Method and device for compressing a track ballast bed

The invention relates to a method for compressing a track ballast bed (5) by means of a tamping assembly (7), comprising two opposing tamping tools (8), which, during a tamping process (9), are lowered into the track ballast bed (5) with the application of vibrations (13) and are moved towards one another with a lateral movement (18). In addition, at least for a tamping tool (8) during a vibration cycle (29), a course (28) of a force (21) acting on the tamping tool (8) over a path (23, 27) travelled by the tamping tool (8) is detected by means of sensors (20, 22, 24) arranged on the tamping assembly (7), wherein at least one characteristic variable (31-40) is derived from this, by means of which an evaluation of the tamping process (9) and/or of a quality of the track ballast bed (5) occurs. In this way, the tamping assembly (7) is used as a measuring device during an operative application.