County profile · official public datasets

Martin County, FL

129 public highway bridges tracked in the FHWA National Bridge Inventory: 72.9% rated Good, 26.4% Fair, 0.8% Poor.

129
Public bridges: 72.9%
Good condition: 0.8%
Poor condition

The verdict

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

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

Top 27%
lowest Poor share in state: 0.8%
Poor-condition share: 129
public highway bridges: 1983
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.

Martin County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Martin County ranks #18 of 67 Florida counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 0.8%). Martin County, Florida contains 129 public highway bridges. Roughly 72.9% are rated “Good,” 26.4% “Fair,” and 0.8% “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

129

Public highway bridges in Martin County

Good condition

72.9%

94 of 129 rated 7-9

Fair condition

26.4%

34 of 129 rated 5-6

Poor condition

0.8%

1 of 129 rated 4 or below

In-state Poor-share rank

#18 of 67

Among Florida counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 129 NBI-tracked bridges by lowest applicable component rating.

Good

72.9% (94)

Fair

26.4% (34)

Poor

0.8% (1)

Martin County's Poor-condition bridges carry 3,100 vehicle crossings a day

That is 0.1% of the county's reported daily bridge traffic on 0.8% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 3,100 crossings a day against 16,920 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 129 of 129 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

31.8% of Martin County's bridges have passed the 50-year mark

41 of the 129 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 72.9% 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 100% of the county's Poor-condition bridge traffic

SE COUNTY LINE RD over N Fork Loxahatchee River, built 1974, carries 3,100 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 1-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 3,100 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1950s

29
1960s

8
1970s

9
1980s

38
1990s

19
2000s

15
2010s

9
2020s

2

What this shows Construction peaked in the 1980s, when 38 of the county's bridges still in the inventory were built, which is 29.5% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year (1983) matches the Florida average (1983).

How Martin County compares with Florida's closest counties by inventory size

The 5 Florida counties nearest Martin County in number of bridges, with their condition splits. Its 0.8% Poor share is the 1st-lowest of these 6. Its average build year of 1983 against a peer-group mean of 1982 is in line with the group.

Showing the 5 closest of 66 Florida counties eligible for comparison.

Bridge inventory size and condition shares for Martin County and the 5 Florida counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
St. Johns County	141	61%	37.6%	1.4%	1988
Bay County	130	30.8%	59.2%	10%	1984
Martin County (this page)	129	72.9%	26.4%	0.8%	1983
Gadsden County	121	25.6%	61.2%	13.2%	1980
Indian River County	120	75%	23.3%	1.7%	1989
Alachua County	115	52.2%	47%	0.9%	1971

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 Martin 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 Martin County, both outside Florida so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside FL (129 bridges here).

Clay County, AL · 129 bridges
Cross County, AR · 129 bridges
Lake County, CA · 129 bridges
Lincoln County, CO · 129 bridges

Similar average build year

Nearest mean year-built outside FL (1983 here).

Dallas County, TX · avg 1983 · 3,230 bridges
Bexar County, TX · avg 1983 · 2,342 bridges
Sedgwick County, KS · avg 1983 · 1,333 bridges
Will County, IL · avg 1983 · 649 bridges

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

All 129 Good 94 Fair 34 Poor 1

All bridges (129)

Sort:

Martin County Bridge Snapshot

Condition distribution

Martin County's Poor-condition bridges carry 3,100 vehicle crossings a day

31.8% of Martin County's bridges have passed the 50-year mark

One structure carries 100% of the county's Poor-condition bridge traffic

How Martin County compares with Florida'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 (129)

US-1 (SR-5) NB

US-1 (SR-5) SB

SE ISLAND WAY ROAD

SR-710 Beeline Hwy

SR710 Warfield Blv

SR91 SB TPK 134.32

SR-732 (Jensen)

US-1 (SR-5) NB

SR91 N/S TPK 135.6

SR 707 (Dixie Hwy)

Jensen Bch. Cswy.

SR91 N/S TPK 126.5

CR-714 Indian St.

SR91 NS TPK 119.05

SR91 N/S TPK 138.1

CR708 SE BRIDGE RD

SR-76

SR 91 TPK 120.25

SR91 N/S TPK 123.9

SR91 N/S TPK 125.2

SR91 NS TPK 124.55

SR 91 TPK SB 130.8

US-1 (SR-5) SB

US-1 (SR-5) NB

SR91 N/S TPK 127.3

US-1 (SR-5)

EB Martin Downs Bl

I-95 (SR-9)

NB I-95 (SR-9)

SB I-95 (SR-9)

SR-714

WB Martin Downs Bl

SE HARBOR ISLAND

STAR ISLAND WAY

ISLAND RD.

LEIGHTON FARM AVE

EB SR - 714

DIXIE HIGHWAY

WB SR - 714

SR-91 TPK 134.1

SR 91 TPK 137.25

Indian Rvrsd Pk Rd

CR-726 CITRUS BLVD

CR-76A

CR-A1A(OCEAN BLVD)

SR-76 (Kanner Hwy)

US-1 (SR-5) SB

NB I-95 (SR-9)

SR-91 TPK NB130.75

SW 48th Avenue

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