Articles

Sharing Canada's Experience with Long Freight Trains

Canadian railways look forward to sharing what they've learned about the operation of long freight trains at a conference next June in Calgary, says Michael Roney, General Manager Technical Standards & Chief Engineer, Engineering Services of Canadian Pacific.

The best arrangement is locomotives at the front and rear of the train as well as in the middle, explains Roney, chairman of the International Heavy Haul Association and cochairman of its 2011 conference in Calgary that will look at railroading in extreme climates.

Distributing the locomotives through the train "stabilizes and equalizes the forces exerted on the freight cars," he adds. That reduces the pushing and pulling on the cars and that produces less wear and tear on them and the rails. The result is a safer operation compared to conventional trains where all the locomotives are at the head end. Even with locomotives at the front and back of the train, there's more push and pull on the cars than in a distributed power train (DP) as the train slows or picks up speed.

The difference between a DP and a conventional train shows up in track monitoring equipment, he adds. “You can tell from the monitors by the amount of lateral forces in the train” whether it’s a DP train. They generate 20% less lateral force on the tracks than conventional trains.

In a recent report, the Transportation Safety Board noted that since 1995, “freight trains have increased 25% in terms of size and weight making it all the more important that freight cars in those trains are positioned to reduce the stress on them. If you liken a long train to an accordion, pulling forces tend to separate cars and pushing forces will compress them together.”

Transport Canada said a research project, that’s expected to finalize its findings this summer, is examining the influence of grades, curves, distribution of power and train handling practices on the long trains.

In addition, the industry has brought improved software on line to better control the factors that affect these longer, heavier trains with respect to the geography of the terrain over which they operate, the department said.

The 35-tonne Heavy Axle Load Testing Continues at FAST

Joseph LoPresti and Semih Kalay

Traffic Growth and Heavy Axle Load Research at FAST
North American railroads have experienced significant traffic growth over the past 20 years. Some studies have projected that rail freight traffic will double in the next 20 years. Railroads are continuing to develop cost-effective ways to safely increase capacity. One strategy that North American railroads have used is to raise the allowable axle loads for freight cars. Research funded by the Association of American Railroads (AAR) and the industry has been helping minimize the adverse effects of increased axle loads.

Since 1988, testing at Facility for Accelerated Service Testing (FAST), Pueblo, Colo., has been a mainstay in the AAR heavy axle load research program. Tests are updated at the direction of railroad committees to assure that the program meets the changing needs of the industry. In the past year, there have been significant changes and additions to FAST.

Figure 1 shows a different train that is now operating at FAST, which should enhance safety, increase productivity, and reduce maintenance costs. The Union Pacific (UP) Railroad provided 110 current generation 315,000-pound gross rail load aluminum coal cars for use. Norfolk Southern, UP, and CSX provided the use of modern, high-horsepower, fuel-efficient EMD SD 70M and SD 70 MAC locomotives. Fuel consumption has been reduced by about 20 percent, and the new locomotives facilitate unmanned train operations that are now standard practice at FAST.

A riveted steel bridge span built in 1912 replaced a 40-year-old welded steel span. The riveted span is typical of hundreds of spans currently in service in North America. Testing at FAST will provide a better understanding of how these spans react to heavy axle loads, which will be valuable as railroads make decisions on upgrading or replacing them to accommodate heavier cars. Strain data collected at FAST can be used in fatigue models to estimate remaining bridge life.