train fact, normally when trains go past a signal they automatically turn red via whats known as the replacement control, in Scotland all signals by default have a delayed replacement control so if the snow plough is attached to the front the driver never sees the signal go back to red in their face
![From Wikipedia:
The purpose of a system is what it does (POSIWID) is a heuristic in systems thinking coined by the British management consultant Stafford Beer,[1] who stated that there is "no point in claiming that the purpose of a system is to do what it constantly fails to do".[2] It is used in systems theory, and is generally invoked to counter the notion that the purpose of a system can or should be read from the intentions of those who design, operate, or promote it. When a system's side effects or unintended consequences reveal that its behaviour is poorly understood, then the POSIWID perspective can balance political understandings of system behaviour with a more straightforwardly descriptive view.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:xa4eltdd2z3scndtv4yvb65p/bafkreiem4i55e3gqp6endhcbz2voh2vgqd4y5xdo7bd5qgkrvnz745riby)