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I-25 NBL and SBL over Alkali Creek

Converse County, Wyoming · rated Fair in the 2025 National Bridge Inventory

United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled August 20, 2026

I-25 NBL and SBL over Alkali Creek in Converse County, Wyoming, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the culvert, rated 5 (fair condition) on the 0-9 scale.
It was built in 1958, making it 67 years old at the 2025 inventory.
It carries about 4,607 vehicles a day (traffic count year 2024).
Its listed owner is the state highway agency.
It is one of 96 of the 136 inventoried bridges in Converse County rated fair (70.6%); 19 (14.0%) are rated poor.
A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.

Component ratings

Component	Rating (2025)	FHWA scale meaning
Culvert	5	Fair condition


Structure	Continuous concrete culvert
Length	about 20 ft
Location	Douglas - Casper
NBI structure number	AGL
Condition class	Fair

Source: FHWA National Bridge Inventory, 2025 data as reported by the Wyoming department of transportation.

Bridge	Built	Vehicles/day	Condition
I25/US20-26-87 Bus over North Platte River	2009	8,403	Good
I25/US20-26-87 Bus over I-25	1966	7,719	Fair
Wyo 59 over North Platte River	1988	6,320	Good
Wyo 59 over BNSF Railway	1988	6,320	Fair
W Richards Street over North Platte River	1984	5,816	Poor
I-25 Sbl over Wyo 90	1967	4,838	Fair