The Z21 part of the Kradex system is a digital railway signalling solution designed to enable modernised rail operations and improved safety performance. It is an advanced interlocking solution designed to provide efficient, safe and reliable operation for railway signalling applications. The Z21 part of the system utilizes digital technology, including sensors, cameras, computers, and communications links to track the motion of trains and automatically control safety operations. It offers a range of features, including monitoring of track sections and points, operating of level crossings, status display for signal boxes, and control of speed limits. It also provides interfaces for integrating with other train control systems, enabling complete automation of the railway network.