US Bridges

Rocky Branch RD over Bayou Darbonne

PoorPosted for load

Union Parish, Louisiana · 1.1 Mi. W. Int. 489 · Structure no. 055632407921411

Built
1974
51 years old
Condition
Poor
inspected May 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
723 ft
31 main spans
Daily traffic
117
2019 count
Owner
County
County Highway Agency

About this bridge

Rocky Branch RD over Bayou Darbonne is a steel stringer/multi-beam or girder carrying Rocky Branch RD over Bayou Darbonne in Union Parish, Louisiana. It was built in 1974, so it is 51 years old, older than the Louisiana average of 43 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. Its operating status is: posted for load restriction.

It carries about 117 vehicles a day, projected to reach 128 by 2039. The structure is 723 ft (220.4 m) long and 24 ft wide. If it were closed, the detour would be 14.9 mi (24 km).

Location

Open in Google Maps
CarriesRocky Branch RD
CrossesBayou Darbonne
Location1.1 Mi. W. Int. 489
RouteCounty Highway 0
CountyUnion Parish
StateLouisiana
Coordinates32.67867, -92.23688
Functional classRural Local

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionMay 2024
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation3: Basically intolerable, requiring high priority of corrective action
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating16.8 US tons
Inventory rating11 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckWood or timber
Main spans31
Design loadHS 20
Structure length723 ft (220.4 m)
Longest span57 ft (17.4 m)
Deck width24 ft (7.3 m)
Roadway width23 ft (6.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic117 (2019)
Projected traffic128 by 2039
Trucks—
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed14.9 mi (24 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Rocky Branch RD over Bayou Darbonne built?

It was built in 1974, making it 51 years old in 2025.

What condition is Rocky Branch RD over Bayou Darbonne in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in May 2024.

How much traffic does Rocky Branch RD over Bayou Darbonne carry?

About 117 vehicles per day (2019 count).

How long is Rocky Branch RD over Bayou Darbonne?

The structure is 723 ft (220.4 m) long with a longest span of 57 ft (17.4 m) and a deck 24 ft wide.

Who owns Rocky Branch RD over Bayou Darbonne?

It is owned by the County Highway Agency.