US Bridges

Al - 4 (us 78) over Cahaba River

Fair

Jefferson County, Alabama · Al - 4 Cahaba River · Structure no. 004770

Built
1955
70 years old
Condition
Fair
inspected June 2023
Type
Tee Beam
Concrete Continuous
Length
315 ft
3 main spans
Daily traffic
2,825
2023 count
Owner
State
State Highway Agency

About this bridge

Al - 4 (us 78) over Cahaba River is a concrete continuous tee beam carrying Al - 4 (us 78) over Cahaba River in Jefferson County, Alabama. It was built in 1955, so it is 70 years old, older than the Alabama average of 51.1 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 2,825 vehicles a day, roughly 5% of them trucks, projected to reach 3,643 by 2043. The structure is 315 ft (96 m) long and 33 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesAl - 4 (us 78)
CrossesCahaba River
LocationAl - 4 Cahaba River
RouteU.S. Route 78
CountyJefferson County
StateAlabama
Coordinates33.54597, -86.61336
Functional classRural Major 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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating41.6 US tons
Inventory rating24.9 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3 (+4 approach)
Design loadHS 20
Structure length315 ft (96 m)
Longest span70 ft (21.3 m)
Deck width33 ft (10.1 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,825 (2023)
Projected traffic3,643 by 2043
Trucks5%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 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 proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$2.6 million (2025 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Al - 4 (us 78) over Cahaba River built?

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

What condition is Al - 4 (us 78) over Cahaba River 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 June 2023.

How much traffic does Al - 4 (us 78) over Cahaba River carry?

About 2,825 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is Al - 4 (us 78) over Cahaba River?

The structure is 315 ft (96 m) long with a longest span of 70 ft (21.3 m) and a deck 33 ft wide.

Who owns Al - 4 (us 78) over Cahaba River?

It is owned by the State Highway Agency.