US Bridges

Rocky Ridge Road ( over Monocacy River

Fair

Frederick County, Maryland · 1.3 MI W of Carroll CO · Structure no. 100000100055010

Built
1932
93 years old, rebuilt 2016
Condition
Fair
inspected August 2023
Type
Truss - Thru
Steel
Length
227 ft
2 main spans
Daily traffic
937
2023 count
Owner
State
State Highway Agency

About this bridge

Rocky Ridge Road ( over Monocacy River is a steel truss - thru carrying Rocky Ridge Road ( over Monocacy River in Frederick County, Maryland. It was built in 1932 and reconstructed in 2016, so it is 93 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 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 937 vehicles a day, roughly 13% of them trucks, projected to reach 1,143 by 2043. The structure is 227 ft (69.1 m) long and 29 ft wide. If it were closed, the detour would be 9.9 mi (16 km).

Location

Open in Google Maps
CarriesRocky Ridge Road (
CrossesMonocacy River
Location1.3 MI W of Carroll CO
RouteState Highway 77
CountyFrederick County
StateMaryland
Coordinates39.60346, -77.29351
Functional classRural Major 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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
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
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating88.5 US tons
Inventory rating53 US tons

Structure

Structure typeTruss - Thru
MaterialSteel
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length227 ft (69.1 m)
Longest span108 ft (32.9 m)
Deck width29 ft (8.8 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deck14 ft (4.3 m)

Traffic and service

Average daily traffic937 (2023)
Projected traffic1,143 by 2043
Trucks13%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed9.9 mi (16 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Rocky Ridge Road ( over Monocacy River built?

It was built in 1932, making it 93 years old in 2025. It was reconstructed in 2016.

What condition is Rocky Ridge Road ( over Monocacy 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 August 2023.

How much traffic does Rocky Ridge Road ( over Monocacy River carry?

About 937 vehicles per day (2023 count), of which roughly 13% are trucks.

How long is Rocky Ridge Road ( over Monocacy River?

The structure is 227 ft (69.1 m) long with a longest span of 108 ft (32.9 m) and a deck 29 ft wide.

Who owns Rocky Ridge Road ( over Monocacy River?

It is owned by the State Highway Agency.