Monday, August 05, 2013

An industrial engineer’s dream job: Track maintenance

Software technology helps maintenance planners get the most out of tight work windows.

 

by David Burns, industrial engineering consultant

An industrial engineer’s dream or nightmare is maintaining railroad track, it all depends on your perspective. A specific task can require anywhere from one to 30 or more machines, each with a different designed rate of production, which then varies with machine condition, track condition, weather and even the mood of the operator. How do you get this “collection” of machines to work as a team to maximize output and minimize cost?

Unlike the North Americans, who selectively maintain track replacing ties and rail only when necessary, Europeans periodically renew track, cascading reusable material to secondary lines. Overall, this reduces long-term possession time for maintenance, which is critical when operating up to 250 trains per-day per-track. A Trans-European passenger train delayed in Italy because of track maintenance can have an impact on train connections in northern Germany. To minimize track maintenance possession and, more importantly, to ensure reliability for clearing the track for the next train, Europeans have developed very comprehensive track maintenance micro-planning software. This type of computer-aided planning has been used for years for management of complex construction projects.

Each machine owned by the railroad or contractor is carefully analyzed to determine the standard production rates under various conditions: ties-per-mile being replaced and track location relative to obstructions, such as bridges, restrictions such as embankments and multiple tracks or depth of or condition of ballast being cleaned. For each machine owned, labor requirements and standard capital, maintenance and operating costs are loaded through a series of dialog boxes into the program.

The detailed planning is undertaken by entering data into a series of site or operation-specific dialog boxes. These interrogate the planner to ensure that the required data is input. The planner enters the site location and the program downloads the relevant section from digitized track charts or, if those are not available, from a site visit. The work to be undertaken and the process to be used are entered in another dialog box. There are a series of boxes for machines, freight cars, labor, obstructions and restrictions that will impede production. The software has a series of prompts making various recommendations. If a specific high-speed tamper is to be used, it recommends the appropriate ballast regulator and dynamic stabilizer. It also recommends the appropriate labor force.

This type of software can plan by the day, hour or even minute. The shorter the track possession and the more complex operation, the more that can be gained by shorter time increments of timing. For example, for fast moving gangs such as surfacing, it is important to know exactly when the S & T crew should undertake its tasks.

Computerized micro-planning is even more important with variation of track possession as is typical with a freight railroad. The six hour promised possession, with maybe an hours notice, can be reduced to four hours. The roadmaster must reorganize the gang, by inputting the new possession into a laptop and then, almost immediately a new work plan will appear.  

At the end of the day, the roadmaster plots the shift’s production and can quickly identify problems with the gang or machines. For major operations, such as ballast cleaning or track renewal, some railroads monitor in real time the progress of each major machine so that problems can be quickly identified and measures can be taken to correct or minimize the impact of the problems.

With today’s ever-narrowing window for maintenance work, it is critical that the maximum amount of work is done during each track possession. It is reasonable to assume that the use of computer-aided planning will become more important as these work windows shrink.  

A relatively simple example of micro-planning for a ballast cleaning operation is shown in figure 1 and 2. Using this type of software it is not uncommon to find full track renewal of half a mile of track or more in a 3.5-hour (last train to first train) possession with a 60-man crew. Often, there is only a slow order on track rebuilt that day.

microplanning1

 

microplanning2

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