US Bridges

I-81 Nbl over Duncan Run

Fair

Frederick County, Virginia · 2.23 to 672 - 0.31 to 669 · Structure no. 000000000008143

Built
1965
60 years old
Condition
Fair
inspected March 2025
Type
Culvert
Concrete
Length
38 ft
4 main spans
Daily traffic
26,774
2022 count
Owner
State
State Highway Agency

About this bridge

I-81 Nbl over Duncan Run is a concrete culvert carrying I-81 Nbl over Duncan Run in Frederick County, Virginia. It was built in 1965, so it is 60 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 26,774 vehicles a day, roughly 1% of them trucks, projected to reach 32,564 by 2045. The structure is 38 ft (11.6 m) long. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI-81 Nbl
CrossesDuncan Run
Location2.23 to 672 - 0.31 to 669
RouteInterstate 81
CountyFrederick County
StateVirginia
Coordinates39.28669, -78.08648
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 protection8 Very GoodNo problems noted.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMarch 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating83 US tons
Inventory rating49.1 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans4
Design loadHS 20
Structure length38 ft (11.6 m)
Longest span9 ft (2.7 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic26,774 (2022)
Projected traffic32,564 by 2045
Trucks1%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
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—
NavigationNo navigation control on waterway

Frequently asked questions

When was I-81 Nbl over Duncan Run built?

It was built in 1965, making it 60 years old in 2025.

What condition is I-81 Nbl over Duncan Run 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 2025.

How much traffic does I-81 Nbl over Duncan Run carry?

About 26,774 vehicles per day (2022 count), of which roughly 1% are trucks.

How long is I-81 Nbl over Duncan Run?

The structure is 38 ft (11.6 m) long with a longest span of 9 ft (2.7 m).

Who owns I-81 Nbl over Duncan Run?

It is owned by the State Highway Agency.