Abstract: A sensor module (100) for a pipeline vehicle (110) is disclosed. The sensor module (100) includes an outwardly biased sensor arm (120) pivotally connected at a hinge (129) mounted on the vehicle (110), whereby the angle between the sensor arm (120) and pipeline vehicle (110) is representative of a pipeline dimension. A magnet (240) and magnetic flux sensor (252) are mounted in the sensor module (100) to move relative to one another as the sensor arm (120) pivots relative to the vehicle (110). Measurement of change in magnetic flux can permit determination of the angle between the sensor arm and the vehicle. The sensor module (100) may be mounted on an upstanding flange (111) via a compliant (deformable) layer (202) which permits lateral deflection of the module (100) relative to the vehicle (110).