Interface - The Journal of Wheel/Rail Interaction

RAIL GRINDING ON UP

A Measured Approach to Improvements in Rail Grinding
By Mike Gilliam and Russell Rohlfs • July 2010

The Union Pacific Railway has 30,000 mainline miles of track over 23, primarily, western states. It has more than 6,500 miles of curves, which require significant maintenance efforts, such as rail grinding and lubrication. It’s a challenge to manage the rail assets, as rail weights have varying replacement criteria, and various metallurgies require different grinding frequencies. This challenge led to re-organization a couple years ago, and creation of the Director of Rail Management position.

The Director of Rail Management is charged with eliminating service failures and maximizing the rail asset. Previously, many of the functions in the Maintenance group were not centralized, but controlled by each operating region or service unit. This resulted in a multitude of different standards, practices and operating procedures. UP has since centralized control in an effort to maximize the benefit for the money spent on grinding, lubrication and other programs. While rail grinding or lubrication may have a very attractive ROI on their own, they are battling for funding with tie, rail, turnout, yard rehab and surfacing projects, to name a few. Each expenditure must be able to demonstrate an extension in asset life, or increase in the level of service.

Based on the preventive grinding cycle frequencies currently recommended by AREMA, UP would need to grind approximately 19,000 pass miles per year. This assumes that there is new rail in all of the locations to be addressed by a preventive grinding cycle. This is not the case on UP. Many curves require multiple cycles with multiple passes in order to get the rail into the desired profile condition. In order to do this, UP estimates the annual requirement is closer to 23,000 pass miles. Based on the number of available grinding hours per day (3.04 hours per day in 2009), UP would need to work 4.25 grinders the entire year; it’s currently working only four. How can UP bridge this gap?

With costs increasing faster than budgets, there are three likely options. UP can:
• Increase grinding time, which requires an internal balancing act based on the need to move freight to pay for the grinders and maintain the fixed assets.
• Become more efficient with the available grinding time.
• Increase the grinding budget (which should be pursued only after the first two options have been exercised).

Scheduling grinding work represents an ongoing challenge at UP. Maintaining tonnage-based cycles is not always possible. Because of fire danger in the western U.S., some territories that should be ground three or four times per year can be ground only once per year. This requires multiple passes on curves, which requires excessive metal removal and results in low productivity rates — neither of which is cost effective.

Another consideration is that some territories have a mix of Head-Hardened (HH) and Standard Strength (SS) rail. Because of the logistics, UP has to choose to grind at either the HH frequency or the SS frequency. This leads to either over grinding or making more passes than otherwise necessary — both of which reduce the productivity and cost effectiveness of the grinding machine. Some of this can be remediated with good record keeping of the rail type, which enables the grinder to increase the grinding speed and reduce the metal-removal rates on the HH rail, and to reduce the grinding speed and increase the metal remove rates on the SS rail. This procedure requires thorough pre-inspections and good communication with the machine operators.

Improving Efficiency
The need to increase grinding time results in an internal negotiation between those who need the track time and those who grant the track authority. This is an on-going battle that every M/W discipline faces. UP has worked to increase awareness of the importance of grinding to operations and the dispatching center management. We have set goals for grinding permit time, and discuss them daily on system conference calls in much the same way that we manage track curfews for large renewal gangs. This creates accountability for maximizing on-track windows. We have also educated dispatchers on how the grinder works, what it does, where it can clear and the costs associated with not working the equipment. Helping them understand the value from a defect-prevention standpoint helps them understand how grinding can reduce the need for slow orders or track time to repair a defect or service failure later.

Once a track window has been granted, the UP grinding team and the service provider have to perform as much work as possible within the available track time. We do this in a few different ways. One way is to increase the grinding speed, though this is not as easy as it may sound. The speed and pattern determine the metal removal rate. Faster is not always better. As speed increases, less metal is removed. This can undermine the goal of reshaping the head and removing the micro cracks. So, before increasing the grinding speed, a measure is put in place to ensure the quality of what is being left behind (see Figure 2). If grinding speeds are too slow, or if the wrong pattern is called, too much metal can be removed, resulting in poor productivity and a reduction in rail life. Use of the wrong patterns also requires more passes than may be necessary to achieve the desired result, which also reduces overall production.

Another way to improve efficiency is to identify the appropriate grinding cycles. The use of premium head-hardened rail, which is 30% to 40% more resistant to rolling contact fatigue (RCF) than head-hardened rail made only 10 years ago, has enabled UP to extend grinding cycles and the efficiency of the grinding program, overall.

UP and its service providers are reviewing the horsepower requirements for the various grinding patterns that have been used on the system. Improvements in stone technology may provide opportunities to increase horsepower and grinding speed with some patterns. UP is also reviewing the process of how it determines which patterns and grinding speeds to use. Under the current process, the grinding supervisor pre-inspects the grind locations and calls the first pattern and speed. On multi-pass curves the pattern is called on the grinder. This practice has worked, but there is a tendency to call the same handful of patterns because that’s what has always been done, rather than utilizing some of the other patterns that are available.

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