Transportation and Urban Land

Lowdon Wingo Jr.

• Publisher: Routledge
• Year: 2016
• Topic: Economics
• eBook ISBN:
  9781317333340
• Subtopic: Environmental Economics
• Index: Economics

Urban land is a precious resource and originally published in 1961, Transportation and Urban Land aims to create an approach to analysing and projecting its uses with a particular focus on the household sector. By considering matters such as employment centres, organisation and technology of transportation and marginal valuation of residential space, Wingo develops a model to estimate how much land is required for residential land uses. This title will be of interest to students of Environmental Studies and professionals.

2

Characterizing Technology In Urban Transportation Systems

Transportation and Urban Spatial Organization

As the preceding chapter suggests, the central role in the model which this study will develop is played by the urban transportation system. The term “system” may connote a higher degree of organization and integration than is intended and should be viewed as referring simply to the total array of opportunities for the movement of persons and goods between points in the urban region. The system contains a number of more particular and more intricately organized subsystems—for example, transit systems, street systems (including the carriers that operate over them), and pedestrian systems, so that when the term “transportation system” is used herein, it is in this most general context and is specifically limited to the movement of persons within the urban region.

That the urban transportation system should be assigned this crucial role in a model whose purpose is to tell us something about the distribution of persons and the value of land in the urban region is certainly consistent with what we know about the impact of transportation innovation on the spatial organization of the city. In an across-the-board view of the larger American cities during the first thirty years (1920-50) of the “automobile age” it appears that the cities which grew the most during this period tend toward substantially lower gross densities than those whose major growth took place before the impact of the auto began to be felt (Figure 5). The 1960 Census of Population indicates not only that the population growth of the great metropolitan areas since 1950 has been absorbed by their suburbs, but that many of the central cities have been emptying out their populations into the surrounding hinterlands, a phenomenon facilitated by the great new urban expressways to serve the automobile and the rising real incomes extending the range of automobile ownership. We are literally surrounded by current evidence of these impacts; it is the specific nature of the impacts that is difficult to bring into focus.

The organizing role assigned to urban transportation has, of course, been central to the field of urban land economics for half a century. Richard Hurd’s classic Principles of City Land Values was published in 1903; in it he succinctly formulated the interrelationship of urban land values and the urban transportation system, a proposition scarcely modified in current writing on the problem.¹ The pioneering works of Weber and von Thünen² in the economics of location similarly brought transportation to the fore as the distributor of economic activities over the landscape; their positions have recently been extended and amplified by such students of locational economics as Lösch, Isard, and Dunn.³ And so it is that transportation has become a primary element in the theories about how economic activities get distributed on the one hand and land values are developed on the other.

Our initial task is to determine what features of urban transportation are essential to the problem of understanding how households get distributed within the metropolis, how these features relate to other crucial aspects of urban organization, and how the relationships can be made into quantitative statements to be manipulated. We begin with the proposition that the relevant characteristics of the urban transportation system can be summed up in the cost characteristics of the system. This requires that the unit of transportation services be identified, that the kinds of cost relevant to the problem be delineated, and that the processes by which these costs develop be described. This chapter will concern itself with the cost characteristics of the time spent by persons using urban transportation systems.

FIGURE 5. Scattergram of 45 U.S. cities having (1) a population of 200,00 or more in 1950, and (2) a positive population growth during the period 1920–50 (relating index of growth, 1920 = 1, to population density of urbanized area in 1950).

Source: U.S. Census of Population, 1950, Vol. I, Part 2: Growth, pp. 46–47, Table 23; Density, pp. 26–29, Table 17.

The Role of Accessibility

A parcel of “land” has two characteristics of interest to the economist: (1) a natural endowment, such as a class of soil, a mineral content, or water, for which society, given its technology and its wants, may have use; and (2) a quality of location with respect to the array of economic activities. The economic role of the endowment of urban land is generally confined to those topographical and geological features which affect its usefulness as site, or which condition the amount of “plant capital” necessary to bring it into a specified use. The quality of location, or “accessibility,” is the dominant factor in determining the uses of the land and their intensity.

