Structure M-23-I · Otero County, CO

SH 109 Ml over Mcmahon Arroyo

Carries SH 109 Ml over Mcmahon Arroyo, 8.5 Miles No Of Bent-oter.

Overall conditionFair

Set by its lowest-rated component: Superstructure at 6 of 9.

How ratings work
Deck7/9 · Good
Superstructuresets the rating6/9 · Satisfactory
Substructure7/9 · Good
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT94 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 6/9 · sets the ratingSubstructure 7/9

94 ft end to end, longest span 45 ft. Lengths and the car on the deck are drawn to the same scale. Each part is colored by its latest inspection rating. The inventory records lengths but not heights or the layout of the shorter spans, so those are drawn as typical for a multi-beam bridge.

Built197254 years old
Length94.2 ft28.7 m
Daily traffic350counted 2020
Last inspectedJune 2024every 24 months

Location

StateColorado
CountyOtero
Location8.5 Miles No Of Bent-oter
CarriesSH 109 Ml
CrossesMcmahon Arroyo
Coordinates37.77617, -103.45859

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length94.2 ft (28.7 m)
Max Span44.6 ft (13.6 m)
Deck Width34.4 ft (10.5 m)
Deck Area301.4 sq m
Main Spans2
Year Built1972

Traffic

Avg Daily Traffic350 (2020)
Truck Traffic17%
Lanes On Bridge2

Inspection & Ownership

Last InspectionJune 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure NumberM-23-I

How Bridge Ratings Work

Inspectors rate each major part of a bridge (the deck you drive on, the superstructure of beams that holds it up, and the substructure of piers and abutments beneath) on a 0–9 scale. A bridge's overall condition is its lowest of those ratings, so one deteriorated component makes the whole bridge "poor."

0Failed
1Imminent failure
2Critical
3Serious
4Poor
5Fair
6Satisfactory
7Good
8Very good
9Excellent
Good · lowest component 7–9
Fair · lowest component 5–6
Poor · lowest component 0–4

A poor rating is not a closure. It means the bridge is flagged for priority repair or replacement; bridges judged unsafe are closed or posted with weight limits. The waterway (channel) rating is reported, but it does not count toward the overall classification.

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