US Bridges

Dan Mcnamara Road over Duck Slough

Fair

Merced County, California · 1.5 MI N Sandy Mush Road · Structure no. 39C0285

Built
1982
43 years old
Condition
Fair
inspected November 2024
Type
Culvert
Steel
Length
21 ft
3 main spans
Daily traffic
75
1990 count
Owner
County
County Highway Agency

About this bridge

Dan Mcnamara Road over Duck Slough is a steel culvert carrying Dan Mcnamara Road over Duck Slough in Merced County, California. It was built in 1982, so it is 43 years old, younger than the California average of 54.8 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 75 vehicles a day, roughly 3% of them trucks, projected to reach 209 by 2042. The structure is 21 ft (6.4 m) long. If it were closed, the detour would be 16.8 mi (27 km).

Location

Open in Google Maps
CarriesDan Mcnamara Road
CrossesDuck Slough
Location1.5 MI N Sandy Mush Road
RouteCounty Highway 0
CountyMerced County
StateCalifornia
Coordinates37.20795, -120.67065
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
Channel and channel protection7 GoodSome minor problems.
Culvert5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionNovember 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
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating44.3 US tons
Inventory rating34.3 US tons

Structure

Structure typeCulvert
MaterialSteel
DeckNot applicable
Main spans3
Design loadUnknown
Structure length21 ft (6.4 m)
Longest span7 ft (2.1 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic75 (1990)
Projected traffic209 by 2042
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed16.8 mi (27 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 Dan Mcnamara Road over Duck Slough built?

It was built in 1982, making it 43 years old in 2025.

What condition is Dan Mcnamara Road over Duck Slough 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 November 2024.

How much traffic does Dan Mcnamara Road over Duck Slough carry?

About 75 vehicles per day (1990 count), of which roughly 3% are trucks.

How long is Dan Mcnamara Road over Duck Slough?

The structure is 21 ft (6.4 m) long with a longest span of 7 ft (2.1 m).

Who owns Dan Mcnamara Road over Duck Slough?

It is owned by the County Highway Agency.