Based on verification described in the FHWA Traffic Noise Model Technical Manual , the FHWA determined the model was valid and fully acceptable for use.
Additional validation is necessary to provide increased confidence in the model's results.
Field measurements made to support the model validation will be used to begin study of atmospheric effects on the propagation of highway traffic noise, effects which may possibly be included in the FHWA TNM in the future. We hope a continued State pooled-fund study will provide additional support for this. Version 1.1 will also correct some problems and inconveniences and include limited GUI enhancements. The model's initial phase validation work and software improvements described above must be completed prior to the final phase-in of the FHWA TNM .