US 78 over Polk Swamp
Dorchester County, South Carolina · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- US 78 over Polk Swamp in Dorchester County, South Carolina, 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 1949, making it 76 years old at the 2025 inventory.
- It carries about 4,700 vehicles a day (traffic count year 2023).
- Its listed owner is the state highway agency.
- It is one of 138 of the 199 inventoried bridges in Dorchester County rated fair (69.3%); 4 (2.0%) 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 → (33.2002, -80.62963)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 5 | Fair condition |
| Superstructure | 5 | Fair condition |
| Substructure | 7 | Good condition |
Bridge details
| Structure | Concrete slab |
| Length | about 111 ft |
| Location | 4 Mi NW of St George |
| NBI structure number | 000000000001621 |
| Condition class | Fair |
Source: FHWA National Bridge Inventory, 2025 data as reported by the South Carolina department of transportation.
Busiest bridges in Dorchester County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I-95 over Polk Swamp | 1974 | 50,100 | Fair |
| Sc 642 over Eagle Creek | 1956 | 40,300 | Fair |
| Sc 642 over Dorchester Creek | 1956 | 37,200 | Fair |
| Sc 165 over Julia Creek | 1997 | 34,500 | Fair |
| Sc 165 over RR NS & S-10-65 | 1998 | 34,500 | Good |
| S-18-230/ladson Rd over Chandler Bridge Creek | 2004 | 30,600 | Good |
All bridges nearby: Dorchester County, SC bridge conditions · every bridge in Dorchester County · South Carolina bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.