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Climate projections in many U.S. metropolitan areas show increases in daily temperature, and potential shifts in rainfall patterns toward stronger, more intense storms. At the same time, metropolitan regions continuing to experience population growth face the prospect of areal expansion and higher land-use intensities. The possible coupling of such developmental changes and more frequent intense precipitation events poses a litany of well-known challenges to storm-water management. This paper reports survey research that examines the experiences and expectations of engineers, planners, and other agency staff in storm-water management in the Washington-Baltimore metropolitan region in the context of climate change. We find that staff from jurisdictions with a high degree of development and strong population growth, and those with more work experience, engagement with climate issues in their work, and greater belief that scientists understand climate change, exhibit a higher level of concern with th...

This paper provides, for the first time, an insight into the influence of urban, political, demographic, and economic factors on several categories of municipal spending, after controlling for the spatial effects. The models of spatial two-step least squares (S2SLS), spatial lag, and spatial error are applied to a sample of 3,204 Spanish municipalities for the year 2005. The results show that the spending of a municipality is influenced by its neighboring municipalities’ spending. Concerning geographical factors, population density has a negative impact on municipal expenditures per capita. The negative impact of population density on per capita total expenditures has policy relevance because it indicates that planning decisions aiming at increase population density will reduce per capita government expenditures, both in small and larger cities. Political ideology does not influence spending. Nevertheless, strong political governments do spend more. Therefore, it is not that the incumbents belong ...

The writers created a new approach to evaluate environmental performance factors and measure the current or past environmental performances from various city and exurban by aggregation steps. Defined environmental resource indices concerning natural resources development, physical environments, population, economical, and social structures were complex and appeared related to location. The writers conducted a nationwide questionnaire survey to evaluate the entire environmental performance, and give conclusions to urge central and local officials how to detect their most urgent environmental issues. A case study in Taiwan illustrates the usefulness of this approach. This study contributes to the resource management by collecting and analyzing current and past environmental performance that provides a better understanding of the empirical cases toward environmental targets.

A sprawling U.S. population continues to spread into the fringes of urban development placing both populations and property in areas that were once largely unoccupied. Population tallies, housing unit totals, and housing values for 1990 and 2000 are examined to determine the extent to which this growth has affected the tornado hazard in northeastern Illinois. The growing town of Plainfield, Ill., located southwest of Chicago, is examined to determine how vulnerability to a tornado impact has changed in the town since an F5 tornado struck the community in 1990. The population and housing data indicate an increase of 8,629 persons and 3,058 housing units affected if the tornado were to have occurred in 2000 rather than 1990. Estimations of housing value affected by the Plainfield tornado indicate a 50% increase in 2000 compared with 1990 values. In addition to studying the impacts on Plainfield, four other scenarios are examined in suburban Chicago counties using the 1990 Plainfield tornado as a model for a potentially devastating strike. The large increase in total value of homes affected for each scenario highlights the overall increase in wealth throughout the study area, specifically along the urban fringe of development. The physical vulnerability throughout the study area has increased with the rise in population, but the most socially vulnerable areas appear to remain in the older urban centers.

The transformation of the planned housing provision as an in-kind welfare benefit to a market-oriented housing allocation system is the ultimate goal of the urban housing reform in China. The main concern of the housing reform is to regulate the relationship between the state, market, work units, and individuals. Housing has always been a major problem in Shanghai. The rate of new housing construction has lagged far behind the rate of population growth. In the market reform process, the state has been reducing its role in housing provision which has resulted in significant increases in house prices as well as demand for housing at an affordable level. There is a gap between housing price and affordability. This paper examines the different measures of urban housing reform toward housing affordability in relation to the different stages of economic development in Shanghai during the periods from the 1980s to now. It emphasizes the rent policy and the “provident fund for housing”—A housing saving scheme. Th...

