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Issues Impacting Bridge Painting: an Overview
Chapter 1. Introduction The economic health of a nation is dependent on its ability
to engage in commerce. This ability is directly related to
the capability of its infrastructure to efficiently and safely
respond to the demands placed upon it, not only by its users,
but also by the environment. A recent survey (1993) indicates
that of the nearly 600,000 bridges tabulated, just over 190,000
bridges were considered substandard.(1)
While the reasons for this classification are varied, a growing
number are the result of the presence of lead-containing
paints previously applied for corrosion protection. Both
recently adopted and proposed future regulations have resulted
from a growing awareness of the need to protect the environment
from uncontrolled pollution, and to safeguard the health
of workers engaged in renovation as well as that of the general
populace. In 1992, Congress requested that the Federal Highway
Administration (FHWA) commission, through the competitive
bid process, a study to evaluate the state of technology
as it pertains to the rehabilitation of bridges. In particular,
the study was to evaluate how lead-containing paints are
removed and tested, and to evaluate alternate coating techniques.
To this end, six technical and three management and reporting
tasks were initiated. The technical tasks performed were:
Task A. Economic Evaluation
Task B. Worker Protection/Paint Removal
Task C. Waste Treatment and Disposal
Task D. Alternative Coatings
Task E. Accelerated Testing
Task F. Productivity Improvement
The evaluation of coatings, materials, and
processes for the rehabilitation of bridges is based on their
ability to
meet regulatory standards, perform in the field, and be
economical.
Task A developed an economic model by which
rehabilitation options can be ranked in terms of long-term
benefits versus
present-day expenditures. As with any study, information
has been gathered from the literature and by experiments
done in the laboratory. However, only when tested in the
field can such information be validated. To that end, in
cooperation with the Illinois Department of Transportation
(IDOT), field tests for the various tasks were performed
on a stretch of I-55 near Wood Avenue in Chicago, Illinois.
Several methods of paint removal were tested as part of
task B, and debris was collected for analysis in task C.
Several
selected alternative coating systems typified by painted
and metallized panels were deployed at the test site for
environmental exposure testing as part of task D. Furthermore,
the feasibility of extending laboratory testing into the
field was evaluated as part of task E. Finally, the deployment
of sensors in the field to evaluate surface preparation
and the condition of existing paint systems was successfully
demonstrated as part of task F. |
