Track final positioning with the PALAS system

One of the RSRS activities in the use of advanced infrastructure technologies is implementation of projects aimed to improve the state of track infrastructure by putting the railway tracks in the optimal final position.
To achieve this goal, we apply the Swiss railway track positioning technology called PALAS, which allows us to keep the original track geometry when building and maintaining railway tracks.
The system provides absolute accuracy of the tamping machine operations enabling to automate the track final positioning process and to get a tangible improvement in passenger comfort while increasing the train running velocities.

The PALAS technology is patented by J. Müller AG. The PALAS system is a fully automatic measuring and guiding system designed to continuously position the track into the final position. The PALAS system recovers the absolute rail track geometry on the plain tracks and turnouts using triangulation and absolute measuring systems.

Setting the track into final position allows to reduce the rail track life-cycle cost and turn a trip into a more comfortable passenger experience due to better running smoothness and diminishing unbalanced accelerations on speed and high-speed routes. Absolute accuracy, high work pace of the entire complex and significant cost savings are the main advantages of the method.

Operating principle

Operating principle The track alignment operations involve a tamping machine equipped with the PALAS absolute positioning system. The system consists of a hardware and software complex installed in the track machine cabin, and a hydraulic and pneumatic trolley control system. The laser systems determining the track position in three planes and a gyroscope are mounted on the trolley. The gyroscope and other special equipment determine the position of the machine with its reference to the high-precision coordinate network (VKS).

Before the work begins the operator lowers the PALAS trolley to the operational position, turns on the computer and starts the system, which followed by the system determining its current spatial position with reference to the points of high-precision coordinate network. MEFISTO trolley is used for a more precise track positioning. A railroad worker positions the trolley by a laser beam pointed at a reference point on a catenary mast. The obtained track position coordinates are transmitted through a radio channel to the onboard PALAS complex. The tamping machine operator inputs the tolerances and the data into the computer. The computer compares the data with the design positions and determines the track shifting values. The machine is ready to use. Prior to the start of work, the mirror reflectors are installed on the catenary masts. Using the reflectors, the PALAS system continuously, automatically and with extreme accuracy measures the track positions in 3 planes, calculates the track shiftings and transfers data to the tamping machine computer that performs alignment operations.

The machine can shift the track up to 100 mm horizontally and up to 70 mm vertically in a single run. If further alignment is required, the machine goes back and makes another run based on the precise tying to the reference points with the help of laser. After the work completion, the mirrors are removed, and the machine goes to the next rail haul.

Depending on the railway track deterioration, the machine with the PALAS system can be brought back to the repair area to align the track based on the existing design and the current track position, with no need for preliminary preparation.

The track final positioning tolerance does not exceed 2 mm. The average complex speed is 1.5 km. per hour.
Infrastructure downtime reduces by 30 %.

 PALAS system

Wagon W

Back to top