Agencies Gain a Bridge Lifecycle Assessment Tool.
Agencies Gain a Bridge Lifecycle Assessment Tool.
(2895 K)
Ehlen, M. A.
Bridge Builder, February/March 1999.
Keywords:
bridges (structures); design applications; building
economics; construction materials; life cycle costing;
new technology materials
Abstract:
State departments of transportation (DOTS) are currently
in the difficult position of having backlogs of bridges
to repair and increasingly smaller budgets. Nationally,
these repair costs are large, totaling as much as $90
billion, according to one report. Consequently, many of
these agencies are looking for ways to make their
bridges less costly to build and longer lasting. New
construction materials - such as high-performance
concrete (HPC), FRP composites, high-performance steel
and new applications of wood and aluminum - show promise
toward reducing the sum of a bridge's construction,
maintenance/repair, and disposal costs, also known as
its "life- cycle" cost. Their technical performance can
be verified using standard methods, but agencies still
need a tool for assessing the lifecycle cost
effectiveness of the materials. The National Institute
of Standards and Technology (NIST) has recently
completed the beta version of BridgeLCC, a Windows
lifecycle costing software program for bridge engineers.
Based on ASTM Practice E 917 for measuring the lifecycle
costs of buildings and building systems, BridgeLCC
provides a standardized, user-friendly tool for
comparing the lifecycle costs of alternative bridge
materials and bridge designs. The software is designed
to accommodate new construction materials but works
equally well for comparing conventional materials. The
program begins with bridge costs that are most familiar
to engineers: the "engineer's estimate" of initial
construction costs. When making a preliminary design of
a new bridge, engineers typically estimate the
construction costs of two or more alternative designs,
such as a concrete-beam design versus a steel-beam
design. BridgeLCC allows the user to input the
engineer's estimate for each alternative and then the
remaining costs in the ASTM Practice - operation,
maintenance, and repair (OM&R) and disposal costs.
Using an NIST cost classification scheme, engineers also
can enter user costs and third-party costs. User costs
are inccurred by automobile drivers on and under the
bridge, and third-party costs are incurred by third
parties who are not direct users of the bridge but are
affected by bridge construction activities, such as lost
revenues of businesses whose customers are blocked by
brdige work.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899