Civil Engineering Reference
In-Depth Information
fix will be possible. Good infrastructure decisions should be made before
they are urgently due.
What is more, a bridge is a capital investment. To decide to build
or reconstruct means that funds have to be expended this year for an item
meant to endure and provide service over decades. We incur a large debt
now, though we may not live long enough to experience the benefits. Unlike
most policy decisions, which are driven by short-term calculation and the
election cycle, infrastructure decisions (though they have current political
costs and payoffs) have to be made for the long run.
As compared to other public concerns, like declining exports or
increasing influenza cases, infrastructure is different again, because the prob-
lems it causes can be anticipated way ahead of time. Infrastructure causes
problems not because we're surprised by the unexpected (there are excep-
tions, of course), but because we've been ignoring the expected.
Since it is expensive and very time consuming to fix the bridge when it
is in danger of collapse, we should definitely not—in answer to this chapter's
question—wait until we get to it to cross it. On questions of infrastructure
planning, we should cross that bridge years before we urgently must.
THIS TOPIC
The topic that follows is a primer on the considerations at work when we
decide whether to build or rebuild a bridge. Since many of the considerations
resemble those for other kinds of infrastructure, some readers may also find
in this topic an introduction to infrastructure decisions in general, with
bridges as the running example.
Throughout, we want to share our affection for bridges, which are
among the most worthy and loved items in the built environment. The basics
of bridge engineering are accessible to anyone who has spent a year or two
in college, even if their major had nothing to do with science. To the viewer
equipped with those basics, the bridge reveals much more than is otherwise
obvious. Some may even become appreciators of bridges, hobbyists of sorts,
stopping now and then to gaze at a fine structure. A few, we hope, will take
up careers in engineering, planning, or architecture. (But we do not say much
about bridge architecture because on that subject, as contrasted to bridge engi-
neering and planning, there are already many topics accessible to beginners.)
If we have done our work well, our topic should also make clear
that a bridge is a product of many professions and multiple analyses: bridge
engineering for sure, but also financial analysis, transportation planning,
environmental studies, and public policy making. Our topic introduces many
of the kinds of planning at work. For citizens concerned about making better
bridges in their own communities, we offer our topic as a guide.
