County profile · official public datasets

Colleton County, SC

231 public highway bridges tracked in the FHWA National Bridge Inventory: 35.9% rated Good, 62.3% Fair, 1.7% Poor.

231
Public bridges: 35.9%
Good condition: 1.7%
Poor condition

The verdict

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

Colleton County pairs a top-10% lowest Poor-condition share among rated counties in the state with an older average build year than the state inventory.

Top 7%
lowest Poor share in state: 1.7%
Poor-condition share: 231
public highway bridges: 1971
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.

Colleton County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Colleton County ranks #3 of 46 South Carolina counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 1.7%). Colleton County, South Carolina contains 231 public highway bridges. Roughly 35.9% are rated “Good,” 62.3% “Fair,” and 1.7% “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

231

Public highway bridges in Colleton County

Good condition

35.9%

83 of 231 rated 7-9

Fair condition

62.3%

144 of 231 rated 5-6

Poor condition

1.7%

4 of 231 rated 4 or below

In-state Poor-share rank

#3 of 46

Among South Carolina counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 231 NBI-tracked bridges by lowest applicable component rating.

Good

35.9% (83)

Fair

62.3% (144)

Poor

1.7% (4)

Colleton County's Poor-condition bridges carry 24,000 vehicle crossings a day

That is 3.1% of the county's reported daily bridge traffic on 1.7% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 6,000 crossings a day against 2,014 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 231 of 231 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

66.7% of Colleton County's bridges have passed the 50-year mark

154 of the 231 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 35.9% 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 77.9% of the county's Poor-condition bridge traffic

US 17 over EDISTO RIVER, built 1953, carries 18,700 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 4-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 24,000 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

9
1930s

16
1940s

10
1950s

30
1960s

51
1970s

51
1980s

9
1990s

8
2000s

26
2010s

20
2020s

1

What this shows Construction peaked in the 1960s, when 51 of the county's bridges still in the inventory were built, which is 22.1% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1971, 6 years older than the South Carolina average of 1977.

How Colleton County compares with South Carolina's closest counties by inventory size

The 5 South Carolina counties nearest Colleton County in number of bridges, with their condition splits. Its 1.7% Poor share is the 1st-lowest of these 6. Its average build year of 1971 against a peer-group mean of 1976 is 5 years older.

Showing the 5 closest of 45 South Carolina counties eligible for comparison.

Bridge inventory size and condition shares for Colleton County and the 5 South Carolina counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Laurens County	259	32.8%	59.5%	7.7%	1974
Colleton County (this page)	231	35.9%	62.3%	1.7%	1971
Lexington County	229	48.5%	48.9%	2.6%	1981
Newberry County	218	31.7%	62.8%	5.5%	1974
Berkeley County	216	34.7%	63%	2.3%	1979
Oconee County	215	32.6%	53.5%	14%	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 Colleton 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 Colleton County, both outside South Carolina so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside SC (231 bridges here).

Saline County, AR · 231 bridges
Jones County, IA · 231 bridges
Clay County, KS · 231 bridges
Panola County, MS · 231 bridges

Similar average build year

Nearest mean year-built outside SC (1971 here).

Wayne County, MI · avg 1971 · 1,026 bridges
Baltimore County, MD · avg 1971 · 783 bridges
Washington County, PA · avg 1971 · 655 bridges
Linn County, OR · avg 1971 · 566 bridges

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

All 231 Good 83 Fair 144 Poor 4

Good-condition bridges (83)

Sort:

Colleton County Bridge Snapshot

Condition distribution

Colleton County's Poor-condition bridges carry 24,000 vehicle crossings a day

66.7% of Colleton County's bridges have passed the 50-year mark

One structure carries 77.9% of the county's Poor-condition bridge traffic

How Colleton County compares with South Carolina's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Good-condition bridges (83)

S-15-46/RED OAK RD

S-15-28

S-15-34

SC 63/SNIDERS HWY

SC 63/SNIDERS HWY

SC 63/ SNIDERS HWY

SC 63/SNIDER HWY

S-15-24

S-15-45/ROUND O RD

S-89/WOLFE CR RD

S-15-49/RUFFIN RD

S-15-28

S-15-21/SIDNEYS RD

S-15-66

S-15-166

US 21

S-24/MT CARMEL RD

S-48/BUCKHEAD RD

US 21

S-15-40

S-351/ASHTON RD

SC 63/SNIDERS HWY

S-15-40

S-15-86

SC 63

S-15-40

S-15-40

S-15-328

S-15-436

S-15-65

I-95 NB

S-66/COMBAHEE RD

US 17

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