US Bridges

S-21-107 over Alligator Branch

Good

Florence County, South Carolina · 3 MI SW Florence · Structure no. 000000000010344

Built
2023
2 years old
Condition
Good
inspected April 2023
Type
Slab
Concrete Continuous
Length
100 ft
3 main spans
Daily traffic
10,200
2023 count
Owner
State
State Highway Agency

About this bridge

S-21-107 over Alligator Branch is a concrete continuous slab carrying S-21-107 over Alligator Branch in Florence County, South Carolina. It was built in 2023, so it is 2 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 9 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 10,200 vehicles a day, roughly 4% of them trucks, projected to reach 6,834 by 2043. The structure is 100 ft (30.5 m) long and 83 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesS-21-107
CrossesAlligator Branch
Location3 MI SW Florence
RouteState Highway 107
CountyFlorence County
StateSouth Carolina
Coordinates34.13654, -79.78213
Functional classUrban Minor Arterial

Condition and inspection

Good

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

ComponentRatingMeaning
Deck9 ExcellentNo problems noted.
Superstructure9 ExcellentNo problems noted.
Substructure9 ExcellentNo problems noted.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation9: Superior to present desirable criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating60 US tons
Inventory rating46.1 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHL 93
Structure length100 ft (30.5 m)
Longest span40 ft (12.2 m)
Deck width83 ft (25.3 m)
Roadway width70 ft (21.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic10,200 (2023)
Projected traffic6,834 by 2043
Trucks4%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed3.1 mi (5 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-21-107 over Alligator Branch built?

It was built in 2023, making it 2 years old in 2025.

What condition is S-21-107 over Alligator Branch 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 April 2023.

How much traffic does S-21-107 over Alligator Branch carry?

About 10,200 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is S-21-107 over Alligator Branch?

The structure is 100 ft (30.5 m) long with a longest span of 40 ft (12.2 m) and a deck 83 ft wide.

Who owns S-21-107 over Alligator Branch?

It is owned by the State Highway Agency.