Causeway SB over Lake Pontchartrain
St. Tammany Parish, Louisiana · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Causeway SB over Lake Pontchartrain in St. Tammany Parish, Louisiana, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the superstructure, rated 6 (satisfactory condition) on the 0-9 scale.
- It was built in 1956, making it 69 years old at the 2025 inventory.
- It carries about 18,830 vehicles a day (traffic count year 1987).
- It is one of 220 of the 361 inventoried bridges in St. Tammany Parish rated fair (60.9%); 18 (5.0%) are rated poor.
- 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 → (30.36399, -90.09405)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 7 | Good condition |
| Superstructure | 6 | Satisfactory condition |
| Substructure | 6 | Satisfactory condition |
Bridge details
| Structure | Steel movable bascule |
| Length | about 127,200 ft |
| Location | Causeway Southbound |
| NBI structure number | 625230123900731 |
| Condition class | Fair |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Louisiana department of transportation.
Busiest bridges in St. Tammany Parish
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I0010 over East Pearl River | 1966 | 87,741 | Fair |
| I0010 over La 433 | 1966 | 82,860 | Fair |
| I0010 over Canal | 1966 | 82,860 | Fair |
| I0012 over La 59 | 1976 | 80,162 | Good |
| I0012 over Ponchatolawa Creek | 1976 | 79,960 | Fair |
| I0012 over Tchefuncte River | 1975 | 79,563 | Fair |
All bridges nearby: St. Tammany Parish, LA bridge conditions · every bridge in St. Tammany Parish · Louisiana bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.