County profile · official public datasets

Mercer County, NJ

414 public highway bridges tracked in the FHWA National Bridge Inventory: 40.3% rated Good, 50.5% Fair, 9.2% Poor.

414
Public bridges
40.3%
Good condition
9.2%
Poor condition

The verdict

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

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

17th
of 21 on Poor share
9.2%
Poor-condition share
414
public highway bridges
1975
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.

Mercer County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Mercer County ranks #17 of 21 New Jersey counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 9.2%). Mercer County, New Jersey contains 414 public highway bridges. Roughly 40.3% are rated “Good,” 50.5% “Fair,” and 9.2% “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

414

Public highway bridges in Mercer County

Good condition

40.3%

167 of 414 rated 7-9

Fair condition

50.5%

209 of 414 rated 5-6

Poor condition

9.2%

38 of 414 rated 4 or below

In-state Poor-share rank

#17 of 21

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

Condition distribution

Share of 414 NBI-tracked bridges by lowest applicable component rating.

Good
40.3% (167)
Fair
50.5% (209)
Poor
9.2% (38)

Mercer County's Poor-condition bridges carry 408,944 vehicle crossings a day

That is 4.8% of the county's reported daily bridge traffic on 9.2% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 10,762 crossings a day against 18,074 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 414 of 414 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

46.6% of Mercer County's bridges have passed the 50-year mark

192 of the 412 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 40.3% 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 10.3% of the county's Poor-condition bridge traffic

US ROUTE 1 over D&R CANAL, built 1973, carries 42,271 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 408,944 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Mercer County's bridges were built

412 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 2010s, when 89 of the county's bridges still in the inventory were built, which is 21.6% of those with a recorded year. That cohort is now 5 to 14 years old in the 2024 inventory. Its average build year is 1975, 9 years newer than the New Jersey average of 1966.

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

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

The 5 New Jersey counties nearest Mercer County in number of bridges, with their condition splits. Its 9.2% Poor share is the 4th-lowest of these 6. Its average build year of 1975 against a peer-group mean of 1964 is 11 years newer.

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

Bridge inventory size and condition shares for Mercer County and the 5 New Jersey counties closest to it in inventory size
County Bridges Poor
Mercer County (this page) 414 9.2%
Union County 409 4.2%
Somerset County 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 Mercer 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 Mercer County, both outside New Jersey so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside NJ (414 bridges here).

Similar average build year

Nearest mean year-built outside NJ (1975 here).

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

All 414 Good 167 Fair 209 Poor 38

All bridges (414)

I-295 SB

Fair

Over: ARENA DRIVE (CR 620)

AT I-295 EXIT 61, Mercer, NJ

Built 1984 Load: 81.6 t ADT: 35,160

CALHOUN ST CR 653

Fair

Over: Aband Belvid Del Flem RR

0.3 MILE S OF RT.31 JCT., Mercer, NJ

Built 1925 Load: 83.5 t ADT: 8,756

I-295 NORTHBOUND

Fair

Over: ARENA DRIVE (CR 620)

1.2MI N OF 195/295 INTCHG, Mercer, NJ

Built 1984 Load: 84.4 t ADT: 36,820

US1 & D&R CANAL

Fair

Over: SHABAKUNK CREEK

0.45 Mi. N. of CR 616, Mercer, NJ

Built 1973 Load: 89.8 t ADT: 33,922

HIGHTSTOWN ROAD

Fair

Over: BEAR BROOK

1.13 mile S of Rt 526, Mercer, NJ

Built 2013 Load: 94.6 t ADT: 21,925

US 130

Fair

Over: DOCTORS CREEK

0.5 MI S OF 130-524 JCT, Mercer, NJ

Built 1951 Load: 96.9 t ADT: 32,386

NJ 29

Fair

Over: MOORES CREEK

175 N of Pleasant Valley, Mercer, NJ

Built 1912 Load: 99.9 t ADT: 11,007

I-295

Fair

Over: EWING CREEK

0.81 MI N OF I-295 EXT 75, Mercer, NJ

Built 1960 Load: 99.9 t ADT: 91,741

US 206

Fair

Over: SHIPETAUKIN CREEK

0.1 MILE NORTH OF 569 JCT, Mercer, NJ

Built 1923 Load: 99.9 t ADT: 17,222

Ramp TSI

Good

Over: NJTPK (I-95)

