Track
90% for the field side points. The wear rate is expected to continue to decrease as the points reach shapes that are conformal to wheels. Figures 3 and 4 show the switch point wear versus location for three accumulated tonnages. Note the similarities and differences in wear of the two switch points. In both cases, the locations of highest wear rate are at the point ends where the wheel impacts the end of the point as it rolls in a facing point move. Also noteworthy is somewhat higher wear at the top of the point ramps. The effect of running surface profile may explain the higher wear rate (reported as cross section area loss) on the field side point. Both points started with the same rectangular shape with the running surface available to the wheel on the field side point much smaller and perhaps less conformal. In addition, the field side point is a composite structure consisting of three pieces. Shifting of the pieces relative to each other may cause some of the wear reported for this switch point. Since completing the tests, several design improvements have been made by BNSF, Progress Rail Services, and TTCI ahead of introduction into
revenue service, including: lateral stiffening of the field side
point to prevent gauge widening reconfiguration of the switch heels to
reduce switch throw effort, and reconfiguration of the point guard to increase the available contact area with the wheel and to simplify construction. A continuous rail turnout incorporating these modifications is now in revenue service on a BNSF line
20 0
-20 -40 -60 -80 -100 -120 -140 -160 -180
0.00
0.08
0.15
0.30
0.61
0.91
1.22 Distance from point of switch (metres)
1.52
1.83
Figure 3: gauge side switch point wear vs distance.
20 0
-20 -40 -60 -80 -100 -120 -140 -160 -180
0.00
0.08
0.15
0.30
0.61
0.91
1.22 Distance from point of switch (metres)
1.52
1.83
Figure 4: field side switch point wear vs distance.
in Texas. While the mainline carries 60 million tonnes of traffic per year, the turnout is only used once or twice a
week by a company shipping industrial aggregate, and is therefore an ideal example installation for the new turnout. Since installation in March, the turnout has performed well, with analysis continuing.
The next step for the continuous turnout concept is to receive approval from the American Standards Commission at its meeting with the track structure engineers this month. If this is secured we expect significant interest in the concept from other railways in North America and will work with the supply industry to enable them to develop concepts for market. While we worked with Progress Rail Services on the system for BNSF, VAE has also worked on a concept with a view to working with Union Pacific, but has not yet developed a prototype. IRJ
Ramping in prototype switch points. 42
TTCI employees Mr Muhammad Akhtar, Mr Joseph LoPresti, and Ms Beatrice Rael contributed to this article.
IRJ May 2013
Wear (mm²)
Wear (mm²)
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60