Essentials of MSP
MSP essentially consists of taking accurate measurements of track defects, particularly of any existing unevenness and voids, caused in the course of service and attending to the same by placing a measured quantity of small-sized stone chips under the sleeper to bring the track levels to their predetermined state. The compaction of these stone chips occurs as a consequence of the passage of traffic. The extent to which the track is required to be lifted is calculated by measuring the longitudinal unevenness in the track once the cross levels and the voids under the sleepers have been corrected. The longitudinal levels are measured with the help of two optical instruments-the viseur and the mire-while the voids under the sleeper bed are assessed by a ball-ended rod called canne-a-boule and checked with the help of a mechanical device called the dansometer. The track is lifted by 40 mm by means of special types of non-infringing jacks, and a measured quantity of stone chips is then placed in the sleeper bed with the help of a particular type of packing shovel. The jacks are then tripped off and the alignment is finally corrected.