Blockstellen

Blockstellen are locations on a railway network from which a block system is operated. They control the block section of track between fixed boundaries, usually between two signal boxes or signaling points. The primary purpose is to ensure safe train movement by preventing more than one train from occupying the same block at the same time and by coordinating entry and exit permissions between neighboring sections.

A Blockstelle typically houses the equipment that governs signals and points for its block, as well as devices that detect whether the block is occupied. Occupancy information is exchanged with adjacent Blockstellen and with a central control center where applicable. The operator or the interlocking logic uses this information to authorize trains to enter a block and to set the appropriate signals and route.

Historically, Blockstellen began as mechanical or hand-operated signal boxes with lever frames. With electrification and the introduction of relay-based and later electronic interlocking, the functionality of Blockstellen expanded to include more complex logic and fast, remote communication. In modern networks, many Blockstellen are integrated into electronic or computer-based interlocking systems (ESTW) or are part of centralized traffic control, retaining their role as local control points for block boundaries.

Blockstellen are related to the concept of block sections (Blockabschnitte) and are distinct from central Stellwerke, though today many Blockstellen are embedded in larger interlocking installations. They remain a fundamental element in the safe and orderly sequencing of trains, especially on routes where centralized control is not present or where regional subsystems require local management of block boundaries.