US Bridges

I-77 Sbl over US21

Fair

Surry County, North Carolina · .25 MI.N.JCT.US21SBL · Structure no. 000000001710049

Built
1974
51 years old
Condition
Fair
inspected December 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
302 ft
3 main spans
Daily traffic
11,750
2020 count
Owner
State
State Highway Agency

About this bridge

I-77 Sbl over US21 is a steel stringer/multi-beam or girder carrying I-77 Sbl over US21 in Surry County, North Carolina. It was built in 1974, so it is 51 years old, older than the North Carolina average of 38.7 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 11,750 vehicles a day, roughly 23% of them trucks, projected to reach 23,500 by 2040. The structure is 302 ft (92 m) long and 42 ft wide.

Location

Open in Google Maps
CarriesI-77 Sbl
CrossesUS21
Location.25 MI.N.JCT.US21SBL
RouteInterstate 77
CountySurry County
StateNorth Carolina
Coordinates36.26443, -80.82559
Functional classRural 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.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionDecember 2023
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 geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating88 US tons
Inventory rating51.9 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length302 ft (92 m)
Longest span163 ft (49.6 m)
Deck width42 ft (12.8 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11,750 (2020)
Projected traffic23,500 by 2040
Trucks23%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed—
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 Sbl over US21 built?

It was built in 1974, making it 51 years old in 2025.

What condition is I-77 Sbl over US21 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 December 2023.

How much traffic does I-77 Sbl over US21 carry?

About 11,750 vehicles per day (2020 count), of which roughly 23% are trucks.

How long is I-77 Sbl over US21?

The structure is 302 ft (92 m) long with a longest span of 163 ft (49.6 m) and a deck 42 ft wide.

Who owns I-77 Sbl over US21?

It is owned by the State Highway Agency.