Once the benefits of CWR were realized the industry quickly began
replacing its most heavily trafficked main lines with the new type of
railroad track and by the 1970s most of these routes employed it. Even
better for railroads was the fact that CWR did not necessarily have to
be purchased new. If a rail line already contained the desired track weight (such as 100, 110, or 120-pound rail) it could simply be welded into strings and relaid costing only the maintenance time required.
The one drawback to CWR is its tendency to kink, or turn into
spaghetti, during the high heat of summer. Known as sun kinks this
phenomenon can result in either slow orders or the movements to be
suspended entirely until the night or late evening when cooler
temperatures allow the track to settle back into place. However, warm
temperatures are needed when installing CWR as doing so in cold weather
when the steel tends to contract can result in buckling and warping when
warmer weather prevails.
During the late 19th century railroad track could weigh less than 80 pounds (typically measured per yard) but as the decades passed and locomotives and cars grew larger the rails have had to follow. Today, the major rail arteries around the country employ track that weight at least 120 pounds but some can weight up to 140 pounds. Interestingly, relics can still be found out there, particularly on tourist railroads that can contain railroad track dating back to the late 1800s and be no heavier than 90 pounds.
Today, with trains so heavy and the required weight of the track now well in excess of 100 pounds new rail can be very expensive so when purchasing it railroads try to closely match it with whatever type of service it is intended for. For instance, if a rail line only sees short or infrequent trains such as on branch lines these typically are not as heavy as long coal drags, which will, naturally, require much heavier rail. In any even, early railroad track has given way to the much heavier and more comfortable (in terms of the ride) ribbon rail. And, CWR has become a science into itself as railroads must make sure they install the rail correctly and in warm enough temperatures to keep kinking from occurring.
If you are interested in fallen flags and classic systems before the modern merger movement took hold I would suggest purchasing one, or all three volumes of Mike Schafer’s Classic American Railroads series of books. The publications feature a wealth of information and are loaded with coloredphotographs covering names like the Baltimore & Ohio, Santa Fe, Pennsylvania, Milwaukee Road, and lots more. If you have any interest in most famous bygone railroads which once operated in the U.S. I would strongly recommend picking up one, two, or even all three of Mr. Schafer’s book. I truly cannot say enough just how enjoyable and fun they are to read and peruse through.