One of the first railroad bridges to be built in the country is credited to the Baltimore & Ohio Railroad which constructed its Thomas Viaduct in 1835 located at Elkridge, Maryland over the Patapsco River. The bridge
gained its name for the B&O's first president, Philip E. Thomas and
at the time of its construction was the world's longest masonry bridge and the first curved structure of its kind. Even today it remains the largest bridge
of its type and still carries regular freight and passenger trains to
this day, a testament to the strength and longevity of not only its
stone construction but also the masons who built it.
Other famed stone bridges around the country include the Pennsylvania Railroad's Rockville Bridge
near Harrisburg, Pennsylvania crossing the mighty Susquehanna River.
This massive structure is 3,820 feet long and includes 48 arches. it
opened in 1902 and still carries Norfolk Southern Railway freight trains
and Amtrak passenger trains today. Although not built of stone it should be noted that one of the most famous arched railroad bridges in the country is the Delaware, Lackawanna & Western Railroad's Tunkhannock Viaduct. Topping out at 240 feet above the valley floor and roughly a half-mile long at 2,375 feet the railroad structure is a striking sight (made all the more impressive by Lackawanna R.R. located across the center arch).
|The famous bridges at Harpers Ferry, West Virginia spanning the Potomac River are seen here in October of 1979 as a Chessie System freight heads eastbound. Both structures were built by the Baltimore & Ohio and remain in use today.|
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).
|A westbound Burlington Northern stack train crosses the Wenatchee River at Dryden, Washington led by SD40-2 #7040 and a long string of other power on May 21, 1984.|
For more reading about railroad bridges you might want to consider the book North American Railroad Bridges
from noted author Brian Solomon. Solomon's book explores the history
and technological development of railroad bridges and highlights all of
the most common designs to ever be used in this country. The book as
received excellent reviews by readers and is a great resource on the
subject. If you're interested in perhaps purchasing this book please visit the link below which will take you to ordering information through Amazon.com, the trusted online shopping network.