A device for monitoring the transit of a user or of a land vehicle through a passage, the device being installable near the passage with a set orientation and having a set cover angle, the device comprising: - a receiver-transmitter of short-range radio signals configured to: • transmit data indicative of an unique recognition code of the passage (ID_2); • receive data indicative of a confirmation of receipt of an unique recognition code of a user (ID_1) and indicative of said unique recognition code of the user (ID_1) being present inside the set cover angle; - a processing unit configured to: a) receive a first presence detecting signal having a value that is indicative of the presence of the user and of the vehicle inside the set cover angle; b) calculate, at predetermined time intervals (ti), the distance (di) and the angle (αi) with respect to a fixed directrix of said set orientation of the device; c) determine a trajectory of the user or vehicle approaching the passage on the basis of a time sequence of calculated distances (di) and angles (αi); d) if said trajectory is within an activation area of the passage and approaches the passage, generate a command signal to open the passage and enable the user or the land vehicle to pass through. - a receiver-transmitter of short-range radio signals configured to: • transmit data indicative of an unique recognition code of the passage (ID_2); • receive data indicative of a confirmation of receipt of an unique recognition code of a user (ID_1) and indicative of said unique recognition code of the user (ID_1) being present inside the set cover angle; • transmit data indicative of an unique recognition code of the passage (ID_2); • receive data indicative of a confirmation of receipt of an unique recognition code of a user (ID_1) and indicative of said unique recognition code of the user (ID_1) being present inside the set cover angle; - a processing unit configured to: a) receive a first presence detecting signal having a value that is indicative of the presence of the user and of the vehicle inside the set cover angle; b) calculate, at predetermined time intervals (ti), the distance (di) and the angle (αi) with respect to a fixed directrix of said set orientation of the device; c) determine a trajectory of the user or vehicle approaching the passage on the basis of a time sequence of calculated distances (di) and angles (αi); d) if said trajectory is within an activation area of the passage and approaches the passage, generate a command signal to open the passage and enable the user or the land vehicle to pass through. a) receive a first presence detecting signal having a value that is indicative of the presence of the user and of the vehicle inside the set cover angle; b) calculate, at predetermined time intervals (ti), the distance (di) and the angle (αi) with respect to a fixed directrix of said set orientation of the device; c) determine a trajectory of the user or vehicle approaching the passage on the basis of a time sequence of calculated distances (di) and angles (αi); d) if said trajectory is within an activation area of the passage and approaches the passage, generate a command signal to open the passage and enable the user or the land vehicle to pass through.