US Bridges

US21 over I77

Fair

Iredell County, North Carolina · 2.7 Mi. N. Jct. I40 · Structure no. 000000000970071

Built
1969
56 years old, rebuilt 2014
Condition
Fair
inspected June 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
342 ft
3 main spans
Daily traffic
11,000
2021 count
Owner
State
State Highway Agency

About this bridge

US21 over I77 is a steel continuous stringer/multi-beam or girder carrying US21 over I77 in Iredell County, North Carolina. It was built in 1969 and reconstructed in 2014, so it is 56 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 11,000 vehicles a day, roughly 8% of them trucks, projected to reach 22,000 by 2040. The structure is 342 ft (104.2 m) long and 70 ft wide. If it were closed, the detour would be 2.5 mi (4 km).

Location

Open in Google Maps
CarriesUS21
CrossesI77
Location2.7 Mi. N. Jct. I40
RouteU.S. Route 21
CountyIredell County
StateNorth Carolina
Coordinates35.84904, -80.859
Functional classRural Minor Arterial

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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionJune 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 rating57 US tons
Inventory rating34 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3 (+1 approach)
Design loadHS 20 + Mod
Structure length342 ft (104.2 m)
Longest span106 ft (32.3 m)
Deck width70 ft (21.4 m)
Roadway width68 ft (20.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11,000 (2021)
Projected traffic22,000 by 2040
Trucks8%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed2.5 mi (4 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—
NavigationNot applicable (no waterway)

Frequently asked questions

When was US21 over I77 built?

It was built in 1969, making it 56 years old in 2025. It was reconstructed in 2014.

What condition is US21 over I77 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 June 2024.

How much traffic does US21 over I77 carry?

About 11,000 vehicles per day (2021 count), of which roughly 8% are trucks.

How long is US21 over I77?

The structure is 342 ft (104.2 m) long with a longest span of 106 ft (32.3 m) and a deck 70 ft wide.

Who owns US21 over I77?

It is owned by the State Highway Agency.