US Bridges

Route I-81 over Rock Branch

Fair

Roanoke County, Virginia · 4.22-MONT Co; 2.61-RTE112 · Structure no. 000000000014904

Built
1964
61 years old
Condition
Fair
inspected April 2023
Type
Culvert
Concrete
Length
38 ft
3 main spans
Daily traffic
56,324
2022 count
Owner
State
State Highway Agency

About this bridge

Route I-81 over Rock Branch is a concrete culvert carrying Route I-81 over Rock Branch in Roanoke County, Virginia. It was built in 1964, so it is 61 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 56,324 vehicles a day, roughly 1% of them trucks, projected to reach 62,801 by 2045. The structure is 38 ft (11.6 m) long. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesRoute I-81
CrossesRock Branch
Location4.22-MONT Co; 2.61-RTE112
RouteInterstate 81
CountyRoanoke County
StateVirginia
Coordinates37.27452, -80.13967
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 inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating60 US tons
Inventory rating36 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans3
Design loadHS 20
Structure length38 ft (11.6 m)
Longest span10 ft (3 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic56,324 (2022)
Projected traffic62,801 by 2045
Trucks1%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 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$181.9 million (2017 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Route I-81 over Rock Branch built?

It was built in 1964, making it 61 years old in 2025.

What condition is Route I-81 over Rock Branch 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 April 2023.

How much traffic does Route I-81 over Rock Branch carry?

About 56,324 vehicles per day (2022 count), of which roughly 1% are trucks.

How long is Route I-81 over Rock Branch?

The structure is 38 ft (11.6 m) long with a longest span of 10 ft (3 m).

Who owns Route I-81 over Rock Branch?

It is owned by the State Highway Agency.