The U.S. Census Bureau estimates that one in four persons in the United States will be of Hispanic origin by 2050, up from one in eight in 2002. Driven by immigration, this dramatic growth in the Hispanic population will present unique challenges in the workplace. In construction, the increase in the Hispanic population has enabled the industry to meet its workforce demands. Unfortunately, this has occurred with costs in the health and safety of Hispanic construction workers. Using data from the U.S. Bureau of Labor Statistics' current population survey, current employment survey, survey of occupational injuries and illnesses, and census of fatal occupational injuries, this study examines relative differences in injuries, illnesses, and fatalities between Hispanic and non-Hispanic construction workers by occupation. The findings show that differences in injuries, illnesses, and fatalities exist between Hispanic and non-Hispanic construction workers, although not always unfavorably toward Hispanics, and the difference does vary by occupation. The implication of the increasing size of the Hispanic construction workforce with respect to construction safety and health training needs is discussed.

Road transport networks that exist within Eastern Asia are experiencing ever-increasing levels of demand due to rapid population growth within the region. This is especially so for interregional travel because of a continuous dispersion of the population as it expands. Within Hong Kong, new transport infrastructure is required to cater to the demands emerging from growth and decentralization of the population distribution. Initiatives such as park-and-ride schemes can assist transport networks to operate more efficiently and are worthy of assessment as a demand management technique for inclusion in the future transit system. As a result of a comprehensive survey conducted on a trial park-and-ride facility in Hong Kong, lessons have been learned for the implementation of future schemes within Hong Kong and Eastern Asia. This paper provides a description of the data assembled as a result of the survey, and it identifies reasons and factors contributing to the success of the park-and-ride facility in Hong Kong.

The United Nations forecasts a world population growth of 1 billion in the next decade and 2 billion in the next two decades-growth that will place immense demands on the developing nations' water resources. The extent of these demands when placed against the constraints of time, water, and funds, and the lack of plans to manage droughts confirm that the world faces a serious water crisis. Yet, most actions proposed in today's debate offer questionable solutions, many built on faulty assumptions. Water markets and increases in irrigation efficiency will do little to meet the needs of these countries. Reallocations will have far-reaching social repercussions. The time constraints dictate that the situation be addressed with a greater sense of urgency and that proven measures, even if controversial, should be promptly implemented, while studies should concen­ trate on approaches that can realistically offer significant help in the following decades. An example of the consequences of the international community's confined if not distorted perspectives is offered by a case study of India's Sardar Sarovar Project.

The challenges posed to the engineering profession by population growth and information technology will, it is argued, call for leadership and an ability to communicate effectively. Drawing on his experiences as a member of a team that sought to assess the condition of infrastructure in lower Manhattan in the days after the September 11 terrorist attacks, the author recounts the difficulties encountered in gaining access to certain information. It is vitally important for political leaders to ensure that the public knows whether or not the engineering community is providing the technical assistance and expertise required during an emergency. This may, iti is argued, call for better coordination of the efforts undertaken by political leaders and leaders of the engineering community. As part of their professional ethics and concern for the welfare of society, engineers should effectively communicate to the public that they are there to help ensure safety.

The availability of a water supply does not determine the population growth or land use that will be supported by that supply. Water needs vary between uses and water may be reallocated from one use to another. The same amount of water needed to serve a low population at low densities will support a larger population at a higher density due to reduced outdoor use. A reallocation of water from agricultural to domestic and industrial use permits a greater population. Therefore it is not the availability of water supply or lack thereof that permits or constrains growth but rather the political decisions by cities and counties related to economics, social factors, and land use. Analysis shows that land-use projections represent a more reliable basis than population for the determination of future supplemental water requirements and the design of water distribution systems.

Faced with a probable decline in its historic role of developing irrigation in the West, a new role is hypothesized for the U.S. Bureau of Reclamation. This role is in planning for other types of economic growth that will draw additional population to the West and cause the growth there of new population centers. The causes of a probable decline in subsidized irrigation, the rationale for encouraging future population growth to occur in the West rather than in the East, the means of such growth, and the types of impacts that would have to be analyzed are considered. This new planning role for the Bureau is seen as one way of utilizing the Bureau’s capability.

California is undergoing massive population growth. Accompanying this growth is a need for affordable housing. Unfortunately, housing costs are still out of reach for many Californians. To these people, the American dream of home ownership is and will always be simply a dream. Even rental costs lie outside the reach of many individuals. This article examines the way in which California, in general, and San Diego County municipalities, in particular, are reacting to changes in the housing market and to the pressing need for more rental housing. Allowing second units in single-family or multifamily residential zones offers one way of providing affordable rental housing to some segments of the population.

