This Manual has been developed to assist Bridge Owners by
establishing inspection procedures and load rating practices that
meet the National Bridge Inspection Standards (NBIS). The Manual
has been divided into seven sections, with each section
representing a distinct phase of an overall bridge inspection and
load rating program.
Section 1 contains introductory and background information on
the maintenance inspection of bridges as well as definitions of
general interest terms. Key components of a comprehensive bridge
file are defined in Section 2. The record of each bridge in the
file provides the foundation against which changes in physical
condition can be measured. Changes in condition are determined by
field inspections. The types and frequency of field inspections are
discussed in Section 3 as well as specific inspection techniques
and requirements. Conditions at a bridge site may require more
elaborate material tests, and various testing methods are discussed
in Section 4. Field load testing is a means of supplementing
analytical procedures in determining the live load capacity of a
bridge and for improving the confidence in the assumptions used in
modeling the bridge. This is described in Section 5. Section 6
discusses the load rating of bridges and includes optional rating
methods. The evaluation of fatigue and other special conditions are
discussed in Section 7.
The successful application of this Manual is directly related to
the organizational structure established by the Bridge Owner. Such
a structure should be both effective and responsive so that the
unique characteristics and special problems of individual bridges
are considered in developing an appropriate inspection plan and
load capacity determination.
The purpose of this Manual is to serve as a standard and to
provide uniformity in the procedures and policies for determining
the physical condition, maintenance needs and load capacity of our
Nation's highway bridges.