US Bridges

S-18-16 over Polk Swamp

Fair

Dorchester County, South Carolina · 4.6MI NW of ST George · Structure no. 000000000001873

Built
1952
73 years old, rebuilt 1995
Condition
Fair
inspected May 2023
Type
Slab
Concrete
Length
42 ft
3 main spans
Daily traffic
500
2023 count
Owner
State
State Highway Agency

About this bridge

S-18-16 over Polk Swamp is a concrete slab carrying S-18-16 over Polk Swamp in Dorchester County, South Carolina. It was built in 1952 and reconstructed in 1995, so it is 73 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 500 vehicles a day, roughly 5% of them trucks, projected to reach 730 by 2043. The structure is 42 ft (12.8 m) long and 26 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesS-18-16
CrossesPolk Swamp
Location4.6MI NW of ST George
RouteState Highway 16
CountyDorchester County
StateSouth Carolina
Coordinates33.21292, -80.6442
Functional classRural Major Collector

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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMay 2023
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 geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating35.1 US tons
Inventory rating21.1 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, precast panels
Main spans3
Design loadH 10
Structure length42 ft (12.8 m)
Longest span14 ft (4.3 m)
Deck width26 ft (7.8 m)
Roadway width21 ft (6.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic500 (2023)
Projected traffic730 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 proposedWidening with deck rehabilitation or replacement
Estimated improvement cost$153,000 (2024 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was S-18-16 over Polk Swamp built?

It was built in 1952, making it 73 years old in 2025. It was reconstructed in 1995.

What condition is S-18-16 over Polk 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 May 2023.

How much traffic does S-18-16 over Polk Swamp carry?

About 500 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is S-18-16 over Polk Swamp?

The structure is 42 ft (12.8 m) long with a longest span of 14 ft (4.3 m) and a deck 26 ft wide.

Who owns S-18-16 over Polk Swamp?

It is owned by the State Highway Agency.