The Federal Aviation Administration (FAA) used the Integrated Noise Model (INM), Version 6.1, to support the aircraft noise assessments presented in Chapters 4 and 5 and Appendix F of the O’Hare Modernization Draft Environmental Impact Statement (DEIS).

The INM is a computer program used to evaluate the noise exposure effects associated with aircraft operations in an airport environs. Based on a series of data inputs the model produces noise exposure contours which are computer generated lines connecting points of equal levels of noise resulting from aircraft operations. The primary inputs to the model include runway location and orientation, annual average day operations by aircraft type and time of day, runway use and flight paths.

Using the INM, noise exposure contours were prepared for each alternative in accordance with FAA Order 1051.1E, Polices and Procedures for Considering Environmental Impacts and FAA order 5050.4A, Airport Environmental Handbook. A grid point analysis was also conducted for each alternative using the INM. Grid points show the changes in noise levels over specific locations and are helpful in determining where significant noise changes may occur.

The link below labeled Noise Modeling Background connects to Appendix F of the DEIS. Section F.2 provides a description of the methodology that was followed in developing INM input data for the 2002 Baseline Case, the Future No Action Alternatives and the Future Build Alternatives. This section also includes a summary of the noise model input data for each alternative.

The remaining links connect to the INM input and output file set for each respective alternative.

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