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🚦 Automatic Block on Double Track (BAD): Railway signaling system where each track is used exclusively in one direction. For example, from "A" to "B" in one direction and from "D" to "E" in the other. Only track locking/unlocking is allowed, with no possibility of bi-directional use.
🛤️ Track Circuit: Each section into which the railway track is divided. Each section has a signal (traffic light) indicating whether it is free or occupied. It detects train presence and ensures safety between trains.
🔀 Switch (or turnout): Mechanism allowing trains to change from one track to another. It can be in a straight position (continues on the same track) or diverging (toward another track). Its configuration affects the signal the driver sees.
| Track Circuit Status | Disc Color | Observations |
|---|---|---|
| The circuit is occupied (blocked by a train) | 🔴 Red | Indicates the train must not proceed |
| Circuit after a switch that is diverging | 🔴 Red | The turnout is not in the nominal travel direction; cannot continue straight |
| Circuit before an occupied one | 🟠 Amber | Caution: train ahead (red block) or end of track |
| Circuit with a diverging switch | 🟠 Amber | Indicates nearby turnout diverges from the nominal direction |
| Circuit with a straight switch | 🟢 Green | Clear straight track in nominal direction |
| Free circuit (unlocked) | 🟢 Green | Track is free |
| Circuit after a straight switch | 🟢 Green | Continues straight, track free in nominal direction |
| Route signal at a switch |
|
Indicates direction of the turnout |
On platform 2 at El Prat de Llobregat there is a train stopped indicated by a red track circuit.
On track 1 A a train is entering, meaning it has already blocked the first track circuit (red). This train needs a route to reach and stop at the last track circuit on track 3 before the buffer stop C.
➡️ Indicate the disc colors on track 2 and track 1 and establish the complete route from the entry on track 1 to the final stop on track 3, modifying signals as needed: blocking, unlocking, and turnout indications.
Once all signals are correctly set and the route is defined:
Good luck! 🚦
Additional clues:
10 🟢, 3 🟠, 3 🔴
2 🔴 signals on Track 1
You will find a small collection of videos of the station and old railway rolling stock at the following link:
🎥Modification history
| Date | Time | Description |
|---|---|---|
| 29/07/2025 | 02:45 | Creation |
| 18/08/2025 | 23:30 | Additional clue |
| 18/08/2025 | 23:35 | Correction of additional clue |
| 20/08/2025 | 21:53 | Clarifications and clue extension |