In the face of growing demand, the way rail infrastructure is used must change. Although it is obvious that the infrastructure is underutilized, conventional safety systems and the lack of direct communication between trains are the main reasons for the limited use of railroad tracks. One of the applications that has the potential to enable a significantly more efficient use of railroad infrastructure is Automatic Train Coupling (ATC). ATC is a method for automatically coupling and decoupling train wagons. This can be done while one wagon is standing still or while both wagons are in motion. ATC has the potential to increase track utilization for passenger and cargo trains by allowing easy physical coupling of wagons when they occupy the same track block and decoupling when they otherwise do not. The aim of this work is to address the theoretical and practical aspects of the realization of ATC. A wireless Train-to-Train (T2T) communication system capable of accurate ranging is required for the realization of ATC. To this end, standardized and non-standardized communication systems are analyzed and a communication system is recommended on the basis of the investigations. To evaluate the communication and ranging performance of the proposed communication system in realistic railroad environments, a measurement campaign was conducted with two train wagons. The measurement data was used to derive a channel model and thereby evaluate the performance of the communication system. Results from modelling ATC systems and their interactions show that using the proposed mm-Wave communication system and the proposed ranging estimation method allow a guaranteed safety integrity level SIL-4 throughout the ATC maneuver.