US Bridges

County Road 4A over San Miguel River

Fair

Montrose County, Colorado · .2 MI N of CR 90 · Structure no. 085004A00.5013A

Built
1985
40 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
82 ft
1 main span
Daily traffic
586
2022 count
Owner
County
County Highway Agency

About this bridge

County Road 4A over San Miguel River is a steel stringer/multi-beam or girder carrying County Road 4A over San Miguel River in Montrose County, Colorado. It was built in 1985, so it is 40 years old, younger than the Colorado average of 42.2 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.

It carries about 586 vehicles a day, roughly 5% of them trucks, projected to reach 680 by 2042. The structure is 82 ft (25 m) long and 29 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

Open in Google Maps
CarriesCounty Road 4A
CrossesSan Miguel River
Location.2 MI N of CR 90
RouteCounty Highway 0
CountyMontrose County
StateColorado
Coordinates38.2407, -108.50717
Functional classRural Major Collector

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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 protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating42.5 US tons
Inventory rating25.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadHS 20
Structure length82 ft (25 m)
Longest span78 ft (23.9 m)
Deck width29 ft (8.8 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic586 (2022)
Projected traffic680 by 2042
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was County Road 4A over San Miguel River built?

It was built in 1985, making it 40 years old in 2025.

What condition is County Road 4A over San Miguel River 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 County Road 4A over San Miguel River carry?

About 586 vehicles per day (2022 count), of which roughly 5% are trucks.

How long is County Road 4A over San Miguel River?

The structure is 82 ft (25 m) long with a longest span of 78 ft (23.9 m) and a deck 29 ft wide.

Who owns County Road 4A over San Miguel River?

It is owned by the County Highway Agency.