US Bridges

Flag Marsh Road over South Br Patapsco River

Fair

Carroll County, Maryland · On Howard CO Line · Structure no. 200000CL0309020

Built
1988
37 years old
Condition
Fair
inspected July 2023
Type
Culvert
Concrete
Length
43 ft
Daily traffic
747
2021 count
Owner
County
County Highway Agency

About this bridge

Flag Marsh Road over South Br Patapsco River is a concrete culvert carrying Flag Marsh Road over South Br Patapsco River in Carroll County, Maryland. It was built in 1988, so it is 37 years old, younger 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 6 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 747 vehicles a day, roughly 5% of them trucks, projected to reach 1,225 by 2041. The structure is 43 ft (13.1 m) long and 39 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

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CarriesFlag Marsh Road
CrossesSouth Br Patapsco River
LocationOn Howard CO Line
RouteCounty Highway 599
CountyCarroll County
StateMaryland
Coordinates39.36244, -77.06621
Functional classRural Local

Condition and inspection

Fair

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

ComponentRatingMeaning
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating110.1 US tons
Inventory rating110.1 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans0
Design loadUnknown
Structure length43 ft (13.1 m)
Longest span21 ft (6.4 m)
Deck width39 ft (11.8 m)
Roadway width37 ft (11.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic747 (2021)
Projected traffic1,225 by 2041
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Flag Marsh Road over South Br Patapsco River built?

It was built in 1988, making it 37 years old in 2025.

What condition is Flag Marsh Road over South Br Patapsco River 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 July 2023.

How much traffic does Flag Marsh Road over South Br Patapsco River carry?

About 747 vehicles per day (2021 count), of which roughly 5% are trucks.

How long is Flag Marsh Road over South Br Patapsco River?

The structure is 43 ft (13.1 m) long with a longest span of 21 ft (6.4 m) and a deck 39 ft wide.

Who owns Flag Marsh Road over South Br Patapsco River?

It is owned by the County Highway Agency.