Abstract: A railway track renewal or construction car for use in a track renewal or construction train, which car is in the form of a straight beam resting on its ends on two rail engaging bogies, the front of which is adapted to roll on the old track to be renewed and the rear of which runs on the track which just has been renewed. Between the bogies, there is provided a device for removing the rails of the old track, means for discarding the old ties, a means for regulating the ballast, a means for laying new ties and a means for closing the new rails previously laid on either side of the track. In order to permit such a car to operate on a cleared right-of-way where no previous track exists, the car is provided with a telescopic undercarriage which can be lowered onto the ballast of the right of way replacing the front bogie as a front support for the car. The undercarriage is provided with a suitable rolling device such as an endless track.

Abstract: The invention is a process and a device for measuring and registering the geometric state of a track in the course of alignment of the track with an aligning machine. The distance between a point on the already aligned track and a straight line defined by two points, one of which is on the already aligned track and one of which is on the part of the track to be aligned, is measured, and the value is registered after each alignment operation.

Abstract: A process and a machine for tamping railway tracks so as to obtain the same degree of compactness of the ballast under all the sleepers of the track tamped by the machine. A movable tamping machine with vibratory tamping tools tamps the ballast between and under the sleepers. A pick-up device measures the amplitude of vibrations retransmitted by the ballast across the sleepers and the rails to a part of the machine which is maintained in non-elastic connection with one rail of the track. The pick-up is rigidly fixed to this part of the machine. A computer is provided to emit a control signal to a control device for stopping the compacting operation of the tools. This signal is emitted when a predetermined value (K) of increase in amplitude of the vibrations measured by the pick-up device is reached, this value being characteristic of the approach of the maximal degree of compactness of the treated ballast.