US Bridges

S-15-66 over Calfpen Swamp

Good

Colleton County, South Carolina · 13 MI SW Waltb · Structure no. 000000000001946

Built
2010
15 years old
Condition
Good
inspected February 2025
Type
Slab
Prestressed Concrete
Length
130 ft
3 main spans
Daily traffic
100
2023 count
Owner
State
State Highway Agency

About this bridge

S-15-66 over Calfpen Swamp is a prestressed concrete slab carrying S-15-66 over Calfpen Swamp in Colleton County, South Carolina. It was built in 2010, so it is 15 years old, younger than the South Carolina average of 48 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 100 vehicles a day, roughly 11% of them trucks, projected to reach 128 by 2043. The structure is 130 ft (39.6 m) long and 36 ft wide. If it were closed, the detour would be 39.1 mi (63 km).

Location

Open in Google Maps
CarriesS-15-66
CrossesCalfpen Swamp
Location13 MI SW Waltb
RouteState Highway 66
CountyColleton County
StateSouth Carolina
Coordinates32.71423, -80.69586
Functional classRural Local

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionFebruary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation7: Better than present minimum criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating85.8 US tons
Inventory rating48.9 US tons

Structure

Structure typeSlab
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans3
Design loadHS 20
Structure length130 ft (39.6 m)
Longest span50 ft (15.2 m)
Deck width36 ft (11 m)
Roadway width33 ft (10 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic100 (2023)
Projected traffic128 by 2043
Trucks11%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed39.1 mi (63 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-15-66 over Calfpen Swamp built?

It was built in 2010, making it 15 years old in 2025.

What condition is S-15-66 over Calfpen Swamp in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in February 2025.

How much traffic does S-15-66 over Calfpen Swamp carry?

About 100 vehicles per day (2023 count), of which roughly 11% are trucks.

How long is S-15-66 over Calfpen Swamp?

The structure is 130 ft (39.6 m) long with a longest span of 50 ft (15.2 m) and a deck 36 ft wide.

Who owns S-15-66 over Calfpen Swamp?

It is owned by the State Highway Agency.