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18 Mile Road over Eighteen Mile Creek

Lemhi County, Idaho · rated Good in the 2025 National Bridge Inventory

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

18 Mile Road over Eighteen Mile Creek in Lemhi County, Idaho, is rated in good condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the deck, rated 8 (very good condition) on the 0-9 scale.
It was built in 2020, making it 5 years old at the 2025 inventory.
It carries about 20 vehicles a day (traffic count year 2023).
Its listed owner is the county highway agency.
It is one of 65 of the 114 inventoried bridges in Lemhi County rated good (57.0%); 9 (7.9%) are rated poor.
A good rating means every major component - deck, superstructure, substructure, or culvert - is rated 7 or higher on FHWA's 0-9 scale: no more than minor problems.

Component ratings


Structure	Steel stringer or multi-beam girder
Length	about 35 ft
Location	5.6 S 4.3 E Leadore
NBI structure number	000000000036165
Condition class	Good

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

Bridge	Built	Vehicles/day	Condition
US 93 over Salmon River;salmon Br.	1926	7,300	Poor
US 93 over Salmon River;carmen Br.	1970	2,100	Fair
US 93 over Carmen Creek	1931	2,100	Fair
US 93 over Tower Creek	1931	2,100	Fair
SH 28 over Lemhi River	2001	1,700	Good
SH 28 over Lemhi River	2001	1,700	Good