US 78
Carrying US 78 over FOUR HOLE SWAMP
3.8 MI NW OF RIDGEVILLE, Dorchester, South Carolina
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: US 78
The US 78 bridge in Dorchester, South Carolina carries US 78 over FOUR HOLE SWAMP. It was built in 1948, making it 78 years old today. The structure is built primarily of concrete and spans 17 sections, stretching 114.0 meters (374 feet) end to end. Daily traffic averages 7,900 vehicles, placing it in the moderately-trafficked tier of South Carolina bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show a deck rating of 5/9, superstructure at 5/9, substructure at 4/9. The weakest component sits in poor condition. A component scored 4 or below, placing this bridge in the federal Poor condition category rather than declaring it unsafe or closed. Its NBI inventory load rating is 28.8 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How US 78 compares
Live comparison across South Carolina.
Historical Sufficiency Rating
PlainBridge-computedFHWA discontinued this calculated item; it does not determine current condition, funding eligibility, posting, or closure. How the historical reference is calculated.
Condition Ratings
Full 0–9 scale + sufficiency-rating breakdown: how condition ratings work.
Structural Details
- Year Built
- 1948
- Material
- Concrete
- Number of Spans
- 17
- Structure Length
- 114.0 m (374 ft)
- Deck Width
- 9.8 m (32 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 7,900 vehicles/day
- Structure Number
- 000000000001454
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗Condition Analysis
- • The deck (driving surface) is in fair condition (5/9), with minor deterioration that may require routine maintenance.
- • The superstructure (beams and supports above the deck) rates fair at 5/9, minor deterioration that routine maintenance should address.
- • At 4/9, the substructure (piers and abutments) is in poor shape, with advanced wear flagged for priority repair.
How to read this record
US 78 is in the federal Poor condition category. That is a component-based result, not a closure order.
- NBI condition ratings reflect the latest record in this annual dataset, not a live status. Current routine inspection intervals are risk-based.
- Understand what Poor condition does and does not mean before drawing conclusions. Poor condition explained
- Compare US 78 against other structures in Dorchester and across South Carolina. South Carolina bridges
- Noticed visible damage or a safety concern? Report it to the agency that owns the bridge, or call 911 in an emergency. How to report a bridge
Condition codes come straight from the FHWA National Bridge Inventory and are not a real-time safety judgment. Only the owning agency, a state DOT, county, or other owner, can post, restrict, or close a bridge.
Frequently Asked Questions
What do the condition ratings mean for US 78?
US 78 in Dorchester, South Carolina has a deck rating of 5/9, superstructure rating of 5/9, and substructure rating of 4/9 on the FHWA's 0–9 scale.
How often is US 78 inspected?
US 78's responsible agency sets its routine interval under FHWA's risk-based inspection rules; this page does not expose the scheduled interval. It carries about 7,900 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. US 78 is currently shown as Poor condition from its component ratings; that category is not a live closure or safety decision.
What is the inventory load rating for US 78?
US 78 has an NBI inventory load rating of 28.8 metric tons.
Who is responsible for maintaining US 78?
US 78 is owned and maintained by State Highway Agency.
How old is US 78 and does age affect safety?
US 78 was built in 1948, making it 78 years old.
Disclaimer: Bridge condition data is from the FHWA NBI and reflects the last reported inspection. A Poor condition rating is not a live declaration that a bridge is closed or unsafe for travel. For current closure, posting, or safety information, contact the responsible transportation agency.
Every figure on PlainBridge is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.