County profile · official public datasets

Charleston County, SC

336 public highway bridges tracked in the FHWA National Bridge Inventory: 37.8% rated Good, 59.8% Fair, 2.4% Poor.

336
Public bridges: 37.8%
Good condition: 2.4%
Poor condition

The verdict

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

Charleston County pairs a top-quartile lowest Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

Top 17%
lowest Poor share in state: 2.4%
Poor-condition share: 336
public highway bridges: 1988
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.

Charleston County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Charleston County ranks #8 of 46 South Carolina counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 2.4%). Charleston County, South Carolina contains 336 public highway bridges. Roughly 37.8% are rated “Good,” 59.8% “Fair,” and 2.4% “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

336

Public highway bridges in Charleston County

Good condition

37.8%

127 of 336 rated 7-9

Fair condition

59.8%

201 of 336 rated 5-6

Poor condition

2.4%

8 of 336 rated 4 or below

In-state Poor-share rank

#8 of 46

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

Condition distribution

Share of 336 NBI-tracked bridges by lowest applicable component rating.

Good

37.8% (127)

Fair

59.8% (201)

Poor

2.4% (8)

Charleston County's Poor-condition bridges carry 183,250 vehicle crossings a day

That is 3.2% of the county's reported daily bridge traffic on 2.4% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 22,906 crossings a day against 11,330 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 336 of 336 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

25.6% of Charleston County's bridges have passed the 50-year mark

86 of the 336 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 37.8% 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 47.9% of the county's Poor-condition bridge traffic

I-26 over RR CSXT, built 1963, carries 87,800 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 8-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 183,250 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

4
1930s

4
1940s

3
1950s

9
1960s

53
1970s

24
1980s

52
1990s

86
2000s

55
2010s

32
2020s

14

What this shows Construction peaked in the 1990s, when 86 of the county's bridges still in the inventory were built, which is 25.6% of those with a recorded year. That cohort is now 25 to 34 years old in the 2024 inventory. Its average build year is 1988, 11 years newer than the South Carolina average of 1977.

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

The 5 South Carolina counties nearest Charleston County in number of bridges, with their condition splits. Its 2.4% Poor share is the 1st-lowest of these 6. Its average build year of 1988 against a peer-group mean of 1977 is 11 years newer.

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

Bridge inventory size and condition shares for Charleston County and the 5 South Carolina counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Richland County	361	50.1%	46%	3.9%	1979
Charleston County (this page)	336	37.8%	59.8%	2.4%	1988
Pickens County	291	48.1%	42.6%	9.3%	1979
York County	288	42.7%	49.7%	7.6%	1984
Florence County	277	33.9%	63.5%	2.5%	1976
Orangeburg County	273	17.9%	76.6%	5.5%	1966

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 Charleston 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 Charleston County, both outside South Carolina so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside SC (336 bridges here).

Jefferson County, AR · 336 bridges
Kane County, IL · 336 bridges
Tuscarawas County, OH · 336 bridges
Warren County, OH · 336 bridges

Similar average build year

Nearest mean year-built outside SC (1988 here).

Travis County, TX · avg 1988 · 1,544 bridges
Grant County, OK · avg 1988 · 476 bridges
Loudoun County, VA · avg 1988 · 442 bridges
Licking County, OH · avg 1988 · 439 bridges

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

All 336 Good 127 Fair 201 Poor 8

Fair-condition bridges (201)

Sort:

Charleston County Bridge Snapshot

Condition distribution

Charleston County's Poor-condition bridges carry 183,250 vehicle crossings a day

25.6% of Charleston County's bridges have passed the 50-year mark

One structure carries 47.9% of the county's Poor-condition bridge traffic

How Charleston 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

Fair-condition bridges (201)

I-526 EB

I-526 WB

L-10-1255

RAMP ON SC 30 WB

RAMP ON SC 30 WB

SC 61

SC 642

S-10-195/EAGLE DR

SC 700/MAYBANK HWY

I-526 EBL

I-526 WB

RAMP ON I-26 EB

US 17 NB

L-2602/PARKERSLNDG

S-10-1028

I-26

S-10-894/AZALEA DR

RAMP ON I-526 EB

RAMP ON I-526 WB

RAMP OFF SC 30 EB

US 17 NB

S-10-54/RIVER RD

US 17 NB

US 17 SB

L-10-3976

L-2847/HRBRWATCHWY

RAMP ON I-526 EB

RAMP OFF I-526 EB

S-10-62

RAMP OFF US 17 SB

I-526 EB

SC 30

L-635/HYDE PARK RD

I-26

S-10-475

I-526 WBL

SC 703/PALM BLVD

S-10-62

I-26

S-10-60

S-10-894/AZALEA DR

S-10-58

I-26

I-26 EB

I-526 EB

I-526 WB

S-10-2418

US 17 SB

RAMP OFF I-526 WB

US 17 SB

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