Model test results for different sleeper spacings - 5mm and 2mm crib ballast 20 simple and 20 uplift cycles.Click for better view of graph

Model tests and box tests for 50mm crib ballast - 20 simple and 20 lift cycles Click for better view of graph

Model tests, box tests and full scale tests for 20 simple and 20 lift cycles Click for better view of graph

Observations

• The smaller crib ballast fills in the void below the sleepers during the uplift cycles for all the tests.
• The void size is reduced to less than the void size minus the average particle size of the crib ballast. Thus for a void size of 25mm with average particle size of crib ballast 15mm (stone blowing stone particle size range) the void size after 20 uplift cycles is reduced to 10mm.

Thus the model tests and the full scale tests have shown that the system is capable of partially filling the voids under the sleepers and reducing sleeper hammer. The deterioration of vertical alignment of track is corrected by the proposed system while there is rapid deterioration of vertical alignment of track in standard ballast.The particle size of crib ballast influences the final sleeper level and residual sleeper hammer.

To correct the loss of vertical track geometry (slack) it is proposed to use the surface vibrating equipment (dynamic track stabilizer) to vibrate the crib ballast into the space below the sleepers after jacking the track up to the required level.

Live track trails

It is proposed to go out on live track trials in the near future. For the first time attempt will be made to record displacement of track under train loads by using digital video photography. Watch this space for further details.

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