Cities and Their Vital Systems Infrastructure Past, Present, and Future (1988) / Chapter Skim
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2 The Dynamic Characterization of Cities
2 The Dynamic Characterization of Cities
Pages 22-70
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From page 22... ...
has used modes of transportation to classify urban development into four eras or epochs: sail-wagon, iron horse, steel rail, and auto-air-amenity. Each epoch sees unique metropolitan growth patterns being molded by the transportation available.
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From page 23... ...
This requires grouping cities according to a "phylum," that is, an organic group in which all members exhibit a basic similarity of ground plan and evolve through similar stages, yet are completely dissimilar from one another. One of the grey areas in this arena is the classification of cities on the basis of their infrastructure.
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From page 24... ...
Eventually, formal models might be constructed to describe possible changes for a set of cities with similar ground plans. EVOLUTION OF A CITY The figures that follow are pictorial representations of the evolutionary path taken by certain attributes of the city of Austin.
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the argument that the effect is due to the inclusion of undeveloped land. One immediate conclusion to be drawn from Figure 2-6 is that growth in the number of street miles in the city has lagged behind growth in population over the last 70 years.
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As might be expected from the preceding discussions, both the number of vehicles per street mile and the number of vehicles per square mile have increased exponentially since 2000 .
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O 27 '15 20 25 30 t3540 45 50 55 t60 65 70 75 80 85 Year (1 900's) FIGURE 2-S Density of street miles in Austin, l91S-1985.
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and street miles (mean = 0.4, standard deviation = 0.1) , also exhibit a similar consistency over a long period of time (Figures 2-12 and 2-131.
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to the number of restaurants is not unique to Austin. In San Antonio the number of people per restaurant has a mean of 809 and a standard deviation of 359 (City Directory of San Antonio, 1900-1985~.
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construction activity. The number of law firms could indicate essential aspects of the city and the type of activity on which it thrives.
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the number of electric meters and water meters could therefore be used to characterize the composition of the housing market (Figure 2-161. Further, the volume of telephone numbers in use may reflect not only the average family size (assuming one telephone number per family)
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lent scale for the comparison of cities would be per capita annual power consumption because it measures an infrastructural attribute that is often of prime concern (Figure 2-191. Cities that use electrical energy for transportation including escalators and elevators as well as rapid transit systems may show higher per capita consumption of electric power than other cities.
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Current levels of postal revenues could be a strong indicator of the nature and level of the business of the city. It would also be interesting to examine the levels of overnight private letter and package delivery services.
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IAN, ARDEKANI, GOVIND, AND DONA 'at '45 '50 '55 '60 '65 '70 '75 '80 '85 Year (1900'S) FIGURE 2-19 Annual power consumption per capita in Austin, 1925-1985.
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The selection of these regions is based on Maurice Yeates's North American Urban Patterns (1980) in which he subdivides North America into major urban regions using three criteria: (1)
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Yet New York is a considerably less compact city than that proposed by Dantzig and Saaty (1973) in Compact City A Plan for a Liveable Urban Environment and less compact than the more decentralized version of this concept recently set forth by Beck (19861.
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From page 38... ...
Variable l Pon,~l~tion 28 Hospital beds 29 Airports 30 Airport plane departures 31 Enplaned passengers 32 Parks 33 Stadiums 34 Cemeteries 35 Churches 36 TV stations 37 Radio stations 38 39 40 41 42 43 44 45 46 2 Area 3 Population density 4 Perimeter 5 Form factor 6 Percentage of perimeter on water 7 Median age 8 Average income 9 Revenue 10 Expenditures 11 Bonded debt 12 Households 13 Families 14 Workers employed in central business district 15 Workers using public transit 16 Total employment 17 School enrollment 18 Postal revenue 19 Library budget 20 Library books 21 Libraries 22 Schools 23 Colleges and universities 24 Notable tall buildings 25 Hotels 26 Hotel rooms 27 Hospitals and clinics Theaters Bus transit route length Buses Rail transit track length Rail cars Transit ridership Car registrations Length of freeways Length of nonfreeway roads 47 Bridges 48 Tunnels 49 Water lines 50 Water use 51 Sewer lines 52 Sewage treated 53 Solid waste generation 54 Telephones 55 Residential electric bills aSee Appendix A for definitions of selected variables. Of 300,000 passengers per minute.
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From page 39... ...
In the first stage the dimensionality imposed by the set of 40 variables for which data are available for all eight cities is reduced by clustering the variables into nine disjoint subsets or clusters such that any one cluster contains at least two but not more than seven variables. In the second stage the clusters are subjected to factor analysis to estimate the relative leverage exerted by each variable in the cluster.
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From page 40... ...
On the basis of the retained principal components, the observed variables are then ranked according to their communality estimate, which is the amount of variance held in common with the other variables in the cluster. This amount is numerically equal to the sum of the squares of factor loadings (Kendall, 19751.
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From page 41... ...
Utilities Telephones 1.321853 0.847 Water use 1.145786 0.837 Electric bill average 0.532361 0.783 5. Economic Expenditures 3.200759 0.975 Revenues 2.122249 0.970 Postal revenue 0.818851 0.942 Bonded debt 0.651224 0.741 CBDb employment 0.175524 0.604 Employment 0.030281 0.573 Average income 0.001112 0.517 6.
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From page 42... ...
number of enplaned passengers, (7) per capita car registrations, (8)
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From page 43... ...
The similarity in shape and the difference in size of the snowflake diagrams are expected to remain relatively the same if other variables in clusters 2 through 9 of Table 2-3 are to be plotted on their respective axes, given that the pairwise correlations among variables are positive. Therefore, the similarity in the general shape of the diagrams for Chicago and Atlanta indicates that these two cities have similar characteristics.
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They are both stretched out along axes 2 and 7, and both show small to intermediate values along axes 3, 4, 5, 8, and 9. Houston, however, is characterized by a lower number of per capita car registrations (axis 7)
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From page 45... ...
It is also not surprising that Atlanta, Cincinnati, and Miami all have relatively high numbers of hospital beds per 1,000 population and that New York is characterized by high per capita expenditures and numerous tall buildings. What is not so intuitive are all the variables that are correlated and clustered in the nine groups.
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ACKNOWLEDGMENTS The authors are indebted to the National Academy of Engineering for its financial support of a graduate student who pursued the data collection task. They are also grateful for the invaluable help of David Lee Han and Hans Seyffert, Jr., in collecting data and assisting with the production of the artwork.
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1985. Airport Activity Statistics of Certified Route Air Carriers for 12 Months Ending Dec.
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SAS Institute Inc.
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From page 49... ...
Personal income is the income received from all sources, measured before the deduction of income and other personal taxes but after the deduction of personal contributions for social security, government retirement, and other social insurance programs. Revenue All revenues except utility, liquor stores, and insurance trust revenues.
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, old-age Hospital Beds Beds, cribs, and pediatric bassinets regularly maintained for inpatients during a 12-month period. Library Books Major library holdings reported in terms of volumes per 1,000 persons.
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that support activities of certificated route air carriers. Departures All performed scheduled and nonscheduled departures.
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