Interface - The Journal of Wheel/Rail Interaction

RAIL GRINDING ON UP

A Measured Approach to Improvements in Rail Grinding (Continued)

Improving Grind Quality
UP is also working with its service providers to move toward computer-generated pattern selection. Most grinders have the ability to use rail profile data to select the best templates to re-shape the rail profile. This could increase grinding speeds and reduce the number of passes required. The cost associated with auto generation of the patterns must be weighed against the productivity gains to determine the potential for productivity increases.

Also tied to grinding speed is the quality of the grind. UP has been working over the past few years to obtain a quality index behind the grinder. This index will allow UP personnel to understand the impact of increasing speeds with certain patterns, for example, and provide a quality audit tool to ensure that the railroad is getting what it pays for. A quality index will also provide a better understanding of the effect of grinding over the life of the rail.

With a quality index, UP will be able to monitor rail on a subdivision or specific segment of track to see if the average profile is getting better or worse. It will then be able to cross reference defects or service failures with rail profile quality. If the data shows that the rail defect rate is higher in areas with poor profile conditions, it can be used to justify increasing the grinding budget, or moving funds earmarked for rail replacement to the grinding program.

UP has established test locations to monitor various levels of grinding. UP is skipping selected curves and tangent sections during their regular grinding cycle to see how fast RCF develops, and to dial in the optimum cycles. Figure 3a shows the amount of spalling that develops at approximately 60-mgt grinding cycles. UP has since cleaned up this curve and kept if free of spalls with 35- to 40-mgt grinding cycles (Figure 3b).

UP is collaborating with the Transportation Technology Center Inc. (TTCI) at a western mega site to compare the effects of preventive grinding to the use of top-of-rail (TOR) friction management on the development of RCF on low-degree curves in heavy-tonnage territory. UP expects to be able to compare the cost of grinding versus friction management and their effects on rail life.

Switch Grinding

After years without a switch grinding program, UP began working a switch grinder again, this year. The major obstacle in the past was obtaining track time. Switch grinding is an inefficient process; much of the track time is consumed traveling between switches, or waiting to grind the turnout side of a switch. Granting permission to grind the turnout side is what gives the dispatch center the most trouble. On double track, which is where switch grinders are typically operated, dispatchers do a good job of providing time on one track. But access to both tracks is needed to fully grind the switch. Granting time on both tracks is hard for dispatchers to do, so the switch grinding program suffers.

Figure 4 shows a crossover on the heavy-tonnage Kearney Sub, the dividing point at which loaded coal goes to either Kansas City or Chicago. Because of the volume and tonnage, these turnouts require a lot of maintenance, from hand grinding to surfacing. If UP can quantify the savings that switch grinding can provide (in all of the maintenance categories), it will be able to obtain additional maintenance funding. Figure 5 shows some of the conditions that could have been prevented with a switch grinding program. Instead, this defect will require replacement of a movable point frog. This comes with very high material and labor costs, not to mention the network impact of having the crossover down while the changeout is done.

Among the areas that UP is exploring is non-destructive measurement of the depth of cracks on the rail surface. An accurate measurement of crack depth would help grinding supervisors to minimize metal removal and maximize grinding speed. UP is also looking for a way to quantify rail life extension due to grinding. UP currently correlates the number of pass miles ground to the number of detail fractures per mile. As Figure 6 indicates, when the number of pass miles (shown in green) increases, the number of defects (shown in orange) decreases.

Through close monitoring, UP hopes to further extend the life of the rail on the system. Analysis may show that a significant increase in grinding could reduce the need to replace rail in curves, which could enable UP to increase rail programs. For every mile of curve rail that is saved, 1.25 miles of new rail can be added. The ability to lay rail out-of-face, rather than skipping around to lay various curves, can significantly improve the efficiency of maintenance.

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

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