US Bridges

S-16-990 over Lake Swamp

Fair

Darlington County, South Carolina · 5.0 MI NE Lamar · Structure no. 000000000006651

Built
1975
50 years old, rebuilt 2002
Condition
Fair
inspected February 2025
Type
Slab
Concrete
Length
75 ft
5 main spans
Daily traffic
175
2023 count
Owner
State
State Highway Agency

About this bridge

S-16-990 over Lake Swamp is a concrete slab carrying S-16-990 over Lake Swamp in Darlington County, South Carolina. It was built in 1975 and reconstructed in 2002, so it is 50 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 5 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 175 vehicles a day, roughly 5% of them trucks, projected to reach 224 by 2043. The structure is 75 ft (22.9 m) long and 28 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesS-16-990
CrossesLake Swamp
Location5.0 MI NE Lamar
RouteState Highway 990
CountyDarlington County
StateSouth Carolina
Coordinates34.18458, -79.98866
Functional classRural Local

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionFebruary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating31.1 US tons
Inventory rating18.5 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, precast panels
Main spans5
Design loadH 10
Structure length75 ft (22.9 m)
Longest span15 ft (4.6 m)
Deck width28 ft (8.4 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic175 (2023)
Projected traffic224 by 2043
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemNo

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 S-16-990 over Lake Swamp built?

It was built in 1975, making it 50 years old in 2025. It was reconstructed in 2002.

What condition is S-16-990 over Lake Swamp 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 February 2025.

How much traffic does S-16-990 over Lake Swamp carry?

About 175 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is S-16-990 over Lake Swamp?

The structure is 75 ft (22.9 m) long with a longest span of 15 ft (4.6 m) and a deck 28 ft wide.

Who owns S-16-990 over Lake Swamp?

It is owned by the State Highway Agency.