Cities and Their Vital Systems Infrastructure Past, Present, and Future (1988) / Chapter Skim
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15 Longevity of Infrastructure
15 Longevity of Infrastructure
Pages 312-332
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From page 312... ...
If these structures approach immortality, then they exist as part of the inheritance of each generation, and each generation needs only to maintain its inheritance and to add infrastructure capital as the systems grow. If, on the other hand, the major capital items of infrastructure are relatively short lived, then each generation has both a greater obligation to supply its own infrastructure capital and a greater opportunity to affect the character of its own infrastructure.
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From page 313... ...
Electric Power Plants Analysis of the longevity of energy-producing devices raises a moral issue: what responsibility do those who build polluting and possibly dangerous electric power plants owe to future generations? It could be argued that, insofar as these devices are inexpensive to operate, the generation that paid for their construction was compensating later generations for any such burden with the gift of relatively cheap electricity provided the later generation does not have to rebuild the powerproducing devices.
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From page 314... ...
This is the case for solar-based devices-solar cells, dams, wind turbines for which the primary energy, sunlight, is "free." To a lesser extent this is true also for nuclear energy sources fusion and breeder reactors for which the fuel cycle costs are expected to be low and practically independent of the supply of uranium. Even nonbreeder reactors have fuel cycle costs that are below the fuel cost of fossil plants.
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From page 315... ...
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From page 316... ...
Thus, the original incentive to retire an old fossil plant lower thermodynamic efficiency than its newer replacement is no longer compelling. The electric utility industry and its suppliers have devoted much attention recently to the extension of the life of existing power plants, both fossil and nuclear.
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From page 317... ...
Thus, France's 66 reactors occupy 21 sites, or about 3 reactors per site, whereas in the United States, 129 operating and planned reactors will occupy 76 sites, or 1.7 reactors per site. Although the evidence is less clear for fossil power plants, it seems likely that new, large fossil power generators will be added to existing sites rather than being built on new sites.
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From page 318... ...
At about this same time, two major dam failures focused attention on dam design, theory, and engineering. The 35.7-m-tall Habra Dam in Algeria was completed in 1870 but failed completely in 1881 when water rose 4 m above the intended maximum; in 1895 the 14-year-old, 15-mhigh Bouzey Dam in France failed with a loss of 150 lives.
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From page 319... ...
The dam was completed in 1916, received major modifications in 1925, and was acquired by TVA in 1939. A 1983 TVA evaluation noted four significant deficiencies: dam instability, insufficient spillway capacity, leakage (which totals as much as 5.5-m3/second under and around the dam'; and deterioration and inadequacy of the power generation facilities.The TVA evaluation said in part, "based on current design criteria, the dam is not safe against overturning or sliding" (TVA, Hydropower Planning Section, 1983, p.
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From page 320... ...
Siltation, another major reason dams lose their usefulness, has brought TVA to abandon powerhouses and sell dams to communities for nominal fees. A case in point was the Davy Crockett Dam in Tennessee: the dam, which was 90 percent silted up, was converted into a wildlife refuge.
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From page 321... ...
The bridge was reconstructed at least twice before a stone bridge was begun in 1176. As in other civil engineering works, bridge building has progressed through a sequence of building materials and construction methods with a large empirical foundation and gradually emerging science.
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From page 322... ...
This period between 1900 and World War II saw rapid growth in the number and size of bridges and in related technical knowledge, of which the most important was the development of reinforced concrete (DOT, Federal Highway Administration, 19771. The first use of prestressed concrete in a U.S.
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From page 323... ...
1071. Throughout history, good road maintenance has generally been the product of stable central and local authority.
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From page 324... ...
After a trend toward widening existing roads in the United States has come the development of special, high-capacity roads. In fact, the evolution of the nation's roads reflects their changing role in human affairs in addition to the changing technology of roads, road building, and road use.
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From page 325... ...
In many instances a power plant or a bridge is taken out of service not because it no longer can perform its original function but because a competing device can perform the same function less expensively or because the original function is no longer very useful for example, the bridge is too narrow for the increased traffic it must now carry. In the following paragraphs, however, the focus is on the narrower issue of physical obsolescence or failure: Can we identify in the design and construction of
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From page 326... ...
~/~4~;f t/wfowr~ Mar a- ~w a. ~ I Mar FIGURE 15-2 The road's progress as predicted by Robert Phillips to the Royal Society, 1737.
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From page 327... ...
Such elaborate monitoring ought to give early warning and therefore help forestall incipient failures. Third, early pressurized water reactors in nuclear plants were designed under the assumption that the steam generators would last as long as the plant.
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From page 328... ...
Power plants traditionally have been expected to last 25 to 30 years, largely because history has shown them to become noncompetitive by then, and their design was geared to this perception. Today that perception has changed, in part because the plants have reached a thermodynamic ceiling.
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From page 329... ...
A second incentive toward centralization of facilities is to be found in the current reluctance to accept any device that the public finds environmentally threatening, whether it is a dam, power plant, transmission line, or waste disposal facility. The situation is perhaps most clear-cut for power
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From page 330... ...
Certainly the electric power industry's experience in the siting of transmission lines and of coal- and nuclear-fired generating plants gives us little assurance that the creation of future infrastructure will be easy and without political ferment. Perhaps this characteristic, more than any other, will argue for maintaining the existing infrastructure, or at least the existing sites, rather than arousing the passions of those who would be inconvenienced by, or who might even believe themselves to be susceptible to harm as a result of, new infrastructure.
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From page 331... ...
The energy-generating system, although it is aging, seems likely, by and large, to last longer than was expected. On the other hand, there is little evidence that roads, even modern ones, will last much longer than their design lifetimesthat is, unless they undergo costly repairs.
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From page 332... ...
Secaucus, N.J.: The Citadel Press. Tennessee Valley Authority, Division of Water Control Planning.
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