Monday, February 14, 2011

Cold Weather Can Cripple Railroads

With the temperature at 15 degrees below zero outside and the winds at 20 MPH, we had a wind chill near 42 below last week! It got me to thinking,  we all know how Colorado's snow can snarl a railroad, but what cold weather problems can railroaders face? Aside from the obvious frostbite, which can occur in as little as 5 minutes in these conditions, what else can extreme cold do to make work on a railroad even more difficult and strenuous?

Photo courtesy Kevin Morgan
First, engineers will tell you that extremely cold air can make setting the air brakes on the train very difficult. As air gets colder, it's ability to hold moisture diminishes.  The ice particles that remain in the air can cause brake valves to stick. When rubber hoses and gaskets freeze, they lose flexibility and strength. The colder it gets, the less flexible they become, and the number of leaks increase, making it harder for a train to "hold its air" and keep the air pressure up to 90 psi. Those rubber parts also have a higher likelihood of total failure, dumping the air and causing the train to go into a full emergency brake application, delaying the train until the failed part is found and replaced. If you're on the main line, that's one big inconvenience that ties up the railroad for minutes or hours on end.

Similarly, extreme cold causes metal to contract and go brittle. This results in track separation, broken rail, broken couplers, fractured springs, and other failures. An example of a broken coupler was caught later last week by You Tube user trainsruleandroll. Because welded rail is used extensively, lengths of continuous rail can contract beyond a critical point, causing the rail to pull apart, usually at a weld point. These pull-aparts can be mitigated by pre-stressing the rail and using clips that resist longitudinal rail movement.

Cold weather also can cause switches and derails to be more difficult to operate. Water can accumulate in the channels where the rods and switch points move, freezing them in place. The switch can't operate and the derail won't open or close without chipping out the ice, closing off routes that the railroad needs to use every day.

Despite being known for its ski industry, Colorado's average winter highs are usually above freezing, making cold weather equipment an option, not an absolute necessity in most years. When railroads defer maintenance and fail to invest in the infrastructure, it leaves Colorado's railroads more vulnerable to cold snaps. Thankfully, Colorado's Class I carriers, UP and BNSF, have kept up their trackage and rolling stock so that, while cold snaps inevitably do cause some delays, they don't cripple the railroad--or the state--indefinitely.