A bridge is a structure that carries a roadway over a depression
or an obstacle. Bridges may be classified in different ways. Two general
classifications, for example, are highway and railroad bridges. One of
the bridges most commonly found in the TO is the nonstandard fixed bridge.
This chapter discusses the construction of both the substructure and the
superstructure of this important military bridge.
A bridge completely supported by its two end supports (abutments) is
called a single-span bridge. A bridge having one or more intermediate
supports between the abutments is a multispan bridge. All supports of
a fixed bridge transmit the load directly to the ground.
A nonstandard fixed highway bridge (Figure 10-1) is a semipermanent
bridge constructed from local materials or Class IV materials drawn from
a depot. It differs from standard bridges, which are prefabricated bridges
assembled at the site. The most common nonstandard fixed highway bridges
are the simple, stringer-type (the stringers being logs) and those made
of structural grade timber or structural steel.
A military bridge has two principal parts: the lower part (substructure)
and the upper part (superstructure).