Track
Diverging route track strength tests were a major element of the trials conducted on the continuous mainline rail turnout.
consisted of operating 142,000kg wagons at 64km/h over the turnout with approximately 30 million tonnes of passing traffic accumulated. Diverging operations consisted of spotting approximately 275 loaded and empty wagons in a 107m siding at speeds ranging from 3km/h to 16km/h. The tests showed the prototype turnout performed very well in most aspects. The dynamic forces for mainline moves were quite low, similar to what is measured on open track, while dynamic forces on diverging moves, as Table 1 shows, were acceptable. A comparison was also made with a nearby split switch
Route
Vertical switch facing, diverging Vertical switch trailing, diverging No 20 split switch facing, diverging
Speed (km/h)
~ 3.2 ~ 8.0 ~ 3.2
No 20 split switch trailing, diverging ~ 8.0
turnout. Even though the split switch turnout is larger (No 20 versus No 11), the lateral forces were comparable. Maximum vertical loads are somewhat higher for the vertical switch from ramping in the switch, where wheels are raised above the stock rails (see photo on page 42). Table 2 lists the measured maximum dynamic loads for mainline moves through the two turnouts with the data split between the switch and the frog on each turnout. Note that in each location the continuous rail turnout produced lower maximum lateral forces. There were also similar drops in average lateral forces. The changes in running
Maximum lateral
force (kips) 15 20 14 20
Maximum vertical
force (kips) 56 58 49 50
Table 1: comparison of measured wheel/rail forces in the prototype and conventional switches.
Test route
Speed (km/h)
Prototype switch (facing & trailing point) mainline 16.09 Prototype lift frog (facing & trailing point) mainline 16.09 No 20 split switch (facing & trailing point) mainline 16.09 No 20 RBM frog (facing & trailing point) mainline 16.09
Maximum Maximum lateral
force (kips) force (kips) 8.8 2.0
vertical 43
13.5 6.5
43 43 47
Table 2: comparison of measured wheel/rail forces for mainline moves in the prototype and conventional switch turnouts.
40
surface in the conventional switch and frog generate lateral forces above those seen in open track. Maximum vertical forces at higher speeds should be similar to open track with continuous welded rail. Previous tests of a lift frog by TTCI at Fast showed 95% vertical forces of 47 and 76 kips for lift and railbound manganese frogs respectively at 64km/h. Testing also analysed stock rail and switch points wear. The switch points, with their non-conformal shapes and short vertical ramps, wore at a much higher rate per million-tonne than the stock rails. Table 3 shows wear rates for each of the four running rails in the prototype switch, with the switch point wear rates two to three orders of magnitude higher. However, the initial wear in the first measurement interval of 0.11 million tonnes was about 50% of the total wear of the gauge side and
Component Average Maximum wear rate
wear rate
Gauge side switch point 4.2903
Matching stock rail
Matching stock rail
Field side switch point 14.503
0.0129
(cm2/MGT) (cm2/MGT) 29.355 0.0129 28.090
0.00645 0.01935
Table 3: comparison of wear on vertical switch points and stock rails.
IRJ May 2013
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