US Bridges

Unison Road over Dog Branch

Fair

Loudoun County, Virginia · 00.85FR700/ 00.70 626 · Structure no. 000000000011204

Built
1955
70 years old, rebuilt 1998
Condition
Fair
inspected October 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
55 ft
1 main span
Daily traffic
51
2014 count
Owner
State
State Highway Agency

About this bridge

Unison Road over Dog Branch is a steel stringer/multi-beam or girder carrying Unison Road over Dog Branch in Loudoun County, Virginia. It was built in 1955 and reconstructed in 1998, so it is 70 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 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 51 vehicles a day, projected to reach 59 by 2042. The structure is 55 ft (16.8 m) long and 22 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

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CarriesUnison Road
CrossesDog Branch
Location00.85FR700/ 00.70 626
RouteCounty Highway 630
CountyLoudoun County
StateVirginia
Coordinates39.04309, -77.78049
Functional classRural Local

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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; action required to protect exposed foundations
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating58 US tons
Inventory rating44.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckWood or timber
Main spans1
Design loadHS 20
Structure length55 ft (16.8 m)
Longest span55 ft (16.8 m)
Deck width22 ft (6.6 m)
Roadway width20 ft (6.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic51 (2014)
Projected traffic59 by 2042
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$370 million
NavigationNo navigation control on waterway

Frequently asked questions

When was Unison Road over Dog Branch built?

It was built in 1955, making it 70 years old in 2025. It was reconstructed in 1998.

What condition is Unison Road over Dog 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 October 2024.

How much traffic does Unison Road over Dog Branch carry?

About 51 vehicles per day (2014 count).

How long is Unison Road over Dog Branch?

The structure is 55 ft (16.8 m) long with a longest span of 55 ft (16.8 m) and a deck 22 ft wide.

Who owns Unison Road over Dog Branch?

It is owned by the State Highway Agency.