Method for monitoring a railway system regarding the intrusion of persons, with a monitoring system comprising a plurality of sensors for detecting emissions from persons or from devices, such as noise, speech, gases, radiation and vibrations, and for emitting corresponding sensor signals, and at least one computer unit (11; 101) with a monitoring programme (19, 109) implemented for processing the sensor signals and for determining information about the persons, characterised in that a plurality of battery-powered monitoring modules (1, 1A, 1B) are arranged at a distance from one another within the railway system; - each comprising at least one sensor for detecting emissions and forming corresponding local sensor signals; - each comprising at least one computer module with a processor and a memory unit, in which a local monitoring program is implemented, by means of which the local sensor signals are processed to determine corresponding local information; - each comprising at least one communication unit by means of which the local information is transmitted directly or indirectly to a central computer; - having a housing in the shape of a system-typical element, such as the shape of a railroad ballast stone; and that sample signals or sample information or comparison patterns are stored in the memory unit of the computer modules of the monitoring modules (1, 1A, 1B), which represent events (E1, E2,..., En) typical of the intrusion of persons or typical of the railway system; that by means of the local monitoring programme for the local sensor signals in the computer modules, event patterns are determined and compared with stored comparison patterns to determine local information that is transmitted to the central computer; and that a central monitoring program is implemented in the central computer, which evaluates the local information output by the monitoring modules (1A, 1B) in order to determine events (E1; E2;...; En) individually or linked together as event sequences (E1 - E2 - E3,..., En), wherein the local monitoring programme of the monitoring modules (1A, 1B) has a speech recognition module, by means of which event patterns are evaluated with regard to the presence of speech or words. a plurality of sensors for detecting emissions from persons or from devices, such as noise, speech, gases, radiation and vibrations, and for emitting corresponding sensor signals, and at least one computer unit (11; 101) with a monitoring programme (19, 109) implemented for processing the sensor signals and for determining information about the persons, characterised in that a plurality of battery-powered monitoring modules (1, 1A, 1B) are arranged at a distance from one another within the railway system; - each comprising at least one sensor for detecting emissions and forming corresponding local sensor signals; - each comprising at least one computer module with a processor and a memory unit, in which a local monitoring program is implemented, by means of which the local sensor signals are processed to determine corresponding local information; - each comprising at least one communication unit by means of which the local information is transmitted directly or indirectly to a central computer; - having a housing in the shape of a system-typical element, such as the shape of a railroad ballast stone; and - each comprising at least one sensor for detecting emissions and forming corresponding local sensor signals; - each comprising at least one computer module with a processor and a memory unit, in which a local monitoring program is implemented, by means of which the local sensor signals are processed to determine corresponding local information; - each comprising at least one communication unit by means of which the local information is transmitted directly or indirectly to a central computer; - having a housing in the shape of a system-typical element, such as the shape of a railroad ballast stone; and that sample signals or sample information or comparison patterns are stored in the memory unit of the computer modules of the monitoring modules (1, 1A, 1B), which represent events (E1, E2,..., En) typical of the intrusion of persons or typical of the railway system; that by means of the local monitoring programme for the local sensor signals in the computer modules, event patterns are determined and compared with stored comparison patterns to determine local information that is transmitted to the central computer; and that a central monitoring program is implemented in the central computer, which evaluates the local information output by the monitoring modules (1A, 1B) in order to determine events (E1; E2;...; En) individually or linked together as event sequences (E1 - E2 - E3,..., En), wherein the local monitoring programme of the monitoring modules (1A, 1B) has a speech recognition module, by means of which event patterns are evaluated with regard to the presence of speech or words.