In a technical sense, accessibility is a relative quality accruing to a parcel of land by virtue of its relationship to a transportation system operating at some specified level of service. For purposes of an economic analysis this quality can be measured as the sum of the reciprocals of a specifically designated set of transportation costs associated with the parcel.⁴ The “level of service” of a system should be distinguished from its “quality,” which connotes a “level of amenity:” riding to work in a chauffeur-driven Cadillac as compared to car-pooling in an old Ford is using transportation of superior quality but not necessarily of a higher level of service, especially if both observe traffic regulations and endure the same traffic congestion en route. For our purposes the level of service of a transportation system is a reflection of the quantity of transportation services supplied by the system and the volume of demand that is asserted upon it: it is, in short, a measure of the system’s efficiency, its “output” per unit cost. To build into a model the element of accessibility requires some analysis of the determinants of the level of service—the demand for and the supply of the services of transportation.⁵ Later the “level of service” will be translated into a set of costs and hence, indirectly, into accessibility. From this point it is but a brief step to the principal problem—the intraurban distribution of households and land values.

The first step is to identify the “unit of output” of a transportation system. In fact, there is no single unit, and the unit chosen will vary with the purpose of analysis: the number of person-trips per period⁶ is a useful measure of capacity; passenger- (or ton-) miles are an effective engineering measure for the output of a system; the simple aggregate of person-trips is an important measure of output when certain kinds of structural regularity are being sought in the data. Transportation yields a product which has three basic dimensions—volume, time, and space—and so it can be measured in different ways.

Take the case of the businessman in a large city who drives five miles to work on a Monday morning. At the most general level he has made one of several million person-trips made on that morning. Put in a time dimension, he ended his trip at approximately the same time that several hundred thousand other residents ended theirs, and so he was a part of the morning “peak flow.” Put in a space dimension, he followed a route which was one of a limited number of reasonable alternatives that existed for him because of the manner in which the street system is laid out. Joining both time and space dimensions, we can see how his delay in a traffic jam resulted from the fact that a large number of other drivers were seeking to occupy the same space he was occupying at the same time that he was occupying it, and how accordingly his average velocity fell to only fifteen miles per hour compared to his normal twenty. It is apparent that the nature of the analysis will determine which of the dimensions of the unit are relevant and which can be held constant.

Concepts of Transportation Demand

The “demand for transportation services” is the number of units of output which will be consumed at various levels of “cost.” Because the unit of output has several dimensions, the demand for these services has several meanings also. Each concept of demand involves different conditions and responds to different variables: the conditions determining how many trips people will want to make are quite different from those determining how many people will want to shop downtown on Thursday morning. Five different concepts of transportation demand in urban systems can be identified and labeled: the “demand for movement” is concerned only with the aggregate number of trips that people in a given urban area will want to make; “traffic demand” is concerned with the number of trips in terms of their spatial characteristics; “load” deals with the distribution of trips in time; “flow demand” relates to the number of units that want to pass a specified point at a specified time; and where that point is the common destination for a number of trip movements, we will speak of “deadline demand.”

“Movement demand” can best be understood in a purposive framework. People make trips between locations to engage in transactions of one sort or another, and the basic purpose of a transportation system is to facilitate the assembly of persons engaged in those transactions.⁷ They may be simple money transactions involving the purchase of goods and services, or they may involve the exchange of labor for wages, as in the journey-to-work, or they may be transactions of a more personal sort, such as participating in a social or recreational experience, but virtually all movement is carried out for specific s...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Original Copyright Page
• Table of Contents
• I Introduction
• II Characterizing Technology in Urban Transportation Systems
• III The Economics of the Journey-to-Work
• IV Economic Dimensions of Urban Space
• V The Demand for Space and the Basic Model
• VI Applications of the Model
• Summary and Index of Important Expressions and Equations
• Appendix A A Further Note on Ingression and Congestion Along Transportation Routes
• Appendix B The Mathematics of Ingression