Analysis of data from approx 15 origin-destination studies in a population range of 20,000 - 500,000 was performed to develop, through the use of factor analysis and regression-correlation techniques, a number of simplistic models that quantify the number of various types of trips in various types of vehicles by various users relative to definable attributes of the urban areas (i.e., population, car ownership, etc.). The purpose of the development of the models is to allow the transportation planner the opportunity to quantify estimated gross trip numbers in his community by purpose and mode in a relatively easy manner with the expectation that the predicted values achieved will be within a reasonable degree of accuracy to the actual value that will occur.

Since no totally environmentally-clean forms of energy sources are available, our exponential growth in energy requirements has precipitated related pollution problems. Population growth has certainly been a major factor in this increase, but a more critical factor has been the per capita increase in energy use, so much so that a recent U.S. study attributes only 20% of the increase to population growth and the remainder, 80%, to increased use per individual. These developments have created a difficult dichotomy. On one hand, after decades of sustained growth, our current energy requirements are increasing at an even faster rate than in the past, and on the other we are intensely concerned with protecting the environment from the deterioration which the development, distribution, and use of energy can create.

An econometric model is developed to forecast the impacts of alternative future scenarios on the Virginia Division of Motor Vehicle revenue potentials. The model consists of 12 basic components, the major components being population and economy. The tested scenarios relate to possible social, political, economic and demographic future conditions, such as, high price of gasoline, President Carter's energy proposal, persons per household, shifts in population density, the impact of Virginia's participation in the International Truck Registration Plan (IRP), etc. The results, in general, show that gasoline tax and sales and use tax revenues will decline under adverse economic conditions, while registration fee revenues will remain fairly stable under most scenarios.

The 1980’s will face a paradox of urban growth and decline in many areas throughout the United States. Recent U.S. Bureau of Census estimates and other observations reveal that since the 1970 census, dramatic shifts in population distribution patterns are taking place, reflecting a reversal of past urbanization trends towards fewer and larger metropolitan regions. While older central cities continue to face declining population and economic bases, expanding urban growth to nonmetropolitan areas and smaller cities unprepared to accommodate rapid growth pose numerous challenges to provide the necessary facilities with increasingly limited resources.

The professed goal of World Health Organization—to supply potable water to the poorest of the poor in the developing countries by the year 1990—appears to be quite an optimistic one in view of the existing situation in the developing countries, where potable water is still out of the reach of 80% of the populace. Supplying potable water to the rural population in these countries is quite a gigantic task owing to lack of physical and institutional resources. Any major effort at providing safe potable water to rural populations should first aim at improvement of the small community water supply systems. Small community water supply systems in these countries generally include: (1) Groundwater supplies; (2) rain water storage basins; and (3) surface water storage basins. Existing technologies of small community water supply systems in Indonesia and India are discussed and recommendations are made for improving their technical performance to meet the professed United Nations potable water supply goals.

The common practice of classifying cities into large, medium, and small population sizes, while appealing at first sight, is not adequate for travel forecasting. Two large cities with similar population sizes, for example, may turn out to have drastically different urban structures, thus generating totally different travel patterns. A more refined classification scheme involving both urban size and structure is therefore discussed in this paper. Person-trip-hours-of-travel -- as determined by the product of trip frequency and trip duration -- is used as a classification criterion, since trip frequency measures the rate of trip-making while trip duration indicates the length of the journey. According to this scheme, a city is either identified as large/multinucleated, large/core-concentrated, medium/multinucleated, or medium/core-concentrated. The validity of such a taxonomy is tested and proven by the data compiled from over 50% of the cities in the United States.

The trend in transit operations is toward public ownership and operation of services. The only questions are: when, how, and how much. The trend in public operations is to establish regional authorities or taxing districts with a provision of service to the urbanized area and to proportion taxes to the population served. Comparative statistics indicate that: (1) large transit systems have fleets of reasonable age regardless of ownership; (2) smaller systems show private systems having fleets over 15 yr of age, and public operations with average fleet ages under 7 yr; (3) private systems provide service more efficiently than public operations with number of passengers carried per vehicle mile at 3.32 for private systems compared with 2.91 for public operations; (4) the number of annual transit rides per capital is higher for private systems (40.1 vs. 34.2); (5) private systems have more employees per unit of service and per vehicle owned; and (6) private systems are more productive in terms of the number of passengers served.

