Axle Counter
An axle counter is a train detection system that counts wheel axles entering and leaving a track section using sensors clamped to the rail. When the number of axles counted out equals the number counted in, the section is clear. It is the main alternative to track circuits in modern signaling.
How it works
Each detection point has a pair of electromagnetic wheel sensors so the system can tell the direction of travel. Pulses from the sensors are sent to an evaluation unit, usually in a trackside cabinet or equipment room, which keeps a running count for each section and reports clear or occupied to the interlocking.
Because the count is stored rather than measured live, a disturbance such as a power loss or a maintenance vehicle can leave a section wrongly showing occupied. Restoring it requires a reset procedure, performed by a signaller with specific safety rules, and modern systems support this remotely. Newer axle counters communicate with the interlocking over standard IP networks, for example through EULYNX object controllers.
Why it matters for security
The shift from wired relay interfaces to IP-based evaluation units turns axle counters into networked devices that can be reached from the signaling network. A manipulated count or a forced reset could clear a section that is actually occupied, and remote reset functions are a natural target for misuse.
Axle counters are also frequently deployed in large numbers across a network, so they contribute significantly to the size of the asset inventory that must be tracked, patched where possible and monitored for abnormal communication.
Related solution
Protecting interlocking systems at the core of rail safety
Monitoring networked train detection and reset traffic between the field and the interlocking.
See the solution →