At Interchange 7A, Mercer, NJ

Built 2012 Load: 17.5 t ADT: 4,405

ALEXANDER ROAD

Good

Over: DELAWARE & RARITAN CANAL

3/4 MI W OF RTS 1&571 JCT, Mercer, NJ

Built 1948 Load: 18.1 t ADT: 12,903

CR 526

Good

Over: BRIDEGROOM RUN

0.55 mile West of CR 535, Mercer, NJ

Built 1983 Load: 24.5 t ADT: 6,225

NJ 27

Good

Over: HARRYS BROOK

0.7 MI S. OF MILLSTONE RI, Mercer, NJ

Built 2004 Load: 26.2 t ADT: 13,725

CR533

Good

Over: POND RUN

0.7 mile South of I-295, Mercer, NJ

Built 1974 Load: 27.2 t ADT: 14,340

NJ RT 29 SB

Good

Over: WATSONS CREEK

0.39 MI N OF I-295 JCT, Mercer, NJ

Built 1995 Load: 27.2 t ADT: 37,700

EDGEBROOK ROAD

Good

Over: NJ TPK(I-95)

0.17 MI SOUTH of EXIT 7A, Mercer, NJ

Built 2011 Load: 27.2 t ADT: 1,286

N OLDEN AVE-CR 622

Good

Over: ASSUNPINK CREEK

0.14 MI N OF AMTRAK, Mercer, NJ

Built 1937 Load: 28.2 t ADT: 14,115

DISBROW HILL ROAD

Good

Over: ROCKY BROOK

0.68 MI EAST OF RT 571, Mercer, NJ

Built 1980 Load: 29.9 t ADT: 1,598

POND ROAD

Good

Over: MIRY RUN

0.5 MI WEST OF CR 526, Mercer, NJ

Built 1995 Load: 30.8 t ADT: 986

DUTCH NECK ROAD

Good

Over: S. BRANCH BIG BEAR BR.

0.7 MILES SE.CO.ROUTE 535, Mercer, NJ

Built 1975 Load: 30.8 t ADT: 1,460

NJ ROUTE 133 WB

Good

Over: US ROUTE 130

0.81 MI West OF RTE 571, Mercer, NJ

Built 1998 Load: 31.8 t ADT: 10,820

OLD MILL ROAD

Good

Over: STONY BROOK

1000 FT NW OF FDRL CTY RD, Mercer, NJ

Built 2012 Load: 32.4 t ADT: 1,609

ROUTE I-295

Good

Over: NJ 29NB NJ 175 D&RCanal

0.2 MI N OF DELAWARE RIV., Mercer, NJ

Built 2019 Load: 32.4 t ADT: 59,919

Windsor Road

Good

Over: NJTPK (I-95)

2.94 mi. north of Int. 7A, Mercer, NJ

Built 2012 Load: 32.4 t ADT: 1,682

Kuser Road

Good

Over: Pond Run

0.14 MI S OF CR 606, Mercer, NJ

Built 1988 Load: 32.7 t ADT: 9,045

Alexander Road

Good

Over: Tributary to Stony Brook

.22 M N of D&R Canal, Mercer, NJ

Built 2019 Load: 32.7 t ADT: 22,260

Lower Ferry Road

Good

Over: Golds Run

600 FEET EAST OF NJ 29, Mercer, NJ

Built 2022 Load: 32.7 t ADT: 8,995

COUNTY ROUTE 571

Good

Over: SCHENCK BROOK

0.5 mile of CR 539, Mercer, NJ

Built 1975 Load: 32.7 t ADT: 3,180

SOUTHARD STREET

Good

Over: US 1 and CONRAIL

0.23 MI N OF PERRY ST., Mercer, NJ

Built 2006 Load: 33.4 t ADT: 9,730

NJ RT 29 NB

Good

Over: WATSONS CREEK

0.41MI WEST OF 206 INT., Mercer, NJ

Built 1995 Load: 33.6 t ADT: 37,858

I-295 RAMPS G & C

Good

Over: D&R CANAL&SHIPETAUKIN CK

AT RT 1 INTERSECTION, Mercer, NJ

Built 1974 Load: 33.7 t ADT: 13,227

Ramp SIT

Good

Over: NJTPK (I-95)

