US Bridges

N3940 over Lake Copan

Fair

Washington County, Oklahoma · 3. W 3.7 N of US 75 · Structure no. 177050000000000

Built
1970
55 years old
Condition
Fair
inspected October 2024
Type
Culvert
Concrete
Length
32 ft
3 main spans
Daily traffic
100
2022 count
Owner
County
County Highway Agency

About this bridge

N3940 over Lake Copan is a concrete culvert carrying N3940 over Lake Copan in Washington County, Oklahoma. It was built in 1970, so it is 55 years old, older than the Oklahoma average of 47.8 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 100 vehicles a day, roughly 10% of them trucks, projected to reach 160 by 2042. The structure is 32 ft (9.8 m) long. If it were closed, the detour would be 21.7 mi (35 km).

Location

Open in Google Maps
CarriesN3940
CrossesLake Copan
Location3. W 3.7 N of US 75
RouteCounty Highway N3940
CountyWashington County
StateOklahoma
Coordinates36.95028, -95.9673
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 protection7 GoodSome minor problems.
Culvert5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating36 US tons
Inventory rating21.6 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans3
Design loadHS 20
Structure length32 ft (9.8 m)
Longest span10 ft (3 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic100 (2022)
Projected traffic160 by 2042
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed21.7 mi (35 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 proposedWidening of existing bridge without deck rehabilitation
Estimated improvement cost$225,000
NavigationNo navigation control on waterway

Frequently asked questions

When was N3940 over Lake Copan built?

It was built in 1970, making it 55 years old in 2025.

What condition is N3940 over Lake Copan 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 N3940 over Lake Copan carry?

About 100 vehicles per day (2022 count), of which roughly 10% are trucks.

How long is N3940 over Lake Copan?

The structure is 32 ft (9.8 m) long with a longest span of 10 ft (3 m).

Who owns N3940 over Lake Copan?

It is owned by the County Highway Agency.