US Bridges

Nfa D670 over Union School Road / I40

Fair

Knox County, Tennessee · 1.4 M NW of SR9 · Structure no. 47I00400103

Built
1975
50 years old
Condition
Fair
inspected December 2024
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
250 ft
2 main spans
Daily traffic
300
2020 count
Owner
State
State Highway Agency

About this bridge

Nfa D670 over Union School Road / I40 is a concrete continuous box beam or girders - multiple carrying Nfa D670 over Union School Road / I40 in Knox County, Tennessee. It was built in 1975, so it is 50 years old, older than the Tennessee average of 47.4 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 300 vehicles a day, roughly 2% of them trucks, projected to reach 480 by 2041. The structure is 250 ft (76.2 m) long and 32 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesNfa D670
CrossesUnion School Road / I40
Location1.4 M NW of SR9
RouteCounty Highway 670
CountyKnox County
StateTennessee
Coordinates36.00415, -83.78815
Functional classUrban 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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionDecember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating48.2 US tons
Inventory rating37.1 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length250 ft (76.2 m)
Longest span125 ft (38.1 m)
Deck width32 ft (9.8 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic300 (2020)
Projected traffic480 by 2041
Trucks2%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
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 statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was Nfa D670 over Union School Road / I40 built?

It was built in 1975, making it 50 years old in 2025.

What condition is Nfa D670 over Union School Road / I40 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 December 2024.

How much traffic does Nfa D670 over Union School Road / I40 carry?

About 300 vehicles per day (2020 count), of which roughly 2% are trucks.

How long is Nfa D670 over Union School Road / I40?

The structure is 250 ft (76.2 m) long with a longest span of 125 ft (38.1 m) and a deck 32 ft wide.

Who owns Nfa D670 over Union School Road / I40?

It is owned by the State Highway Agency.