US Bridges

I-77 over US 21

Fair

York County, South Carolina · 3 MI N of Rock Hill · Structure no. 000000000006393

Built
1973
52 years old, rebuilt 2000
Condition
Fair
inspected March 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
201 ft
3 main spans
Daily traffic
92,100
2023 count
Owner
State
State Highway Agency

About this bridge

I-77 over US 21 is a steel stringer/multi-beam or girder carrying I-77 over US 21 in York County, South Carolina. It was built in 1973 and reconstructed in 2000, so it is 52 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 92,100 vehicles a day, roughly 14% of them trucks, projected to reach 128,940 by 2043. The structure is 201 ft (61.3 m) long and 139 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI-77
CrossesUS 21
Location3 MI N of Rock Hill
RouteInterstate 77
CountyYork County
StateSouth Carolina
Coordinates34.97361, -80.98694
Functional classUrban Principal Arterial - Interstate

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMarch 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating50.7 US tons
Inventory rating39.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length201 ft (61.3 m)
Longest span136 ft (41.5 m)
Deck width139 ft (42.5 m)
Roadway width134 ft (40.7 m)
Vertical clearance over deck100 ft (30.5 m)

Traffic and service

Average daily traffic92,100 (2023)
Projected traffic128,940 by 2043
Trucks14%
Lanes on structure8
Traffic directionTwo-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

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—
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-77 over US 21 built?

It was built in 1973, making it 52 years old in 2025. It was reconstructed in 2000.

What condition is I-77 over US 21 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 2024.

How much traffic does I-77 over US 21 carry?

About 92,100 vehicles per day (2023 count), of which roughly 14% are trucks.

How long is I-77 over US 21?

The structure is 201 ft (61.3 m) long with a longest span of 136 ft (41.5 m) and a deck 139 ft wide.

Who owns I-77 over US 21?

It is owned by the State Highway Agency.