Railroad track has two primary functions: to transmit train weight to the roadbed, and to
guide the wheels of trains in the desired direction. To carry out these purposes, various forms of
track have been and are being used; however, the use of two rails in basic. The differences in
track construction involve variations in the form or shape of the rails and in the means of
holding the rails in place.
In the United States, the earlier forms of track consisted of two timbers running
longitudinally with the right of way. Fastened to the upper surface of each timber was an iron
strip on which the car wheels rolled. These timbers were known as stringers and rested on
granite blocks, but the blocks proved unsatisfactory because they cracked in freezing weather and
moved in mud, disturbing proper gage. Wooden stringers also failed the test of long-time usage.
The iron strips wore badly and often became unfastened, especially at the ends. The curled-up,
unfastened iron strips, commonly referred to as "snake heads," fouled operations by delaying or
severely damaging trains.
Prime effort then was directed toward finding a more satisfactory rail. British practice,
on which most early American procedures were based, involves a solid, peculiarly shaped iron rail
which necessitates cast-iron chairs or pedestals for support, as shown in the inserted sketch. This
complicated system of rail support was far too costly for use in the United States where
exceedingly long distances had yet to be spanned by rail lines.