US Bridges

IRR/US-491 over Unnamed Waterway

Fair

San Juan County, New Mexico · 40.3 MI N of JCT I-40 · Structure no. 000000000007438

Built
1973
52 years old
Condition
Fair
inspected September 2023
Type
Culvert
Steel
Length
40 ft
1 main span
Daily traffic
5,936
2023 count
Owner
State
State Highway Agency

About this bridge

IRR/US-491 over Unnamed Waterway is a steel culvert carrying IRR/US-491 over Unnamed Waterway in San Juan County, New Mexico. It was built in 1973, so it is 52 years old, older than the New Mexico average of 51.5 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 5,936 vehicles a day, roughly 17% of them trucks, projected to reach 8,072 by 2043. The structure is 40 ft (12.2 m) long. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesIRR/US-491
CrossesUnnamed Waterway
Location40.3 MI N of JCT I-40
RouteU.S. Route 491
CountySan Juan County
StateNew Mexico
Coordinates36.04918, -108.67674
Functional classRural Principal Arterial - Other

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.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating89.3 US tons
Inventory rating35.7 US tons

Structure

Structure typeCulvert
MaterialSteel
DeckNot applicable
Main spans1
Design loadHS 20
Structure length40 ft (12.2 m)
Longest span35 ft (10.7 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,936 (2023)
Projected traffic8,072 by 2043
Trucks17%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$547,000 (2020 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was IRR/US-491 over Unnamed Waterway built?

It was built in 1973, making it 52 years old in 2025.

What condition is IRR/US-491 over Unnamed Waterway 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 September 2023.

How much traffic does IRR/US-491 over Unnamed Waterway carry?

About 5,936 vehicles per day (2023 count), of which roughly 17% are trucks.

How long is IRR/US-491 over Unnamed Waterway?

The structure is 40 ft (12.2 m) long with a longest span of 35 ft (10.7 m).

Who owns IRR/US-491 over Unnamed Waterway?

It is owned by the State Highway Agency.