ATP: automatic train protection

What ATP is

ATP (automatic train protection) gives you a maximum speed code in the cab and emergency-brakes if you breach it. It does not replace signals: it reads them and cuts the code when the aspect is restrictive or red.

In MetroSim you see it on the ATP panel (H in the cab), on the speedometer (limit needle) and on COSMOS. Drive mode 1 is ATP; 2 is ATO; 3 is M+25.

The cab code

The code is the speed ATP allows right now. The red needle (or panel digits) follows that value. It does not jump: it ramps down or up so you can brake in time.

If a lower limit is ahead (curve, diverge, circuit), the code starts to anticipate it in the last metres: you will see the needle fall before you reach the exact point.

• Needle / digits = permitted code.
• Overspeed LED or yellow COSMOS icon: you are above the code.
• ATP alarm / red icon: the system has tripped; you must reset.

Line, curves and circuits

Each track section has a base code (circuit). Curves cut that value: in tight areas you will see low codes (20, 30, 45…) even if the line allows more.

On L11 sharp curves drop to about 35 km/h and the code leads by about 160 m so you arrive already braked. L2/L3 also have curve zones with their own caps (Paral·lel throat, Bac de Roda, La Pau…).

Diverging switch

If a switch is set to diverge (turnout position), ATP applies a lower code on that stretch. It is usually about 35 km/h, and the cut starts about 160 m before the switch so you can brake. On the straight (switch normal) that cut is not applied.

This applies on L2, L3 and L11. If the ATP needle drops without a sharp curve in sight, check the map or HUD: you may be routed through a diverge.

Signals: yellow and code 0

ATP looks at the signal ahead on your track and direction.

• Restrictive aspect (not green, not red): the code drops. Beyond ~120 m it usually caps you at 30 km/h; closer in, at 15 km/h.
• Red signal: when you get very close (the last metre or two before the mast) the code goes to 0. In the cab you will see 0 km/h.
• On code 0, if you take power (controller open), the ATP alarm trips at once. Do not try to “push” the red.

Overspeed and alarm

If you are more than ~1 km/h above the code, ATP counts a time margin (usually about 4 seconds). If you do not drop within that window, it trips: emergency brake, “EXCESO DE VELOCIDAD” or “ALARMA ATP” overlay, and the train stops.

If you slow in time, the counter resets and you can continue. On code 0 there is no that margin: opening the controller trips at once.

• Driver reset: R or the Reset button, same idea as train-stop.
• CCM reset: call the control centre; you will see “ATP rearmado”.

M+25 mode

Key 3 enters M+25: manual running capped at 25 km/h. In that mode ATP will not trip on line-code overspeed (it still caps you at 25). Use it only when required (shunting / CCM order), not as a trick to ignore a red.