Seaport Causeway over Biscayne Bay
Miami-Dade County, Florida · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Seaport Causeway over Biscayne Bay in Miami-Dade County, Florida, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1964, making it 61 years old at the 2025 inventory.
- It carries about 1 vehicles a day (traffic count year 2024).
- Its listed owner is the county highway agency.
- It is one of 269 of the 1,056 inventoried bridges in Miami-Dade County rated fair (25.5%); 55 (5.2%) 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 → (25.77921, -80.18225)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 5 | Fair condition |
| Superstructure | 5 | Fair condition |
| Substructure | 5 | Fair condition |
Bridge details
| Structure | Steel movable bascule |
| Length | about 2,238 ft |
| Location | Entrance to Port of Miami |
| NBI structure number | 874998 |
| Condition class | Fair |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Florida department of transportation.
Busiest bridges in Miami-Dade County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I-95 over NW 95 St | 1961 | 268,000 | Good |
| I-95 over SR932 (NW 103RD St) | 1961 | 268,000 | Good |
| I-95 over NW 111TH St | 1961 | 264,000 | Good |
| I-95 over 119TH St (SR-924) | 1962 | 264,000 | Good |
| SR-826 over Fec R/R Spur | 1960 | 250,000 | Good |
| SR-826 over US-27 & Miami Canal | 2006 | 250,000 | Good |
All bridges nearby: Miami-Dade County, FL bridge conditions · every bridge in Miami-Dade County · Florida bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.