US Bridges

US-491 over Malpas Arroyo

Fair

San Juan County, New Mexico · 8.3 MI N of JCT US-64 · Structure no. 000000000007957

Built
1978
47 years old
Condition
Fair
inspected May 2021
Type
Culvert
Concrete
Length
26 ft
2 main spans
Daily traffic
4,224
2023 count
Owner
State
State Highway Agency

About this bridge

US-491 over Malpas Arroyo is a concrete culvert carrying US-491 over Malpas Arroyo in San Juan County, New Mexico. It was built in 1978, so it is 47 years old, younger 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 4,224 vehicles a day, roughly 17% of them trucks, projected to reach 5,744 by 2043. The structure is 26 ft (8 m) long. If it were closed, the detour would be 49.7 mi (80 km).

Location

Open in Google Maps
CarriesUS-491
CrossesMalpas Arroyo
Location8.3 MI N of JCT US-64
RouteU.S. Route 491
CountySan Juan County
StateNew Mexico
Coordinates36.90095, -108.71711
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 protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMay 2021
Inspection intervalevery 48 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 rating98.2 US tons
Inventory rating35.7 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans2
Design loadHS 20
Structure length26 ft (8 m)
Longest span12 ft (3.7 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,224 (2023)
Projected traffic5,744 by 2043
Trucks17%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed49.7 mi (80 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$294,000 (2030 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was US-491 over Malpas Arroyo built?

It was built in 1978, making it 47 years old in 2025.

What condition is US-491 over Malpas Arroyo 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 May 2021.

How much traffic does US-491 over Malpas Arroyo carry?

About 4,224 vehicles per day (2023 count), of which roughly 17% are trucks.

How long is US-491 over Malpas Arroyo?

The structure is 26 ft (8 m) long with a longest span of 12 ft (3.7 m).

Who owns US-491 over Malpas Arroyo?

It is owned by the State Highway Agency.