Comparison of post-construction barriers in TNM 2.5/3.x

In late 2024, a brand-new multi-lane bypass toll freeway with multiple barrier systems was completed and opened for public use. The original pre-construction sound study included pre-construction sound measurements and modeled predictions of the performance of the barrier system using the Federal Highway Administration's Traffic Noise Model (TNM) version 2.5. Following construction of the barrier system, post-construction sound measurements were conducted. These post-construction measurements were compared to modeled predictions for both the newly released TNM 3.x and the older TNM 2.5. This paper compares post-construction barrier results that were predicted using TNM 2.5 for the original study with post-construction barrier results using TNM 3.x and to the actual measurements conducted in the field. By comparing the multiple sets of both predicted and real-world measurement data, the authors hope to provide insight on the differences between the two versions of TNM and the real-world results from the application of the barrier system.