While stone bridges are renowned for their overall beauty and extremely
long lifespans they are also very expensive to build. To help keep
expenses down early railroads began engineering railroad bridges at first from wood and later from iron once it became available. Some of the earliest engineered railroad bridges included differing truss designs such as the Burr arch truss of 1817 and own lattice truss of 1820. One of the most common early such designs once iron was available was the Pratt truss of 1844, patented by Thomas and Caleb Pratt, and the Warren truss
of 1848. These designs can still be found on some railroad lines in
the country even today (and some have or are in the process of being
As steel became available in the late 1800s larger and more impressive railroad bridges
were constructed. Virtually all of these were of designs already on
the books, simply differing variations of them such as the cantilever truss and through arch design, the latter of which is perhaps most recognized as railroad bridges go in the New York, New Haven & Hartford Railroad's Hell Gate Bridge
which connects Queens and Manhattan over the East River. This
impressive structure was completed in September 1916 and remains an
important artery for Amtrak and freight trains today.
The most common railroad bridges are probably variations of the span plate girder designs. These bridges typically only span small streams, cuts or open areas and are relatively cheap and inexpensive to build. However, even some longer railroad bridges will be partially constructed of the span or girder design, it simply depends on how the engineer has drawn up the plans for a particular structure. For an excellent general overview of common railroad bridge designs please click here.
Railroad bridges will forever be an important component of the railroad infrastructure which allows trains to cross the country because obviously without them we could never have spanned the smallest stream to largest valley. It should also be mentioned that several bridges are nearing the end of their useful lifespan and will need to be replaced soon (or already have been). Obviously, it is necessary that these bridges are rebuilt sooner rather than later not only to keep an accident from happening but also to keep the flow of goods back and forth across the country. So, when state or federal money is being authorized to help in the building of a private, new bridge it is certainly going towards a worthy cause and is not a waste of tax dollars as these structures are very expensive to construct, even for large railroads (several million dollars per bridge is common these days).
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 colored photographs 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.