In view of the sign, what separation must you maintain from the vehicle travelling ahead?

The sign in the question prohibits travelling without maintaining a separation from the preceding vehicle equal to or greater than that indicated on the sign, except when overtaking. If it appears without the indication in metres, it serves as a general reminder that the safety distance between vehicles must be kept. The safety distance is the space that allows you to stop, in the event of sudden braking, without colliding with the vehicle ahead, taking into account speed and the conditions of grip and braking. Furthermore, if you do not intend to overtake, you must leave enough space for the vehicle behind you to overtake. Vehicles with a GVW of more than 3,500 kg and vehicles and vehicle combinations of more than 10 metres must maintain a minimum separation of 50 m. In tunnels and underpasses, a safety distance of at least 100 metres or 4 seconds must be maintained from the preceding vehicle. Vehicles with a GVW of more than 3,500 kg must maintain 150 metres or 6 seconds.