US Bridges

US 521 over Stony Run

Fair

Williamsburg County, South Carolina · 6.0 MI S of Kingstree · Structure no. 000000000000586

Built
1931
94 years old, rebuilt 1965
Condition
Fair
inspected November 2024
Type
Culvert
Concrete Continuous
Length
25 ft
2 main spans
Daily traffic
3,100
2023 count
Owner
State
State Highway Agency

About this bridge

US 521 over Stony Run is a concrete continuous culvert carrying US 521 over Stony Run in Williamsburg County, South Carolina. It was built in 1931 and reconstructed in 1965, so it is 94 years old, older than the South Carolina average of 48 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 3,100 vehicles a day, roughly 16% of them trucks, projected to reach 5,394 by 2043. The structure is 25 ft (7.6 m) long and 53 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

CarriesUS 521
CrossesStony Run
Location6.0 MI S of Kingstree
RouteU.S. Route 521
Coordinates33.57911, -79.81641
Functional classRural Principal Arterial - Other

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Channel and channel protection7 GoodSome minor problems.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating46.4 US tons
Inventory rating27.4 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckNot applicable
Main spans2
Design loadH 15
Structure length25 ft (7.6 m)
Longest span12 ft (3.7 m)
Deck width53 ft (16.3 m)
Roadway width27 ft (8.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,100 (2023)
Projected traffic5,394 by 2043
Trucks16%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was US 521 over Stony Run built?

It was built in 1931, making it 94 years old in 2025. It was reconstructed in 1965.

What condition is US 521 over Stony Run in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in November 2024.

How much traffic does US 521 over Stony Run carry?

About 3,100 vehicles per day (2023 count), of which roughly 16% are trucks.

How long is US 521 over Stony Run?

The structure is 25 ft (7.6 m) long with a longest span of 12 ft (3.7 m) and a deck 53 ft wide.

Who owns US 521 over Stony Run?

It is owned by the State Highway Agency.