A system for travelling through a pipeline in a driving direction comprising a guide device, wherein the guide device, comprises: a carriage defining a longitudinal extent between a front end of the carriage and a rear end of the carriage; at least three surface engagement members (21.i), mounted to the carriage; and a detection unit, arranged on the carriage,; wherein each of the at least three surface engagement members (21.i) are arranged for being independently movable between a first retracted radial position wherein the engagement member has a first radial distance to an axial axis of the guiding device, and an extended radial position wherein the engagement member has a maximal radial distance to the axial axis of the guiding device and wherein the first radial distance is smaller than the maximal radial distance and may be a first minimal distance, wherein the device further comprises a first biasing system (31.i) for biasing each of the at least three surface engagement members, from the first retracted radial position, towards the extended radial position, characterized in that the at least three surface engagement members (21.i) are arranged for supporting and guiding the carriage along an inner surface of a pipeline in at least the driving direction which extends from the rear end towards the front end of the guide device, wherein the detection unit is arranged for detecting, and sending a detection signal, when at least one member of the at least three surface engagement members moves in the direction of and along a path extending from the first retracted radial position to the extended radial position into, or beyond, a detection position which lays between the first retracted radial position and the extended radial position wherein the system is provided with a traction unit for driving the guide device in at least the driving direction, wherein preferably the traction unit is arranged for receiving the detection signal and wherein the system is arranged to stop and/or reverse the traction unit if the detection unit, in use, detects that at least one member of the at least three surface engagement members moves in the direction of and along the path extending from the first retracted radial position towards the extended radial position into, or beyond, the detection radial position. a carriage defining a longitudinal extent between a front end of the carriage and a rear end of the carriage; at least three surface engagement members (21.i), mounted to the carriage; and a detection unit, arranged on the carriage,; wherein each of the at least three surface engagement members (21.i) are arranged for being independently movable between a first retracted radial position wherein the engagement member has a first radial distance to an axial axis of the guiding device, and an extended radial position wherein the engagement member has a maximal radial distance to the axial axis of the guiding device and wherein the first radial distance is smaller than the maximal radial distance and may be a first minimal distance, wherein the device further comprises a first biasing system (31.i) for biasing each of the at least three surface engagement members, from the first retracted radial position, towards the extended radial position, characterized in that the at least three surface engagement members (21.i) are arranged for supporting and guiding the carriage along an inner surface of a pipeline in at least the driving direction which extends from the rear end towards the front end of the guide device, wherein the detection unit is arranged for detecting, and sending a detection signal, when at least one member of the at least three surface engagement members moves in the direction of and along a path extending from the first retracted radial position to the extended radial position into, or beyond, a detection position which lays between the first retracted radial position and the extended radial position wherein the system is provided with a traction unit for driving the guide device in at least the driving direction, wherein preferably the traction unit is arranged for receiving the detection signal and wherein the system is arranged to stop and/or reverse the traction unit if the detection unit, in use, detects that at least one member of the at least three surface engagement members moves in the direction of and along the path extending from the first retracted radial position towards the extended radial position into, or beyond, the detection radial position.