IS IT WORTH IT? - Bridges - page 100

is not built. This could occur in a place with population growth and an
expanding road network. With the bridge unbuilt, the traffic distributes itself
differently (than it would have with the bridge built) and leaves many cars
idling in traffic jams downtown where the bridge should have been. To be
sure, the time will come when the US highway system will stop expand-
ing and when new modes of transportation will come to the fore, but that
will be a momentous change in society, and present speculation about that
future may not do much good now for a local bridge decision. Those who
oppose the bridge on environmental grounds should show not just that cars
cause pollution in general but that this particular project poses substantial
environmental harms.
In one respect, though, the concerns about neighborhood, economic
development, environment, and intangible effects coincide. Durable civic
infrastructure makes for a predictable urban environment and stable neigh-
borhoods. Ample long-lasting infrastructure provides a solid base for both
a vibrant economy and a healthier environment. We strongly suspect that
a bridge's greatest environmental disruption comes from being built and
demolished too often—when the bridge has turned into a disposable con-
sumer good, demolished and rebuilt periodically at great expense. And it
is the durable and magnificent bridge that brings the intangible benefits: a
lasting legacy and visible identity to a place. Cost-benefit analysis cannot
capture this intangible effect. Considering a proposed bridge, deciders should
rigorously inspect its internal cost-benefit, but should, thereupon, also reflect
on the bridge as an enduring monument.
Further Reading
Richard Hudson Clough, Glenn A. Sears, S. Keoki Sears, Construction
Project Management , 4th ed. (Hoboken, NJ: John Wiley, 2000) uses bridge
construction as an extended example for explaining the complexities of
cost estimating. A number of texts on capital investment introduce cost-
benefit—for example Diana Fuguitt and Shanton J. Wilcox's Cost Benefit
Analysis for Public Sector Decision Makers (Westport, CT: Greenwood, 1999).
Anthony Edward Boardman and David H. Greenberg's “Discounting and
the Social Discount Rate” examines some of the technical debates on the
proper choice of discount rate for public projects, but a basic background in
economics is needed; the article is on pp. 269-210 of Fred Thompson and
Mark T. Green's Handbook of Public Finance (CRC Press, 1998).
Alvin S. Goodman and Makarand Hastak introduce discounted-cost
benefit analysis alongside other techniques meant specifically for public
works investment—see chapters 8-10 of their Infrastructure Planning Hand-
book (New York: ASCE Press and McGraw-Hill, 2006). For a simple intro-