Structure C-15-U · Larimer County, CO

US 34 Ml over Big Thompson River

Carries US 34 Ml over Big Thompson River, 6.5 Mi E Of Estes Park.

Overall conditionGood

Set by its lowest-rated component: Deck and Superstructure and Substructure at 7 of 9.

How ratings work
Decksets the rating7/9 · Good
Superstructuresets the rating7/9 · Good
Substructuresets the rating7/9 · Good
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT128 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 7/9

128 ft end to end. Lengths and the semi-truck 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.

Built200323 years old
Length128.3 ft39.1 m
Daily traffic5,800counted 2020
Last inspectedSeptember 2023every 24 months

Location

StateColorado
CountyLarimer
Location6.5 Mi E Of Estes Park
CarriesUS 34 Ml
CrossesBig Thompson River
Coordinates40.40780, -105.40820

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length128.3 ft (39.1 m)
Max Span125.0 ft (38.1 m)
Deck Width43.0 ft (13.1 m)
Deck Area512.2 sq m
Main Spans1
Year Built2003

Traffic

Avg Daily Traffic5,800 (2020)
Truck Traffic2%
Lanes On Bridge2

Inspection & Ownership

Last InspectionSeptember 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is possibly eligible (requires evaluation)
Scour Critical8 — Stable, low risk
Structure NumberC-15-U

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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