US Bridges

N21 over Wood River Trib

Good

Custer County, Nebraska · 1S Oconto · Structure no. S021 05160

Built
1962
63 years old, rebuilt 2021
Condition
Good
inspected November 2024
Type
Tee Beam
Prestressed Concrete Continuous
Length
82 ft
3 main spans
Daily traffic
920
2018 count
Owner
State
State Highway Agency

About this bridge

N21 over Wood River Trib is a prestressed concrete continuous tee beam carrying N21 over Wood River Trib in Custer County, Nebraska. It was built in 1962 and reconstructed in 2021, so it is 63 years old, older than the Nebraska average of 47.1 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 920 vehicles a day, roughly 26% of them trucks, projected to reach 1,196 by 2038. The structure is 82 ft (25 m) long and 38 ft wide. If it were closed, the detour would be 18.6 mi (30 km).

CarriesN21
CrossesWood River Trib
Location1S Oconto
RouteState Highway 21
Coordinates41.1234, -99.76025
Functional classRural Minor Arterial

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating86 US tons
Inventory rating47.4 US tons

Structure

Structure typeTee Beam
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHL 93
Structure length82 ft (25 m)
Longest span32 ft (9.9 m)
Deck width38 ft (11.5 m)
Roadway width36 ft (10.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic920 (2018)
Projected traffic1,196 by 2038
Trucks26%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed18.6 mi (30 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 with deck rehabilitation or replacement
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was N21 over Wood River Trib built?

It was built in 1962, making it 63 years old in 2025. It was reconstructed in 2021.

What condition is N21 over Wood River Trib in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in November 2024.

How much traffic does N21 over Wood River Trib carry?

About 920 vehicles per day (2018 count), of which roughly 26% are trucks.

How long is N21 over Wood River Trib?

The structure is 82 ft (25 m) long with a longest span of 32 ft (9.9 m) and a deck 38 ft wide.

Who owns N21 over Wood River Trib?

It is owned by the State Highway Agency.