摘要: |
Over 600,000 bridges in the United States are a critical component in
the transportation network for economy and society need. Assessing
bridge conditions and timely maintenance are critical to ensure bridge
health and cost-effective decision making in preservation activities.
Successful bridge-inspection programs nationwide is an important
element of assessing bridge conditions, and ultimately extending
service life of bridges.
Bridge owners nationwide have recognized the benefits of detailed
condition assessments through the use of the raw inspection
information, expanded performance measures, and bridge
management system deterioration forecasting and evaluation, which
are covered in the 2013 new American Association State Highway Transportation Officials (AASHTO) Manual for Bridge Element
Inspection.
The bridge condition rating of the United States is based on the NBI data of national highway bridges. Bridge
owners and stakeholders used to assess the bridge conditions and
make decision based upon these NBI data. The vast majority of the states have already employed
element-level inspection for more than a decade based on the CoRe
guide. The 2013 new AASHTO Manual, however, is significantly
different from the former CoRe guide. As a result, the difference in
frequency of inspections, element definition, qualifications of
inspection personnel, defeat description and inspection reporting from
state to state may cause inconsistency of data collection and
ultimately affect the quality of element-level data collected under
different states to be reported to the National Bridge Inventory (NBI).
As newer bridge types become more common, demand of new
guidelines for inspection ratings is needed to increase uniformity and
consistency of inspections.
To improve consistency in assessment of bridge element conditions
and establish accuracy levels for supporting bridge management
system deterioration forecasting and evaluation, the following
challenges must be addressed scientifically and systematically: (a)
there is a practical need for nationwide applications of high quality
element-level bridge inspection. A more comprehensive, reliable and
accurate levels for element conditions and defect types to accomodate
this need is urgent; (b) AASHTO 2013 Manual for data collection
provides criteria for element condition rating and defects description,
but without reliability-based calibration. The factors that affects the
quality and consistence of data collection can cause high variability.
Thus, reliability based indices to account for correlation between
levels of element conditions and critical factors (including inspector
qualification factor, structural importance factor, material
vulnerability factor, defect type/location factor, age factor, and
environmental factor) are necessary; and (c) Existing Manuals introduce
material distress for condition rating while overlook the assessment of
bridge element conditions that account for performance, probability
of failure and risk of failure, and thus cannot guarantee the desirable
performance. New guidelines should address these concerns.
Thus, to meet the requirements in the �Moving Ahead for Progress in
the 21st Century Act (MAP-21)� legislation and to ensure the safety
of the motoring public, a methodology for assisting bridge inspectors
and bridge owners to improve the quality of element-level bridge
inspection data and enhanced bridge management is needed.
Significant effort is required to develop the guidelines for practicing
engineers, from bridge inspectors, and inspection trainers, to local and
state Department of Transportation (DOT) bridge owners, to promote consistency in the collection of
reliable data that support bridge asset management practices. The
proposed research will address this important technical need by
characterizing quality of element-level data, generating a reliability based
correlation between levels of element conditions and critical
factors, and developing new data-driven based guidelines. |