Il 173 over Des Plaines River

Lake County, Illinois · rated Good in the 2025 National Bridge Inventory

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

• Il 173 over Des Plaines River in Lake County, Illinois, is rated in good condition in the 2025 National Bridge Inventory (as of August 20, 2026).
• Its lowest-rated component is the deck, rated 7 (good condition) on the 0-9 scale.
• It was built in 1929 and reconstructed in 2011, making it 96 years old at the 2025 inventory.
• It carries about 11,200 vehicles a day (traffic count year 2023).
• Its listed owner is the state highway agency.
• It is one of 76 of the 250 inventoried bridges in Lake County rated good (30.4%); 24 (9.6%) 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.

View this bridge on a map → (42.46536, -87.94288)

Component ratings

Bridge details

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

Busiest bridges in Lake County

All bridges nearby: Lake County, IL bridge conditions · every bridge in Lake County · Illinois bridges.

Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.