US Bridges

Fdr 521 over Four Mile Branch

Fair

Grant Parish, Louisiana · Logmi 0.19 FR 532 to · Structure no. 080604000002417

Built
1955
70 years old
Condition
Fair
inspected October 2024
Type
Channel Beam
Prestressed Concrete
Length
40 ft
2 main spans
Daily traffic
26
1979 count
Owner
Federal
U.S. Forest Service

About this bridge

Fdr 521 over Four Mile Branch is a prestressed concrete channel beam carrying Fdr 521 over Four Mile Branch in Grant Parish, Louisiana. It was built in 1955, so it is 70 years old, older than the Louisiana average of 43 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 26 vehicles a day, projected to reach 39 by 2045. The structure is 40 ft (12.2 m) long and 14 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesFdr 521
CrossesFour Mile Branch
LocationLogmi 0.19 FR 532 to
RouteFederal Lands Road 521.3
CountyGrant Parish
StateLouisiana
Coordinates31.78498, -92.53839
Functional classRural Local

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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating24.7 US tons
Inventory rating15.3 US tons

Structure

Structure typeChannel Beam
MaterialPrestressed Concrete
DeckOther
Main spans2
Design loadHS 20
Structure length40 ft (12.2 m)
Longest span20 ft (6.1 m)
Deck width14 ft (4.2 m)
Roadway width12 ft (3.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic26 (1979)
Projected traffic39 by 2045
Trucks—
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerU.S. Forest Service
Maintained byU.S. Forest Service
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Fdr 521 over Four Mile Branch built?

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

What condition is Fdr 521 over Four Mile Branch 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 2024.

How much traffic does Fdr 521 over Four Mile Branch carry?

About 26 vehicles per day (1979 count).

How long is Fdr 521 over Four Mile Branch?

The structure is 40 ft (12.2 m) long with a longest span of 20 ft (6.1 m) and a deck 14 ft wide.

Who owns Fdr 521 over Four Mile Branch?

It is owned by the U.S. Forest Service.