In an extensive third phase of a Federal Railroad Administration-funded research project running from August 2020 through July 2022, a team at the Advanced Telecommunications Engineering Laboratory at the University of Nebraska-Lincoln designed, developed, and evaluated wireless communications architectures for rail services in North America, with a focus on high-speed rail services. During this phase, the team focused on mitigating a significant challenge, not only in the rail industry but in fact across all sectors: radio frequency (RF) spectrum scarcity. RF spectrum resources are a necessity for any wireless solution, and with the rapid proliferation of wireless services and applications in all aspects of daily life and society, RF resources are becoming overused and expensive to license. Therefore, the team studied RF spectrum already owned by the rail industry, but that may be abandoned, underused, or used only for legacy applications. Such bands are ideal candidates for modernization and re-use.