US Bridges

N3100 over Blair Branch

FairPosted for load

Carter County, Oklahoma · 1E&.7N of JCTSH76 & SH53E · Structure no. 234720000000000

Built
1993
32 years old
Condition
Fair
inspected March 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
40 ft
1 main span
Daily traffic
50
2022 count
Owner
County
County Highway Agency

About this bridge

N3100 over Blair Branch is a steel stringer/multi-beam or girder carrying N3100 over Blair Branch in Carter County, Oklahoma. It was built in 1993, so it is 32 years old, younger 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. Its operating status is: posted for load restriction.

It carries about 50 vehicles a day, roughly 10% of them trucks, projected to reach 80 by 2042. The structure is 40 ft (12.2 m) long and 26 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesN3100
CrossesBlair Branch
Location1E&.7N of JCTSH76 & SH53E
RouteCounty Highway 3100
CountyCarter County
StateOklahoma
Coordinates34.35721, -97.47494
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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionMarch 2023
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating38 US tons
Inventory rating23 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length40 ft (12.2 m)
Longest span38 ft (11.6 m)
Deck width26 ft (7.9 m)
Roadway width26 ft (7.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic50 (2022)
Projected traffic80 by 2042
Trucks10%
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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$311,000
NavigationNo navigation control on waterway

Frequently asked questions

When was N3100 over Blair Branch built?

It was built in 1993, making it 32 years old in 2025.

What condition is N3100 over Blair Branch 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 March 2023.

How much traffic does N3100 over Blair Branch carry?

About 50 vehicles per day (2022 count), of which roughly 10% are trucks.

How long is N3100 over Blair Branch?

The structure is 40 ft (12.2 m) long with a longest span of 38 ft (11.6 m) and a deck 26 ft wide.

Who owns N3100 over Blair Branch?

It is owned by the County Highway Agency.