At Interchange 7A, Mercer, NJ

Built 2012 Load: 34.0 t ADT: 3,931

FEDERAL CITY ROAD

Good

Over: S. BRANCH OF STONY BRK

0.2 MI W OF OLD MILL ROAD, Mercer, NJ

Built 2007 Load: 34.5 t ADT: 1,479

US 1

Good

Over: MILLSTONE RIVER

5.2 MI NORTH OF I-295, Mercer, NJ

Built 2010 Load: 34.5 t ADT: 93,321

I-195 EB

Good

Over: NJTP & RAMP TP SB TO 195

1.94 MI E of US 130 JCT, Mercer, NJ

Built 2014 Load: 35.0 t ADT: 32,774

Int. 8 Rmp NT & TS

Good

Over: NJTPK

At Interchange 8, Mercer, NJ

Built 2013 Load: 35.0 t ADT: 10,407

Ramp TN

Good

Over: I-195

At Interchange 7A, Mercer, NJ

Built 2012 Load: 35.3 t ADT: 4,406

Ewingville Road

Good

Over: Shabakunk Creek

0.35M South of NJ RT.31, Mercer, NJ

Built 2000 Load: 35.4 t ADT: 13,882

BRANDON ROAD WEST

Good

Over: SHABAKUNK CREEK

0.64 Mi E. OF RT. 31, Mercer, NJ

Built 1994 Load: 35.4 t ADT: 468

CR 518 (E. Broad)

Good

Over: BEDENS BROOK

0.5 MI EAST OF CO. 569, Mercer, NJ

Built 2019 Load: 36.0 t ADT: 10,642

CR 518

Good

Over: BRANCH OF STONY BROOK

1.1 mile East of Rt. 31, Mercer, NJ

Built 1991 Load: 36.3 t ADT: 5,325

MEADOW ROAD

Good

Over: US ROUTE 1

2.7MI NORTH OF I-295 JCT, Mercer, NJ

Built 2003 Load: 36.3 t ADT: 17,228

I-295 NB

Good

Over: WATSONS CRK NJ TRNST D&R

0.54 MI S I195 & I295 JCT, Mercer, NJ

Built 1994 Load: 36.3 t ADT: 48,858

Ramp SANI

Good

Over: NJTPK (I-95)

Service Area 6N, Mercer, NJ

Built 2013 Load: 36.6 t ADT: 5,670

Ramp TNI

Good

Over: NJTPK SNO

At Interchange 7A, Mercer, NJ

Built 2012 Load: 36.6 t ADT: 4,405

I-195 WB

Good

Over: I-295 RAMP H

0.14 MI EAST OF I-295, Mercer, NJ

Built 1994 Load: 37.2 t ADT: 38,847

Ramp TSI

Good

Over: NSO Roadway

At Interchange 8, Mercer, NJ

Built 2014 Load: 37.6 t ADT: 1,975

Yardville-ATown

Good

Over: NJTPK (I-95)

1.9 MI SOUTH OF INT 7A, Mercer, NJ

Built 2013 Load: 37.9 t ADT: 5,358

I-295

Good

Over: POND RUN

4.66 MI SOUTH OF US RT 1, Mercer, NJ

Built 1975 Load: 38.1 t ADT: 74,849

CARLTON AVENUE

Good

Over: WEST BR. SHABAKUNK CRK

0.6 mile West of Rt. 31, Mercer, NJ

Built 2013 Load: 38.6 t ADT: 1,000

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

Related

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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.