Interface - The Journal of Wheel/Rail Interaction

FRICTION MANAGEMENT

Optimizing Friction Management and Curve Elevation on Union Pacific (continued)

In addition to evaluating new technology, UP routinely evaluates existing products and technologies, as well. This helps measure maintenance quality, and illustrates the maintenance effort required to maximize the benefits of a given technology.

Proof of rail savings is another method that allows UP to quantify the benefits of friction management. UP is currently outfitting several locations with optimized GF and TOR applicators, and will monitor its curve rail program in order to quantify actual rail savings. Tangible savings of 10 miles of rail, for example, can be easier to understand and visualize than savings reported in reduced rail wear percentages. People can see and understand the impact of miles of rail more readily than the reduction from 1/32-inch to 1/64-inch of wear per year.

The final piece of the friction management puzzle is cross-functional financial participation. Many departments realize benefits from the friction management program. There are proven benefits to wheel life and fuel consumption, for example. If the departments that reap the benefits share the costs, it frees up money to expand proven programs and net more benefits all around.

Optimizing Curve Elevation
fig 3

UP is also making efforts to extend curve rail life through optimized curve elevation. Proper curve elevation can greatly improve the life of curve rail, and has the potential to synchronize replacement cycles by evenly distributing wear to the high and low rails. Figure 3 shows two high rail cross sections. The image on the left shows the result of poor elevation; the curve is under elevated for the traffic running on it. This results in much more gauge-face wear, and minimal vertical wear. The image on the right shows a curve that is properly elevated and wearing nearly equally on both planes. Each of these curves has met the wear criteria to be replaced, but the curve (on the right) with proper elevation has 47% more metal removed with no more risk, since the wear is on the rail head, rather than at the gauge face. Curve elevation has the same effect on the low rail, as well. If a curve is over elevated the low rail will wear much faster than it would if it was properly elevated. The potential for rolling contact fatigue is also much greater.

fig 4

UP is using geometry car data to identify and correct curve elevations. The geometry car currently takes rail profiles every 10 feet, but will soon be upgraded to collect profiles every 2 feet. The average of the worst 40 measurements is used as the wear baseline for a given curve. With this, we will be able to monitor high rail wear patterns and determine if wear is occurring at the proper rate. Curves that show abnormal wear patterns, as shown in Figure 4, are flagged and investigated to determine the reason for that wear.

If the curve is not wearing properly and it is not set to the standard elevation it will be flagged for surfacing, to be brought into compliance. The other potential problem is not as simple to fix or identify. If the curve shows abnormal wear but is already at the standard elevation, there may be location-specific operating conditions that require a different elevation. An example of this may be a curve going into a terminal or staging location on which trains are never making speed. Reducing elevation would correct the problem, in this case. Another example may be a situation where loads running up hill are not making speed, while unloaded cars are easily making speed down hill. In each of these cases, the location must be evaluated to determine the proper elevation for that curve.

As UP moves forward with this project, it will flag curves that are outside the expected wear line by 25% or more. UP will schedule surfacing if the elevation is not set to the UP standard, or will further study it if it is. These curves will be monitored to understand the life extension benefit and to calculate the ROI.

UP is committed to fully understanding the costs/benefits of existing programs and technologies that can be used to either prove or disprove current spending levels. It may become evident that a significant increase in one area (such as rail grinding) could reduce costs in another (such as curve replacement). For every mile of curve rail that we save, we can add 1.25 miles of new rail. If we can maximize the life of rail assets, we can invest in other aspects of maintenance and make the railroad a safer place.

References
1) Roney, M., Reducing the Stress State on CP's Western Corridor Operations, Wheel/Rail Interaction 2009, Chicago, IL.

Mike Gilliam is Director of Track Maintenance; Russell Rohlfs is Director of Rail Maintenance, Union Pacific.

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