St. Charles Bypass over Grand Coteau Bayou
Lafourche Parish, Louisiana · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- St. Charles Bypass over Grand Coteau Bayou in Lafourche Parish, Louisiana, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the substructure, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1970, making it 55 years old at the 2025 inventory.
- It carries about 1,193 vehicles a day (traffic count year 2020).
- Its listed owner is the county highway agency.
- It is one of 59 of the 130 inventoried bridges in Lafourche Parish rated fair (45.4%); 20 (15.4%) are rated poor.
- Its traffic status in the 2025 inventory is posted for load (NBI item 41).
- Its condition class and component ratings are unchanged from the 2024 inventory.
- Its most recent inspection on record is dated June 2023, on a 12-month routine inspection cycle.
- A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.
View this bridge on a map → (29.73327, -90.7347)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 6 | 6 | Satisfactory condition |
| Superstructure | 6 | 6 | Satisfactory condition |
| Substructure | 5 | 5 | Fair condition |
Bridge details
| Structure | Concrete slab |
| Length | about 76 ft |
| Location | 0148 Log Mi From Int |
| NBI structure number | 022929440904411 |
| Condition class | Fair |
| Traffic status (item 41) | Posted for load |
| Last inspection (item 90) | June 2023 |
| Inspection interval (item 91) | 12 months |
| Scour (item 113) | 8: foundations stable, scour above the top of the footing |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Louisiana department of transportation.
Busiest bridges in Lafourche Parish
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US0090 over Drainage Canal | 1976 | 27,665 | Fair |
| US0090 over Drainage Canal | 1976 | 27,665 | Good |
| US0090 over on Ramp From LA308 | 1976 | 26,058 | Good |
| LA0020 over 40 Arpent Canal | 1968 | 20,091 | Fair |
| LA0020 over Drainage Canal | 1968 | 20,091 | Good |
| LA0020 over Drainage Canal | 1968 | 20,091 | Poor |
All bridges nearby: Lafourche Parish, LA bridge conditions · every bridge in Lafourche Parish · Louisiana bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.