County profile · official public datasets

Somerset County, NJ

397 public highway bridges tracked in the FHWA National Bridge Inventory: 33% rated Good, 57.4% Fair, 9.6% Poor.

397
Public bridges
33%
Good condition
9.6%
Poor condition

The verdict

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

Somerset County posts a higher-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.

19th
of 21 on Poor share
9.6%
Poor-condition share
397
public highway bridges
1970
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.

Somerset County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Somerset County ranks #19 of 21 New Jersey counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 9.6%). Somerset County, New Jersey contains 397 public highway bridges. Roughly 33% are rated “Good,” 57.4% “Fair,” and 9.6% “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

397

Public highway bridges in Somerset County

Good condition

33%

131 of 397 rated 7-9

Fair condition

57.4%

228 of 397 rated 5-6

Poor condition

9.6%

38 of 397 rated 4 or below

In-state Poor-share rank

#19 of 21

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

Condition distribution

Share of 397 NBI-tracked bridges by lowest applicable component rating.

Good
33% (131)
Fair
57.4% (228)
Poor
9.6% (38)

Somerset County's Poor-condition bridges carry 639,320 vehicle crossings a day

That is 10% of the county's reported daily bridge traffic on 9.6% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 16,824 crossings a day against 9,020 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 397 of 397 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

54.2% of Somerset County's bridges have passed the 50-year mark

215 of the 397 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 33% 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 9.2% of the county's Poor-condition bridge traffic

I-78 EASTBOUND over I-78 RAMP "A", built 1963, carries 58,865 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 38-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 639,320 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Somerset County's bridges were built

397 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1960s, when 108 of the county's bridges still in the inventory were built, which is 27.2% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1970) matches the New Jersey average (1966).

Source FHWA National Bridge Inventory (year built) As of 2024 NBI release

How Somerset County compares with New Jersey's closest counties by inventory size

The 5 New Jersey counties nearest Somerset County in number of bridges, with their condition splits. Its 9.6% Poor share is the 5th-lowest of these 6. Its average build year of 1970 against a peer-group mean of 1965 is 5 years newer.

Showing the 5 closest of 20 New Jersey counties eligible for comparison.

Bridge inventory size and condition shares for Somerset County and the 5 New Jersey counties closest to it in inventory size
County Bridges Poor
Mercer County 414 9.2%
Union County 409 4.2%
Somerset County (this page) 397 9.6%
Hunterdon County 373 7.5%
Burlington County 356 10.1%
Passaic County 333 3.3%

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

Similar inventory size

Nearest county inventories outside NJ (397 bridges here).

Similar average build year

Nearest mean year-built outside NJ (1970 here).

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

All 397 Good 131 Fair 228 Poor 38

Fair-condition bridges (228)

HILLCREST RD RT531

Fair

Over: PASSAIC RIVER

1.50 mi N of I-78, Somerset, NJ

Built 1998 Load: 75.3 t ADT: 10,560

GROVE STREET

Fair

Over: STONY BROOK

0.08 MI SO US 22, Somerset, NJ

Built 2005 Load: 75.3 t ADT: 1,144

CR 652 (ALLEN RD)

Fair

Over: DEAD RIVER

.41 MI W OF CNTY RT 525, Somerset, NJ

Built 2005 Load: 76.2 t ADT: 6,902

NJ 28

Fair

Over: GREEN BROOK

1.65 MI EAST OF I-287 JCT, Somerset, NJ

Built 1961 Load: 77.8 t ADT: 20,812

BURNT MILLS ROAD

Fair

Over: N BRANCH RARITAN RIVER

0.30 MI E CR641, Somerset, NJ

Built 1940 Load: 78.9 t ADT: 4,029

STIRLING ROAD

Fair

Over: STONY BROOK

0.88 MI S OF I-78, Somerset, NJ

Built 2002 Load: 78.9 t ADT: 9,945

BELLMD-GRIGTWN-630

Fair

Over: TRIB TO PIKE RUN

0.60 mi east of US 206, Somerset, NJ

Built 1991 Load: 83.5 t ADT: 4,558

US 202

Fair

Over: HOLLAND BROOK

5.07 MI S OF 202-206 CIRC, Somerset, NJ

Built 1933 Load: 84.4 t ADT: 42,436

I-287 RAMP "A"

