US Bridges

Nfa 1260 (sa 4731) over Thorngrove Road / I40

Fair

Knox County, Tennessee · .5 M NE of Thorn Grove · Structure no. 47I00400113

Built
1973
52 years old
Condition
Fair
inspected December 2024
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
372 ft
4 main spans
Daily traffic
835
2021 count
Owner
State
State Highway Agency

About this bridge

Nfa 1260 (sa 4731) over Thorngrove Road / I40 is a concrete continuous box beam or girders - multiple carrying Nfa 1260 (sa 4731) over Thorngrove Road / I40 in Knox County, Tennessee. It was built in 1973, so it is 52 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 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 835 vehicles a day, roughly 3% of them trucks, projected to reach 1,808 by 2041. The structure is 372 ft (113.4 m) long and 36 ft wide. If it were closed, the detour would be 9.9 mi (16 km).

Location

Open in Google Maps
CarriesNfa 1260 (sa 4731)
CrossesThorngrove Road / I40
Location.5 M NE of Thorn Grove
RouteCounty Highway 1260
CountyKnox County
StateTennessee
Coordinates35.99635, -83.7105
Functional classRural Minor Collector

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.
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 rating65.4 US tons
Inventory rating35.7 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length372 ft (113.4 m)
Longest span132 ft (40.2 m)
Deck width36 ft (11 m)
Roadway width34 ft (10.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic835 (2021)
Projected traffic1,808 by 2041
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
Detour if closed9.9 mi (16 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 1260 (sa 4731) over Thorngrove Road / I40 built?

It was built in 1973, making it 52 years old in 2025.

What condition is Nfa 1260 (sa 4731) over Thorngrove 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 1260 (sa 4731) over Thorngrove Road / I40 carry?

About 835 vehicles per day (2021 count), of which roughly 3% are trucks.

How long is Nfa 1260 (sa 4731) over Thorngrove Road / I40?

The structure is 372 ft (113.4 m) long with a longest span of 132 ft (40.2 m) and a deck 36 ft wide.

Who owns Nfa 1260 (sa 4731) over Thorngrove Road / I40?

It is owned by the State Highway Agency.