US Bridges

S-21-13 over Polk Swamp

FairPosted for load

Florence County, South Carolina · 7 MI E Florence · Structure no. 000000000005721

Built
1970
55 years old
Condition
Fair
inspected March 2023
Type
Slab
Concrete
Length
60 ft
4 main spans
Daily traffic
2,600
2023 count
Owner
State
State Highway Agency

About this bridge

S-21-13 over Polk Swamp is a concrete slab carrying S-21-13 over Polk Swamp in Florence County, South Carolina. It was built in 1970, so it is 55 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. Its operating status is: posted for load restriction.

It carries about 2,600 vehicles a day, roughly 7% of them trucks. The structure is 60 ft (18.3 m) long and 28 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesS-21-13
CrossesPolk Swamp
Location7 MI E Florence
RouteState Highway 13
CountyFlorence County
StateSouth Carolina
Coordinates34.14813, -79.64426
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 inspectionMarch 2023
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating30 US tons
Inventory rating17.9 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, precast panels
Main spans4
Design loadH 10
Structure length60 ft (18.3 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 traffic2,600 (2023)
Projected traffic—
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 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$93,000 (2024 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was S-21-13 over Polk Swamp built?

It was built in 1970, making it 55 years old in 2025.

What condition is S-21-13 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 March 2023.

How much traffic does S-21-13 over Polk Swamp carry?

About 2,600 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is S-21-13 over Polk Swamp?

The structure is 60 ft (18.3 m) long with a longest span of 15 ft (4.6 m) and a deck 28 ft wide.

Who owns S-21-13 over Polk Swamp?

It is owned by the State Highway Agency.