.

308
Public bridges: 66.6%
Good condition: 6.5%
Poor condition

The verdict

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

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

Top 50%
lowest Poor share in state: 6.5%
Poor-condition share: 308
public highway bridges: 1977
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.

Rockingham County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Rockingham County ranks #5 of 10 New Hampshire counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.5%). Rockingham County, New Hampshire contains 308 public highway bridges. Roughly 66.6% are rated “Good,” 26.9% “Fair,” and 6.5% “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.

Total bridges

308

Public highway bridges in Rockingham County

Good condition

66.6%

205 of 308 rated 7-9

Fair condition

26.9%

83 of 308 rated 5-6

Poor condition

6.5%

20 of 308 rated 4 or below

In-state Poor-share rank

#5 of 10

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

Condition distribution

Share of 308 NBI-tracked bridges by lowest applicable component rating.

Good

66.6% (205)

Fair

26.9% (83)

Poor

6.5% (20)

Rockingham County's Poor-condition bridges carry 70,567 vehicle crossings a day

That is 1.8% of the county's reported daily bridge traffic on 6.5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 3,528 crossings a day against 14,477 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 306 of 308 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

43.2% of Rockingham County's bridges have passed the 50-year mark

133 of the 308 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 66.6% 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 22.8% of the county's Poor-condition bridge traffic

US 1 over CSX(ABD), built 1936, carries 16,112 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 20-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 70,567 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

pre-1900

1
1900s

3
1910s

2
1920s

12
1930s

32
1940s

14
1950s

9
1960s

30
1970s

47
1980s

35
1990s

43
2000s

33
2010s

41
2020s

6

What this shows Construction peaked in the 1970s, when 47 of the county's bridges still in the inventory were built, which is 15.3% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year is 1977, 9 years newer than the New Hampshire average of 1968.

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

The 5 New Hampshire counties nearest Rockingham County in number of bridges, with their condition splits. Its 6.5% Poor share is the 3rd-lowest of these 6. Its average build year of 1977 against a peer-group mean of 1966 is 11 years newer.

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

Bridge inventory size and condition shares for Rockingham County and the 5 New Hampshire counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Hillsborough County	385	51.4%	39.7%	8.8%	1972
Merrimack County	326	45.1%	46.9%	8%	1966
Rockingham County (this page)	308	66.6%	26.9%	6.5%	1977
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

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 Rockingham 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 Rockingham County, both outside New Hampshire so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside NH (308 bridges here).

Surry County, NC · 308 bridges
Falls County, TX · 308 bridges
Kittitas County, WA · 308 bridges
Mississippi County, AR · 309 bridges

Similar average build year

Nearest mean year-built outside NH (1977 here).

San Diego County, CA · avg 1977 · 1,632 bridges
King County, WA · avg 1977 · 1,238 bridges
Riverside County, CA · avg 1977 · 1,117 bridges
Shelby County, TN · avg 1977 · 1,077 bridges

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

All 308 Good 205 Fair 83 Poor 20

All bridges (308)

Sort:

Rockingham County Bridge Snapshot

Condition distribution

Rockingham County's Poor-condition bridges carry 70,567 vehicle crossings a day

43.2% of Rockingham County's bridges have passed the 50-year mark

One structure carries 22.8% of the county's Poor-condition bridge traffic

How Rockingham 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

All bridges (308)

LANGFORD ROAD

DEPOT ROAD

NH101 EB

NH101 WB

I-95 SB

I-95

NH101 RAMP A-B

NH101

WINDSOR DRIVE

HAIGH ROAD

NH101 EB

NH101 WB

NEW BOSTON ROAD

NOTTINGHAM ROAD

EAST DERRY ROAD

MANTER MILL ROAD

HUNTER MILL WAY

SOUTH ROAD

WALNUT AVE

US 1 BYPASS

NH 1A

NH111

ASHLAND ROAD

GREEN ROAD

PATTEN HILL ROAD

DEERFIELD ROAD

I-93 SB

I-93 NB

TEAGUE DRIVE

SANDOWN ROAD

NH111

MILL STREET

GARDEN ROAD

NH 43 NH107

NH101 WB

CROSS STREET

US 1 BYPASS

US 1

I-93 NB

MAIN STREET

NH101 EB

NH152

WESTVILLE ROAD

NH111

SHERBURNE ROAD

OLD MANCHESTER RD

BOW LAKE ROAD

BEEDE ROAD

I-93 SB

I-93 NB

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