Noise Wall FAQs

In 1976, the U.S. Congress passed legislation requiring states to provide mitigation for highway noise, which is considered an environmental impact, as a part of all Type I Federal Aid projects at impacted locations where it is reasonable and feasible.

Projects considered Type I are the construction of a highway at a new location or the physical alteration of an existing highway that significantly changes either the horizontal or vertical alignment or increases the number of traffic through-lanes.

Any sensitive outdoor human use activity area that is predicted to have a design year traffic noise level of 67 dBA decibels weighted for human hearing) or greater is considered an impacted location.

Federal regulators chose 67 dBA as the impact threshold because research has shown that above this level conversation between two people standing three feet apart and speaking in a normal voice is impaired.

Computerized noise models are developed for all Type I projects to predict design-year traffic noise levels, typically 20 years in the future. All locations that are predicted to have impacts are then considered for noise mitigation where reasonable and feasible.

Reasonable refers to the maximum barrier square footage or cost per residence benefiting from the noise mitigation. Feasible refers to whether the barrier can provide a substantial reduction in noise and other constructability issues.

Noise walls are designed to provide a minimum of five decibels of reduction in average background traffic noise for the majority of first row of residences located directly behind the wall, with a seven-decibel reduction in at least one location. The design goal for a sound barrier is a 10-decibel reduction. The reasonableness criterion places a practical limitation on the height of any noise barrier.

Trees provide a visual shield and some psychological benefit, but are not as effective at reducing noise levels as a solid barrier. It would take at least 100 feet of dense vegetation to provide the same acoustical benefit as the smallest feasible noise wall. The amount of right away along the Eisenhower in Oak Park along the Eisenhower is too small to be bermed and trees planted.

This depends on the distance between the listener and the wall. For residences located directly behind the wall, the perceived noise level will be cut in half. The benefit decreases as a listener moves farther away from the wall and is negligible at distances greater than 500 feet.

Double pane windows, heavy draperies and sealing cracks can result in a noticeable reduction in traffic noise inside a home, while also reducing heating and cooling costs. Unfortunately, IDOT does not have a program to provide help property owners pay for such improvements.

Noise barriers materials can include earth, concrete, wood and masonry block. Earthen berms work the best and are the least expensive, but a lack of available right of way usually makes concrete walls the most practical solution.

The Village will work closely with the community to ensure that IDOT considers reasonable design requests as part of the project plans.

Many people have reported some success with a technique called noise masking. Noise masking typically involves using white noise, such as a fan or waterfall, to drown out the traffic noise and make it less noticeable. While this technique may be appealing for some individuals, it is not a practical mitigation tool on a community scale.

IDOT publishes a detailed Highway Traffic Noise Assessment Manual (link to PDF). Appendix B offers answers to some of the most frequently asked question in Illinois - click here just to view the appendix. IDOT also created a brief Q&A on the noise wall process - click here to view.

Information on the I-290 reconstruction project is posted on this website - just click here for the main information page. The web page provides links to a wide range of details along with official IDOT documents and presentations made at public meetings. IDOT also maintains a project website eisenhowerexpressway.com.