US Bridges

LA0408 over Blackwater Bayou

Good

East Baton Rouge Parish, Louisiana · 3.5 M E of LA 67&LA 408 · Structure no. 611702550203932

Built
1984
41 years old
Condition
Good
inspected April 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
150 ft
3 main spans
Daily traffic
19,515
2021 count
Owner
State
State Highway Agency

About this bridge

LA0408 over Blackwater Bayou is a prestressed concrete continuous stringer/multi-beam or girder carrying LA0408 over Blackwater Bayou in East Baton Rouge Parish, Louisiana. It was built in 1984, so it is 41 years old, younger than the Louisiana average of 43 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 19,515 vehicles a day, roughly 9% of them trucks, projected to reach 21,466 by 2041. The structure is 150 ft (45.7 m) long and 47 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

CarriesLA0408
CrossesBlackwater Bayou
Location3.5 M E of LA 67&LA 408
RouteState Highway 408
Coordinates30.53554, -91.08159
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionApril 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than 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 alignment8: Equal to present desirable criteria
Operating rating75.9 US tons
Inventory rating45 US tons

Structure

MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length150 ft (45.7 m)
Longest span50 ft (15.2 m)
Deck width47 ft (14.2 m)
Roadway width34 ft (10.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic19,515 (2021)
Projected traffic21,466 by 2041
Trucks9%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was LA0408 over Blackwater Bayou built?

It was built in 1984, making it 41 years old in 2025.

What condition is LA0408 over Blackwater Bayou 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 April 2024.

How much traffic does LA0408 over Blackwater Bayou carry?

About 19,515 vehicles per day (2021 count), of which roughly 9% are trucks.

How long is LA0408 over Blackwater Bayou?

The structure is 150 ft (45.7 m) long with a longest span of 50 ft (15.2 m) and a deck 47 ft wide.

Who owns LA0408 over Blackwater Bayou?

It is owned by the State Highway Agency.