The bar is the gap between the two trains. The white tick is the safe distance: how far the rear
train needs to stop with normal braking at its current speed, plus a 200 m margin (about 750 m at 100 km/h,
5.2 km at 300 km/h; head-on, both trains' braking distances). A bar that stops short of the tick means the
trains are too close.
Critical closer than the rear train could stop, and still closing.
Warning too close now, or will be within a minute.
Watch will be within 3 minutes, or the data is uncertain.
Times assume both trains keep their current speed. Positions are Renfe's GPS, 15–60 s old, and there is no
signalling data, so this is a guide, not a safety system.