Train detection is fundamental to railway signaling and safety, traditionally relying on infrastructure-heavy systems such as track circuits and axle counters. While reliable, these methods involve significant maintenance and are often limited in remote areas. This paper provides a comprehensive review of emerging vibration-based sensing techniques, which utilize accelerometers and geophones to capture distinct vibration signals for determining train presence, speed, direction, and distance. The review evaluates vibration-based approaches by comparing them with other modalities, including vision-based, acoustic, and magnetic detection. Finally, the study identifies current research gaps and outlines future directions for smarter, non-intrusive rail monitoring systems.