Fair

Over: I-287 RAMP "B"

AT I-287 EXIT 10, Somerset, NJ

Built 1960 Load: 84.9 t ADT: 16,455

WERTSVILLE ROAD

Fair

Over: TRIB OF NESHANIC RIVER

0.6 MI WEST MONTGOMERY RD, Somerset, NJ

Built 1997 Load: 85.3 t ADT: 1,757

I-287NB RAMP A & E

Fair

Over: CHAMBERS BROOK

0.34 MI South of I-78, Somerset, NJ

Built 1963 Load: 87.5 t ADT: 75,187

OPOSSUM ROAD

Fair

Over: BEDENS BROOK

1 MI SOUTH OF US 206, Somerset, NJ

Built 1822 Load: 88.9 t ADT: 1,863

CANAL ROAD

Fair

Over: SIX MILE RUN

0.2 MI SO BLACKWELLS MILL, Somerset, NJ

Built 1834 Load: 89.8 t ADT: 3,641

WILLOW AVE

Fair

Over: TRIB TO D&R CANAL

0.3 MI E NEW BRUNSWICK R, Somerset, NJ

Built 1979 Load: 89.8 t ADT: 607

STILES ROAD

Fair

Over: STONY BROOK

.1 MI N OF STIRLING RD, Somerset, NJ

Built 1998 Load: 89.8 t ADT: 405

US 22 EB

Fair

Over: N BR OF RARITAN RIVER

.75 MI WEST OF NJ 28, Somerset, NJ

Built 1942 Load: 99.9 t ADT: 17,200

US 22 WB

Fair

Over: N BR. RARITAN RIVER

0.76 MI W OF NJ 28, Somerset, NJ

Built 1942 Load: 99.9 t ADT: 17,240

ROUTE US 22

Fair

Over: BR OF PETERS BROOK

0.5 MI W OF 202 & 206 JCT, Somerset, NJ

Built 1949 Load: 99.9 t ADT: 43,534

RT US 22

Fair

Over: PETERS BROOK

.2 MI WEST OF 202&206 JCT, Somerset, NJ

Built 1949 Load: 99.9 t ADT: 35,286

US 202

Fair

Over: NO.BR.RARITAN RIVER

1.35MI N OF CR 637, Somerset, NJ

Built 1934 Load: 99.9 t ADT: 61,761

US 202 & 206

Fair

Over: PETERS BROOK

0.17 MI SOUTH OF US22, Somerset, NJ

Built 1929 Load: 99.9 t ADT: 99,960

I-287

Fair

Over: SKY BROOK

2.46 mi S of Exit 13, Somerset, NJ

Built 1959 Load: 99.9 t ADT: 122,240

I-287 NB

Fair

Over: ROSS BROOK

1.8MI NORTH OF US 22 JCT, Somerset, NJ

Built 1963 Load: 99.9 t ADT: 48,732

I-78

Fair

Over: Corys Brook

1.1 MI E OF I-78 EXIT 36, Somerset, NJ

Built 1965 Load: 99.9 t ADT: 103,563

RARITAN RIVER

Fair

Over: LYMAN STREET/RIVER ROAD

0.1 Mi S. of CR 567, Somerset, NJ

Built 2005 Load: 99.9 t ADT: 7,795

AMWELL RD (CR 514)

Fair

Over: ROYCE BROOK

1.0 MI EAST OF US206, Somerset, NJ

Built 1986 Load: 99.9 t ADT: 19,252

GROVE ST

Fair

Over: PETERS BROOK

0.38 mi N of NJ 28, Somerset, NJ

Built 1996 Load: 99.9 t ADT: 11,141

CORIELL DRIVE

Fair

Over: CHAMBERS BROOK

SOUTH OF N.SHORE DRIVE, Somerset, NJ

Built 1930 Load: 99.9 t ADT: 609

Read our methodology - how this data is sourced, computed, and verified.

Related

Browse all → | Rankings →
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.