Readers’ Forum
OPINION
who’s interested. As an object lesson in the stability of railcars, Mr. Spencer should observe a double-stack container train. These trains have cars that load two levels of shipping containers, with the top of the upper container approaching 20 feet above the rail. While the containers are somewhat lighter than a loaded tank car, there are no stability problems with them. In fact, these trains are some of the fastest in North America; BNSF Railway routinely runs them at 70 miles per hour in some regions. Mr. Spencer also states that, “Some of the older tanks have gone swayback.” I am not sure exactly what this means, but I suspect he is referring to tank cars that are a little higher at each end, with a noticeable slope down towards the centre of the car. These are called funnel-flow tank cars — it is not a problem but rather an intentional design feature to help facilitate unloading. Mr. Spencer is correct that the basic wheel design has remained unchanged for many years, but over years there have been slight changes to wheel design to improve tracking, wear, wheel life, and safety characteristics. The wheels most certainly do not “limit the speed that a train can travel” — the steel-wheel- on-steel-rail speed record is currently held by a French TGV that reached a speed of 574.8 km/h in April 2007. The European rail and wheel profiles are similar to North American standards, and the train had only superficial modifications (such as reduced number of cars and slightly larger-diameter wheels) to reach this speed. Mr. Spencer’s comments about dealing with curves are more or less correct — each wheel set is a rigid assembly, but given the relatively generous curve radii on mainlines, this is not a significant concern. Wheels do, in fact, have a slight differential built into them. Engineering is the application of science and technology to solve problems; as with all things, this involves balancing many factors, including safety and cost. We certainly have the means to move rail traffic faster; I have ridden on passenger trains at speeds around 300 km/h in at least four countries. But the
Finally, the axle/wheel design does include a feature to handle curves and it does it well. The wheel profiles are not cylin- drical but cone shaped. I’m sure other writers on the subject will have brought up this important point, so I won’t go into detail. There have been other designs to look at this issue but multi- part wheel sets are not as reliable as the single-piece wheel sets that we have now. Single-piece sets also change-out very quickly, keeping cargo on the move. The biggest wheel wear is most likely due to locked brakes in emergency stopping situations. Due to some unfortunately spectacular failures, the public now hears about almost every rail-related incident. But they do happen very rarely. We have all personally seen many road- related incidents that do not make the news. Engineers have been very hard at work on improving what is a timeless — but very functional — design. HARALD WITZLER, P.ENG. Sherwood Park
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Mr. Spencer is correct in that there are safety concerns with modern railcars, just as there are with any modern technology. This came into the media spotlight following the Lac Mégantic accident, especially as it applies to the Class 111 tank car, as defined by the U.S. Department of Transport. A quick review of Trains magazine over the last year or so will reveal a number of investigations underway to improve the safety and crash- worthiness of these tank cars. Mr. Spencer makes the assertion that tank cars have “such a high centre of gravity [that they] are inherently unstable.” This is false. There are thousands of tank cars in daily revenue service across North America and there is no concern with them rocking themselves off the track. Regulations specify the maximum height for the centre of gravity of a railcar; a Google search will confirm that, for anyone
48 | PEG SPRING 2015
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