Illinois Department of Transportation, Erica Borggren, Acting Secretary
Patrick J. Quinn, Governor
Traveling PublicMapsProjectsRoad ClosuresNewsDoing BusinessLetting & BiddingCareers@IDOTGeneral Info

Part I Noise Fundamentals

Part II Noise Analysis

Part III Noise Abatement

Frequently Asked Questions

Glossary and Acronyms


Typical Posted Speeds in Illinois


  • Rural Interstates
    • 65 mph (cars)
    • 55 mph (trucks)


  • Urban Interstates
    • 55 mph


Traffic speed is input into the model as the average vehicle speed.

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