US Bridges

Interstate 81 over Nbl&sbl over Stream

Fair

Smyth County, Virginia · 3.4 to R107;.46 to R11 · Structure no. 000000000017489

Built
1963
62 years old
Condition
Fair
inspected February 2025
Type
Culvert
Concrete
Length
23 ft
3 main spans
Daily traffic
31,442
2022 count
Owner
State
State Highway Agency

About this bridge

Interstate 81 over Nbl&sbl over Stream is a concrete culvert carrying Interstate 81 over Nbl&sbl over Stream in Smyth County, Virginia. It was built in 1963, so it is 62 years old, older than the Virginia average of 50.7 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 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 31,442 vehicles a day, roughly 1% of them trucks, projected to reach 35,058 by 2045. The structure is 23 ft (7 m) long. If it were closed, the detour would be 3.7 mi (6 km).

Location

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CarriesInterstate 81
CrossesNbl&sbl over Stream
Location3.4 to R107;.46 to R11
RouteInterstate 81
CountySmyth County
StateVirginia
Coordinates36.80625, -81.62624
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
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionFebruary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating49.1 US tons
Inventory rating36 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans3
Design loadHS 20
Structure length23 ft (7 m)
Longest span8 ft (2.4 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic31,442 (2022)
Projected traffic35,058 by 2045
Trucks1%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$65 million
NavigationNo navigation control on waterway

Frequently asked questions

When was Interstate 81 over Nbl&sbl over Stream built?

It was built in 1963, making it 62 years old in 2025.

What condition is Interstate 81 over Nbl&sbl over Stream 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 February 2025.

How much traffic does Interstate 81 over Nbl&sbl over Stream carry?

About 31,442 vehicles per day (2022 count), of which roughly 1% are trucks.

How long is Interstate 81 over Nbl&sbl over Stream?

The structure is 23 ft (7 m) long with a longest span of 8 ft (2.4 m).

Who owns Interstate 81 over Nbl&sbl over Stream?

It is owned by the State Highway Agency.