US Bridges

County Road 21 over Slab Creek

Fair

Blount County, Alabama · 1 1/2 MI NW Highmound · Structure no. 011879

Built
1977
48 years old
Condition
Fair
inspected October 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
214 ft
3 main spans
Daily traffic
472
2023 count
Owner
County
County Highway Agency

About this bridge

County Road 21 over Slab Creek is a steel continuous stringer/multi-beam or girder carrying County Road 21 over Slab Creek in Blount County, Alabama. It was built in 1977, so it is 48 years old, younger 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 472 vehicles a day, roughly 2% of them trucks, projected to reach 702 by 2043. The structure is 214 ft (65.2 m) long and 27 ft wide. If it were closed, the detour would be 8.1 mi (13 km).

Location

Open in Google Maps
CarriesCounty Road 21
CrossesSlab Creek
Location1 1/2 MI NW Highmound
RouteCounty Highway 21
CountyBlount County
StateAlabama
Coordinates34.15863, -86.3937
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
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 inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating62.5 US tons
Inventory rating37.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3 (+1 approach)
Design loadH 20
Structure length214 ft (65.2 m)
Longest span60 ft (18.3 m)
Deck width27 ft (8.2 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic472 (2023)
Projected traffic702 by 2043
Trucks2%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed8.1 mi (13 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedWidening with deck rehabilitation or replacement
Estimated improvement cost$1.5 million (2025 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was County Road 21 over Slab Creek built?

It was built in 1977, making it 48 years old in 2025.

What condition is County Road 21 over Slab Creek 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 2023.

How much traffic does County Road 21 over Slab Creek carry?

About 472 vehicles per day (2023 count), of which roughly 2% are trucks.

How long is County Road 21 over Slab Creek?

The structure is 214 ft (65.2 m) long with a longest span of 60 ft (18.3 m) and a deck 27 ft wide.

Who owns County Road 21 over Slab Creek?

It is owned by the County Highway Agency.