US Bridges

US 15 Bu over Flat Run

Fair

Frederick County, Maryland · 0.75 Mile South of US 15 · Structure no. 100000100001010

Built
1927
98 years old
Condition
Fair
inspected October 2024
Type
Arch - Deck
Concrete
Length
50 ft
1 main span
Daily traffic
1,820
2009 count
Owner
State
State Highway Agency

About this bridge

US 15 Bu over Flat Run is a concrete arch - deck carrying US 15 Bu over Flat Run in Frederick County, Maryland. It was built in 1927, so it is 98 years old, older than the Maryland average of 52.6 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 1,820 vehicles a day, roughly 8% of them trucks, projected to reach 2,260 by 2026. The structure is 50 ft (15.2 m) long and 27 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesUS 15 Bu
CrossesFlat Run
Location0.75 Mile South of US 15
RouteU.S. Route 15
CountyFrederick County
StateMaryland
Coordinates39.70846, -77.3217
Functional classRural Minor Collector

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating110.1 US tons
Inventory rating89.9 US tons

Structure

Structure typeArch - Deck
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadUnknown
Structure length50 ft (15.2 m)
Longest span50 ft (15.2 m)
Deck width27 ft (8.3 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,820 (2009)
Projected traffic2,260 by 2026
Trucks8%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusPossibly eligible for the National Register; requires further investigation
Work proposedWidening of existing bridge without deck rehabilitation
Estimated improvement cost$94,000
NavigationNo navigation control on waterway

Frequently asked questions

When was US 15 Bu over Flat Run built?

It was built in 1927, making it 98 years old in 2025.

What condition is US 15 Bu over Flat Run in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in October 2024.

How much traffic does US 15 Bu over Flat Run carry?

About 1,820 vehicles per day (2009 count), of which roughly 8% are trucks.

How long is US 15 Bu over Flat Run?

The structure is 50 ft (15.2 m) long with a longest span of 50 ft (15.2 m) and a deck 27 ft wide.

Who owns US 15 Bu over Flat Run?

It is owned by the State Highway Agency.