US Bridges

IRR/US-491 over Pena Blanca Arroyo

Fair

San Juan County, New Mexico · 1.86 MI N RD to Toadlena · Structure no. 000000000008043

Built
1980
45 years old
Condition
Fair
inspected August 2023
Type
Slab
Concrete Continuous
Length
130 ft
4 main spans
Daily traffic
6,055
2023 count
Owner
State
State Highway Agency

About this bridge

IRR/US-491 over Pena Blanca Arroyo is a concrete continuous slab carrying IRR/US-491 over Pena Blanca Arroyo in San Juan County, New Mexico. It was built in 1980, so it is 45 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 6,055 vehicles a day, roughly 17% of them trucks, projected to reach 8,234 by 2043. The structure is 130 ft (39.6 m) long and 47 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesIRR/US-491
CrossesPena Blanca Arroyo
Location1.86 MI N RD to Toadlena
RouteU.S. Route 491
CountySan Juan County
StateNew Mexico
Coordinates36.3592, -108.7206
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: 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 rating63.9 US tons
Inventory rating38.1 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length130 ft (39.6 m)
Longest span36 ft (11 m)
Deck width47 ft (14.3 m)
Roadway width44 ft (13.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,055 (2023)
Projected traffic8,234 by 2043
Trucks17%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkNon-Interstate 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$449,000 (2020 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was IRR/US-491 over Pena Blanca Arroyo built?

It was built in 1980, making it 45 years old in 2025.

What condition is IRR/US-491 over Pena Blanca 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 August 2023.

How much traffic does IRR/US-491 over Pena Blanca Arroyo carry?

About 6,055 vehicles per day (2023 count), of which roughly 17% are trucks.

How long is IRR/US-491 over Pena Blanca Arroyo?

The structure is 130 ft (39.6 m) long with a longest span of 36 ft (11 m) and a deck 47 ft wide.

Who owns IRR/US-491 over Pena Blanca Arroyo?

It is owned by the State Highway Agency.