Vastbloksignalen

Vastbloksignalen, often translated as "fixed block signals," refers to a railway signaling system where track is divided into fixed sections called blocks. Each block is protected by a signal. A train can only enter a block if the signal governing that block is showing a permissive aspect, indicating the block is clear. This system is designed to maintain a safe distance between following trains, preventing collisions.

The principle of operation is straightforward. When a train passes a signal, that signal is typically set to a stop aspect (red), and the signal protecting the block *ahead* of it is cleared. As the train clears the block it entered, the signal behind it is then allowed to change, potentially to a permissive aspect, allowing the next train to proceed. The size of the blocks is determined by factors such as train speed, braking capabilities, and local line characteristics.

Fixed block signaling systems have been a cornerstone of railway safety for many years and are widely implemented across the globe. While effective, they can sometimes limit line capacity compared to more modern moving block systems, which allow trains to follow each other more closely based on real-time positioning rather than fixed track segments. Despite this, vastbloksignalen remains a reliable and foundational element of railway operations.