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Why is history important to today's engineer-part two "the Wrong Type of Snow" and other excuses.

Posted on March 12, 2014 at 6:25 PM

 

If you have checked out my web site-and thank you for doing so !- you may have noticed the nice photograph of three Atlantic Coast Line diesel locomotives sitting at Harrison NJ in February 1958. While not only a nice photograph, it has a lot to do with the theme of this, my third blog.

 

If you look closely, you will see that these diesel units are sitting under an overhead electric power system. Normally, these locomotives would be exchanged for electric locomotives some 210 miles south of this point at Washington DC. So what are they doing this far north? The simple answer-snow of a type that was not designed for and which ended up crippling a railroad.

 

From February 14 to 17, 1958, the eastern United States was hit by several snow storms. One of the storms produced a very fine variety of snow-named “Diamond Snow” which was of a very fine, crystalline variety. The electric locomotives then used by the Pennsylvania Railroad on its electrified line between Washington DC were known as GG-1 units. All 139 of the locomotives had large air intakes which were used to send large amounts of air to cool the electric motors. In order to prevent dust, dirt, and snow from entering into the sir cooling system, the air intakes were equipped with filters. These filters worked very well, until the day that the diamond snow started to fall.

 

The snow particles were small enough to be easily ingested by the air intakes despite the presence of the filters. They proceeded to enter the interior of the motor cooling systems, where the heat melted them and then the water dripped onto the electric motors and shorted them out. Within a few hours, 138 of the 139 locomotives were disabled. In order to maintain some resemblance of service, the railroad used diesel locomotives for most of the route between Washington and NY, only changing power outside of Penn station since diesel locomotives were not permitted to operate in the under river tunnels.

 

After studying the problem and trying several different types of filter material, the railroad settled upon fine French linen filter material, along with using the then new epoxy resin to provide a better insulation coating on the motors.

 

The problem and the solution were widely reported in the professional press at the time, and many other railroads pre-emptively adopted similar solutions in order to prevent damage to their locomotives.

 

Now let us fast forward to February 1991and cross the Atlantic. The London area was experiencing an unusually cold and snowy winter. Many cars in the fleet of electric trains were experiencing failures in their electric motors, leading to massive disruptions. During an interview with a newspaper, a senior railroad official stated that British Rail was having problems with the type of snow which was not usually encountered in the UK. The newspaper man stated that it was “The wrong type of snow” and this remark was then mistakenly attributed to British Rail. Again, the snow was extremely fine and the existing air filters were not designed to exclude the fine crystals. Here again, the snow melted and despite the improvements in electrical motor insulation, the water dripping onto the motors caused short circuits which severely damaged the motors. Eventually some old timers remembered the 1958 snow storms in the US and new filter material of a type to exclude the fine snow was adopted.

 

Now let us fast forward to December 2009. A series of heavy snow storms affected the British Isles and France. Several Eurostar trains operating in the Channel Tunnel experienced traction motor failures while operating through the tunnel. Some 2000 passengers were trapped in the dark. The investigation afterwards revealed that fine snow was ingested into the air cooling ducts and between the heat of the motors and the internal heat of the Channel Tunnel, the snow melted, water dripped onto the motors and caused them to short out.

 

I think that you may guess by now where I am going with this! The winter of 2013-2014 has been one of the harshest in many years. Much new equipment has been designed and put into service on the railroads, and still, we hear of stories of equipment problems during cold weather.

Not all of the problems have to do with traction motors or fine snow. But cold weather has been around a long time. Railroads such as the Canadian Pacific, Canadian National, Great Northern, etc. have long operated during some of the harshest winters and managed to perform well. They designed their equipment with piping vulnerable to freezing being located inside equipment, heat tracing was applied on outside lines and several back up heat systems were used to prevent freeze ups. Yet, when new equipment is placed in service, it seems as if no one goes back and tries to see what was done in the past. Yes, diamond snow is rare, but it does happen. Below zero temperatures are rare in some areas, but they do occur. So why do we still have problems with equipment in cold, snowy weather? Why are exquisitely engineered cars built to the latest standards of rider safety knocked out of service because water gets ingested in their cooling systems? Wrong kind of snow? Wrong kind of cold? Wrong winter?

 

Anyway, another winter storm is upon us and I have to go out and clear my driveway of the wrong kind of snow. The kind that falls on MY driveway!

 

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