US Bridges

E 9th Avenue over Oligarchy Ditch

Fair

Boulder County, Colorado · 100 Ft E of Alpine Street · Structure no. LONG-E9TH-ALP-A

Built
2004
21 years old
Condition
Fair
inspected January 2025
Type
Culvert
Concrete
Length
82 ft
3 main spans
Daily traffic
12,630
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

E 9th Avenue over Oligarchy Ditch is a concrete culvert carrying E 9th Avenue over Oligarchy Ditch in Boulder County, Colorado. It was built in 2004, so it is 21 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 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 12,630 vehicles a day, roughly 10% of them trucks, projected to reach 15,156 by 2043. The structure is 82 ft (25.1 m) long and 88 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesE 9th Avenue
CrossesOligarchy Ditch
Location100 Ft E of Alpine Street
RouteCity Street 0
CountyBoulder County
StateColorado
Coordinates40.17388, -105.08188
Functional classUrban Minor Arterial

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 protection8 Very GoodNo problems noted.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJanuary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating40 US tons
Inventory rating36 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans3
Design loadHS 20
Structure length82 ft (25.1 m)
Longest span24 ft (7.3 m)
Deck width88 ft (26.9 m)
Roadway width65 ft (19.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic12,630 (2023)
Projected traffic15,156 by 2043
Trucks10%
Lanes on structure5
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was E 9th Avenue over Oligarchy Ditch built?

It was built in 2004, making it 21 years old in 2025.

What condition is E 9th Avenue over Oligarchy Ditch 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 January 2025.

How much traffic does E 9th Avenue over Oligarchy Ditch carry?

About 12,630 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is E 9th Avenue over Oligarchy Ditch?

The structure is 82 ft (25.1 m) long with a longest span of 24 ft (7.3 m) and a deck 88 ft wide.

Who owns E 9th Avenue over Oligarchy Ditch?

It is owned by the City or Municipal Highway Agency.