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Royston over Big Thornapple Drain

Eaton County, Michigan · rated Fair in the 2025 National Bridge Inventory

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

Royston over Big Thornapple Drain in Eaton County, Michigan, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the deck, rated 6 (satisfactory condition) on the 0-9 scale.
It was built in 1952, making it 73 years old at the 2025 inventory.
It carries about 78 vehicles a day (traffic count year 2011).
Its listed owner is the county highway agency.
It is one of 128 of the 202 inventoried bridges in Eaton County rated fair (63.4%); 11 (5.4%) 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


Structure	Prestressed concrete multiple box beam
Length	about 42 ft
Location	2 Mi SE Potterville
NBI structure number	000000000002376
Condition class	Fair

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

Bridge	Built	Vehicles/day	Condition
I-96 WB over Grand Riv & Billwood Hwy	2023	47,900	Good
I-96 EB over M-43	1962	31,250	Fair
I-96 WB over M-43	1962	31,250	Fair
Otto Road over I-69	1989	27,800	Fair
I-96 EB over Grand River	1962	27,100	Fair
I-96 WB over Grand River	1962	27,100	Fair