US Bridges

SH 55 Ml over South Platte River

Good

Logan County, Colorado · 1.5 MI S of JCT SH55+US13 · Structure no. A-25-AU

Built
1987
38 years old
Condition
Good
inspected June 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
180 ft
2 main spans
Daily traffic
460
2020 count
Owner
State
State Highway Agency

About this bridge

SH 55 Ml over South Platte River is a steel continuous stringer/multi-beam or girder carrying SH 55 Ml over South Platte River in Logan County, Colorado. It was built in 1987, so it is 38 years old, younger than the Colorado average of 42.2 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 460 vehicles a day, roughly 18% of them trucks, projected to reach 833 by 2040. The structure is 180 ft (54.9 m) long and 36 ft wide. If it were closed, the detour would be 16.2 mi (26 km).

CarriesSH 55 Ml
CrossesSouth Platte River
Location1.5 MI S of JCT SH55+US13
RouteState Highway 55A
Coordinates40.8365, -102.80493
Functional classRural Major Collector

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJune 2023
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating54.2 US tons
Inventory rating32.4 US tons

Structure

MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20 + Mod
Structure length180 ft (54.9 m)
Longest span89 ft (27.1 m)
Deck width36 ft (11.1 m)
Roadway width34 ft (10.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic460 (2020)
Projected traffic833 by 2040
Trucks18%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed16.2 mi (26 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState 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 SH 55 Ml over South Platte River built?

It was built in 1987, making it 38 years old in 2025.

What condition is SH 55 Ml over South Platte River in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in June 2023.

How much traffic does SH 55 Ml over South Platte River carry?

About 460 vehicles per day (2020 count), of which roughly 18% are trucks.

How long is SH 55 Ml over South Platte River?

The structure is 180 ft (54.9 m) long with a longest span of 89 ft (27.1 m) and a deck 36 ft wide.

Who owns SH 55 Ml over South Platte River?

It is owned by the State Highway Agency.