US Bridges

N. Bayou Black Dr. over Donner Canal

Good

Terrebonne Parish, Louisiana · 1.2 MI NW of LA.20 · Structure no. 025500000020554

Built
2017
8 years old
Condition
Good
inspected April 2023
Type
Truss - Thru
Steel
Length
70 ft
1 main span
Daily traffic
1,256
2020 count
Owner
County
County Highway Agency

About this bridge

N. Bayou Black Dr. over Donner Canal is a steel truss - thru carrying N. Bayou Black Dr. over Donner Canal in Terrebonne Parish, Louisiana. It was built in 2017, so it is 8 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 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 1,256 vehicles a day, projected to reach 1,381 by 2040. The structure is 70 ft (21.3 m) long and 29 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesN. Bayou Black Dr.
CrossesDonner Canal
Location1.2 MI NW of LA.20
RouteCounty Highway 0
CountyTerrebonne Parish
StateLouisiana
Coordinates29.67707, -90.9785
Functional classRural Local

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection7 GoodSome minor problems.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation8: Equal to present desirable criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating72 US tons
Inventory rating43 US tons

Structure

Structure typeTruss - Thru
MaterialSteel
DeckSteel plate
Main spans1
Design loadHS 20
Structure length70 ft (21.3 m)
Longest span70 ft (21.3 m)
Deck width29 ft (8.8 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,256 (2020)
Projected traffic1,381 by 2040
Trucks—
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 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 N. Bayou Black Dr. over Donner Canal built?

It was built in 2017, making it 8 years old in 2025.

What condition is N. Bayou Black Dr. over Donner Canal 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 2023.

How much traffic does N. Bayou Black Dr. over Donner Canal carry?

About 1,256 vehicles per day (2020 count).

How long is N. Bayou Black Dr. over Donner Canal?

The structure is 70 ft (21.3 m) long with a longest span of 70 ft (21.3 m) and a deck 29 ft wide.

Who owns N. Bayou Black Dr. over Donner Canal?

It is owned by the County Highway Agency.