The deck of a highway bridge serves both structural and
functional purposes for the structure. As a structural
component, it provides the load path to safely transfer forces
from wheel loads to the supporting superstructure and
substructure elements. It may also contribute, through
composite action, to the performance of primary superstructure
components. Equally, the construction and condition of a
deck directly impacts serviceability or the ability of the
structure to safely and efficiently carry highway traffic by
providing smoothness, skid resistance, and resistance to
deflections under wheel loads. The riding surface of a
highway bridge deck should provide a continuation of the
pavement segments that it connects. The surface should be
free from characteristics or profile deviations that impart
objectionable or unsafe riding qualities. The desirable qualities
should persist with minimum maintenance throughout the
projected service life of the structure.

Roughness, cracking, spalling, scaling, and poor skid
resistance are defects that result when the many details that
influence their occurrence are not given sufficient attention.
Recognition of the interaction of design, materials, and
construction practices, as well as environmental factors, is the
important first step in achieving smooth and durable decks.

Many decks remain smooth and free from surface deterioration
and retain skid resistance for many years. When
deficiencies occur, they usually take one of the forms
described in this guide. The contribution of various aspects
of deck construction to defects is discussed and guidelines
based on theory and experience presented that should reduce
the probabilities of occurrence to acceptable levels.