US Bridges

Md 320 over Sligo Creek

Fair

Montgomery County, Maryland · 0.69 Mile South of Md 193 · Structure no. 100000150051010

Built
1920
105 years old, rebuilt 1933
Condition
Fair
inspected August 2023
Type
Tee Beam
Concrete
Length
45 ft
2 main spans
Daily traffic
19,392
2009 count
Owner
State
State Highway Agency

About this bridge

Md 320 over Sligo Creek is a concrete tee beam carrying Md 320 over Sligo Creek in Montgomery County, Maryland. It was built in 1920 and reconstructed in 1933, so it is 105 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 19,392 vehicles a day, roughly 8% of them trucks, projected to reach 25,288 by 2026. The structure is 45 ft (13.7 m) long and 53 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
CarriesMd 320
CrossesSligo Creek
Location0.69 Mile South of Md 193
RouteState Highway 320
CountyMontgomery County
StateMaryland
Coordinates38.99563, -77.00625
Functional classUrban Minor Arterial

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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourCountermeasures installed to correct a previously existing problem
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 alignment6: Equal to present minimum criteria
Operating rating86 US tons
Inventory rating51.5 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckConcrete, cast-in-place
Main spans2
Design loadUnknown
Structure length45 ft (13.7 m)
Longest span20 ft (6.1 m)
Deck width53 ft (16.1 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic19,392 (2009)
Projected traffic25,288 by 2026
Trucks8%
Lanes on structure3
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed6.2 mi (10 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedWidening of existing bridge without deck rehabilitation
Estimated improvement cost$157,000
NavigationNo navigation control on waterway

Frequently asked questions

When was Md 320 over Sligo Creek built?

It was built in 1920, making it 105 years old in 2025. It was reconstructed in 1933.

What condition is Md 320 over Sligo Creek 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 August 2023.

How much traffic does Md 320 over Sligo Creek carry?

About 19,392 vehicles per day (2009 count), of which roughly 8% are trucks.

How long is Md 320 over Sligo Creek?

The structure is 45 ft (13.7 m) long with a longest span of 20 ft (6.1 m) and a deck 53 ft wide.

Who owns Md 320 over Sligo Creek?

It is owned by the State Highway Agency.