US Bridges

County Road 18 over Mallon Ditch

Fair

Jackson County, Colorado · 3.3 MI W of CO RD 12W · Structure no. 57001803.30028

Built
1986
39 years old
Condition
Fair
inspected November 2024
Type
Arch - Thru
Steel
Length
24 ft
1 main span
Daily traffic
146
2023 count
Owner
County
County Highway Agency

About this bridge

County Road 18 over Mallon Ditch is a steel arch - thru carrying County Road 18 over Mallon Ditch in Jackson County, Colorado. It was built in 1986, so it is 39 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 146 vehicles a day, roughly 16% of them trucks, projected to reach 190 by 2043. The structure is 24 ft (7.2 m) long and 43 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesCounty Road 18
CrossesMallon Ditch
Location3.3 MI W of CO RD 12W
RouteCounty Highway 0
CountyJackson County
StateColorado
Coordinates40.69442, -106.44163
Functional classRural Minor 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
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure8 Very GoodNo problems noted.
Channel and channel protection7 GoodSome minor problems.
Last inspectionNovember 2024
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 geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating48 US tons
Inventory rating36 US tons

Structure

Structure typeArch - Thru
MaterialSteel
DeckNot applicable
Main spans1
Design loadHS 20
Structure length24 ft (7.2 m)
Longest span24 ft (7.2 m)
Deck width43 ft (13.2 m)
Roadway width32 ft (9.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic146 (2023)
Projected traffic190 by 2043
Trucks16%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 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 18 over Mallon Ditch built?

It was built in 1986, making it 39 years old in 2025.

What condition is County Road 18 over Mallon 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 November 2024.

How much traffic does County Road 18 over Mallon Ditch carry?

About 146 vehicles per day (2023 count), of which roughly 16% are trucks.

How long is County Road 18 over Mallon Ditch?

The structure is 24 ft (7.2 m) long with a longest span of 24 ft (7.2 m) and a deck 43 ft wide.

Who owns County Road 18 over Mallon Ditch?

It is owned by the County Highway Agency.