County profile · official public datasets

Suffolk County, NY

369 public highway bridges tracked in the FHWA National Bridge Inventory: 27.1% rated Good, 71.5% Fair, 1.4% Poor.

369
Public bridges
27.1%
Good condition
1.4%
Poor condition

The verdict

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

Suffolk County posts a top-5% lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.

Top 3%
lowest Poor share in state
1.4%
Poor-condition share
369
public highway bridges
1968
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.

Suffolk County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Suffolk County ranks #2 of 62 New York counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 1.4%). Suffolk County, New York contains 369 public highway bridges. Roughly 27.1% are rated “Good,” 71.5% “Fair,” and 1.4% “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

369

Public highway bridges in Suffolk County

Good condition

27.1%

100 of 369 rated 7-9

Fair condition

71.5%

264 of 369 rated 5-6

Poor condition

1.4%

5 of 369 rated 4 or below

In-state Poor-share rank

#2 of 62

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

Condition distribution

Share of 369 NBI-tracked bridges by lowest applicable component rating.

Good
27.1% (100)
Fair
71.5% (264)
Poor
1.4% (5)

Suffolk County's Poor-condition bridges carry 54,548 vehicle crossings a day

That is 0.6% of the county's reported daily bridge traffic on 1.1% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 13,637 crossings a day against 25,957 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 366 of 369 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

71.3% of Suffolk County's bridges have passed the 50-year mark

263 of the 369 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 27.1% 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 71.8% of the county's Poor-condition bridge traffic

RTE 27 over NORTH RD, built 1959, carries 39,182 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 54,548 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Suffolk County's bridges were built

369 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1960s, when 96 of the county's bridges still in the inventory were built, which is 26% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1968) matches the New York average (1972).

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

How Suffolk County compares with New York's closest counties by inventory size

The 5 New York counties nearest Suffolk County in number of bridges, with their condition splits. Its 1.4% Poor share is the 1st-lowest of these 6. Its average build year of 1968 against a peer-group mean of 1974 is 6 years older.

Showing the 5 closest of 61 New York counties eligible for comparison.

Bridge inventory size and condition shares for Suffolk County and the 5 New York counties closest to it in inventory size
County Bridges Poor
Allegany County 402 6.2%
Ulster County 392 20.9%
Suffolk County (this page) 369 1.4%
Sullivan County 365 7.7%
Albany County 343 5.2%
Dutchess County 332 16.6%

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

Similar inventory size

Nearest county inventories outside NY (369 bridges here).

Similar average build year

Nearest mean year-built outside NY (1968 here).

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

All 369 Good 100 Fair 264 Poor 5

All bridges (369)

SPEONK-RIVERHD RD

Good

Over: 27 27 07051408 RTE 27

17 MI E RTS 112+27, Suffolk, NY

Built 1970 Load: 52.6 t ADT: 2,358

SWEZEY STREET

Good

Over: SWAN RIVER

0.3M S INTERS CO.RTS30&80, Suffolk, NY

Built 1988 Load: 54.1 t ADT: 3,549

RTE 27

Good

Over: COMMACK ROAD

.4 MI W JCT SH 27 & SH 11, Suffolk, NY

Built 1985 Load: 54.4 t ADT: 94,008

PECONIC BAY BLVD

Good

Over: BRUSHS CREEK

1.4m S of Rte 23, Suffolk, NY

Built 2003 Load: 56.2 t ADT: 2,121

Horse Block Road

Good

Over: Long Island RR LONG ISL

1.5 MI EAST OF MEDFORD, Suffolk, NY

Built 2020 Load: 56.2 t ADT: 19,439

CARLLS STRGT PATH

Good

Over: 495I495I07031069 RTE I4

1.2 MI E JCT RTS 231+495, Suffolk, NY

Built 2015 Load: 57.2 t ADT: 4,243

EMMETT DRIVE

Good

Over: Long Island RR

0.2 MI N Int Montauk Hwy, Suffolk, NY

Built 1999 Load: 60.3 t ADT: 1,293

BROOK AVE

Good

Over: 27 27 0705 1103 27 27 0

2.1 MI W JCT RTS 27+111, Suffolk, NY

Built 1970 Load: 62.2 t ADT: 10,910

RTE 114

Good

Over: SAG HARBOR COVE

RTE 114 AT SAG HARBOR, Suffolk, NY

Built 2000 Load: 67.1 t ADT: 5,956

MIDDLE ROAD

Good

Over: BROWNS CREEK

AT SAYVILLE, Suffolk, NY

Built 2014 Load: 70.8 t ADT: 5,389

LONG ISLAND MOTOR

Good

Over: 495I 495I 0703 1114 RTE

2.5 MI W JCT SH454 & I495, Suffolk, NY

Built 2011 Load: 71.7 t ADT: 21,748

RTE 110

Good

Over: RTE 908M

JCT SH 110 & SSP, Suffolk, NY

Built 1939 Load: 81.6 t ADT: 46,801

AWIXA AVENUE

Good

Over: AWIXA-PENATAQ.CNL

SOUTH OF BAYSHORE, Suffolk, NY

Built 1991 Load: 83.6 t ADT: 509

COUNTY ROAD 50

Good

Over: CARLLS RIVER

JCT S H 109 & S H 27, Suffolk, NY

Built 2002 Load: 99.9 t ADT: 11,884

RIVER AVENUE

Poor

Over: LONG ISLAND-MK BR

.5 MILE EAST OF EASTPORT, Suffolk, NY

Built 1907 Load: 0.0 t ADT: 337

PARK ROAD

Poor

Over: CONNETQUOT BROOK

CONNETQUOT RIVER ST PK, Suffolk, NY

Built 1900 Load: 9.8 t

FLOYD PKWY EXT

Poor

Over: NARROW BAY

SW OF MASTIC BEACH, Suffolk, NY

Built 1959 Load: 21.8 t ADT: 4,381

LINCOLN AVE

Poor

Over: 27 27 07051193 RTE 27

1.4 MI W OF SH 27 & SH 45, Suffolk, NY

Built 1996 Load: 24.6 t ADT: 10,648

RTE 27

Poor

Over: NORTH RD

3.3MI W OF TUCKAH, Suffolk, NY

Built 1959 Load: 33.6 t ADT: 39,182

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.