US Bridges

FAU 320 over Mackey Branch

Good

Hamilton County, Tennessee · 1.81 Mi. E of I-75 Jct. · Structure no. 33S43070005

Built
1992
33 years old
Condition
Good
inspected December 2024
Type
Culvert
Concrete Continuous
Length
58 ft
3 main spans
Daily traffic
32,653
2021 count
Owner
State
State Highway Agency

About this bridge

FAU 320 over Mackey Branch is a concrete continuous culvert carrying FAU 320 over Mackey Branch in Hamilton County, Tennessee. It was built in 1992, so it is 33 years old, younger than the Tennessee average of 47.4 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 32,653 vehicles a day, roughly 9% of them trucks, projected to reach 42,683 by 2042. The structure is 58 ft (17.7 m) long and 69 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesFAU 320
CrossesMackey Branch
Location1.81 Mi. E of I-75 Jct.
RouteState Highway 320
CountyHamilton County
StateTennessee
Coordinates35.00722, -85.15355
Functional classUrban Other Principal Arterial

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert7 GoodSome minor problems.
Last inspectionDecember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating78.3 US tons
Inventory rating35.7 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length58 ft (17.7 m)
Longest span18 ft (5.5 m)
Deck width69 ft (21 m)
Roadway width60 ft (18.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic32,653 (2021)
Projected traffic42,683 by 2042
Trucks9%
Lanes on structure5
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
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 statusHistorical significance not determinable at this time
Work proposedWidening of existing bridge without deck rehabilitation
Estimated improvement cost$319,000 (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was FAU 320 over Mackey Branch built?

It was built in 1992, making it 33 years old in 2025.

What condition is FAU 320 over Mackey Branch in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in December 2024.

How much traffic does FAU 320 over Mackey Branch carry?

About 32,653 vehicles per day (2021 count), of which roughly 9% are trucks.

How long is FAU 320 over Mackey Branch?

The structure is 58 ft (17.7 m) long with a longest span of 18 ft (5.5 m) and a deck 69 ft wide.

Who owns FAU 320 over Mackey Branch?

It is owned by the State Highway Agency.