Optimizing Design and Maintenance Practices
Design and maintenance are two of the most crucial aspects of managing wheel/rail interaction on rail freight and transit systems. When it comes to wheel/rail interaction, this also applies to the forces and friction that are generated by vehicle/track interaction.
Optimizing friction management is an ongoing project on the Union Pacific. Large scale tests, such as UP's Tehachapi Study have shown that optimal friction management offers an attractive return on investment, but that the cost of optimizing the entire system at once is prohibitively high.
In their article on "Optimizing Friction Management and Curve Elevation on Union Pacific," Mike Gilliam and Russell Rohlfs report on the incremental steps UP is taking to optimize various aspects of its friction management program. These include bulk-filling lubricant applicators, customizing maintenance schedules and remotely monitoring applicator performance. "Since upgrading friction management units in order to keep up with the state-of-the-art is prohibitively expensive, UP is examining ways to increase the reliability of the existing equipment," they report.
UP is also making efforts to extend wheel and rail life through optimizing curve elevation. Proper curve elevation ensures that both the high, and low rails wear evenly – thus extending overall curve rail life, and synchronizing replacement and maintenance cycles for each rail.
With geometry cars taking measurements every 2 to 10 feet, UP is able to launch site-specific investigations into curve areas that show symptoms of improper elevation and abnormal wear. Accurate measurements also allow UP to quantify rail savings and the return on the investment associated with correcting poor conditions.
Mike Gilliam and Russell Rohlfs also report on how Union Pacific looks at its rail grinding program as a way to control rail wear, and to extend the asset life of rail and other track components. In their article on "A Measured Approach to Improvements in Rail Grinding," they report on how 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."
Pre-engineering the Wheel/Rail Interface
Detailed planning during the design phase of a rail transit system is the best way to eliminate surprises and mitigate unexpected costs down the road. Organizations like National Research Council of Canada's Centre for Surface Transportation Technology (CSTT) often uncover problems that can be traced to incompatibilities between vehicle/track and wheel/rail designs that were built into the system during the design phase.
In his article on "Pre-engineering the Wheel/Rail Interface," Rob Caldwell, a senior engineer at the CSTT, discusses the types of systemic problems relating to poorly engineered wheel/rail interfaces, and the steps that can be taken to avoid and proactively manage them. "There are significant benefits from properly addressing the wheel/rail interface, and serious consequences to allowing the interface to govern itself," Caldwell says.
This is not to suggest that management of the wheel/rail interface is an easy task. As Caldwell points out: The wheel/rail interface is extremely complex, with many variables drawing on four different disciplines that have a first order effect on the function, cost, and durability of the overall system. "Proper design and implementation is a matter of matching various design specifications and ensuring that there is harmony throughout the entire wheel/rail system, and not just the stand-alone components."
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