Almost any type of planning requires a population forecast. Migration is one of three components of population change—fertility, mortality, and migration. Several attempts have been made to establish meaningful relationship between socioeconomic and migration data. These attempts include Zipf's interactance model; Stouffer's intervening opportunities model; Somermeijer's, Lowry's, and Schwind's gravity models with attraction indices; Blanco-Lowry population change due to migration models; Ichimura's and Muth's econometric models; Forrester's Urban Dynamics model; and mobility behavioral models. Comparison and critique of these models have shown that econometric models and Blanco-Lowry models of population change due to migration are the most useful to planners. Econometric models require a level of cost and expertise not commonly found in most planning agencies. At their present state of development, mobility models are of little or no help to planners in terms of population forecasts. Migration models show promise of eventually becoming truly useful in connection with regional population forecasts.

The research objectives of the BART Impact Program Land Use and Urban Development Project are summarized, and the results of studies of BART's accessibility impacts and their importance in explaining: (1)Regional shifts in employment and population; and (2)BART's effects on the office construction and housing industries are presented. A preliminary analysis of regional trends since 1950 indicates that BART has not measurably affected population and employment growth within the corridors it serves. Changes in the office construction and housing industries within the three-county BART service area are covered, and BART's role in timing and location decisions is analyzed. Topics yet to be addressed in the research project are highlighted and the implications of these preliminary findings are described.

Recent decades have witnessed an exponential growth in the size and complexity of planning and transportation models. Associated with these model building activities has been the desire to accurately forecast demand, which in turn, involved complex predictions of population, income, land use, and a variety of variables, all of which affect future use of engineered facilities. The degree of attempted sophistication of these modeling activities has frequently been at odds with the accuracy or reliability of the given data or with the final use of the results. Less sophisticated procedures that are transparent (intuitively obvious) to a wide range of community participants are needed, and they must be based upon an understanding of how accurate we need to be.

The engineering profession is shown to be under continuous challenge from neo-Ludditism, and its mistakes, which were without guilt, are being used to adversely influence public opinion. Engineers today need expanding knowledge in the social and behavioral sciences to be able to meet their expanding responsibilities. The future for civil engineering is examined in detail for impacts from zero population growth, the computer revolution, narrow technical decisions, mass education, and the nation's economic outlook: it is shown that civil engineers might well devote more of their energies to developing skills in public policy.

This paper is based on the results of a Federal Highway Administration study to reevaluate national highway travel forecasts in light of such factors as declining birth rates, possible saturation of vehicle ownership, and fuel constraints. Results indicate that highway travel is expected to increase at an annual compound rate of 2%/yr - 3%/yr to 1990 as compared to an average annual growth of 4.6% for the last 20 yr. The travel projections are based on anticipated increases in population, licensed drivers, vehicles, and personal income. Even with fairly severe constraints on fuel the travel projections appear reasonable, assuming continued increases in the fuel efficiency of the vehicle fleet using presently available technology. Although this was a national assessment, review and application of these analyses at the state and local level are encouraged.

This study attempts to develop mathematical models that will adequately synthesize through trip travel patterns in small urban areas. For urban areas below a population of 50,000, utilizing the results of this study with current techniques of synthesizing internal travel patterns, the need for the costly and time-consuming origin-destination survey is obviated. Based on common statistical measures of accuracy, the procedure presented in this paper appears adequate for transportation planning purposes.

A new method for predicting long-range water demands was developed to quantify the post-drought effectiveness of water conservation in the San Francisco Bay Area. The method used general relations between water use and population density, and employee density that were derived for the Bay Area. Several alternative water conservation programs were tested using the projection model and the resulting water savings ranged from 4% to 16% by the year 2000. The costs of water conservation were compared with those for building new water supply projects. It was concluded that water conservation was more cost-effective than other sources of water supply.

Recently there has been an increase in the number of regional water supply systems in the Midwest. These systems often serve large livestock populations in addition to the domestic needs within the region. Peak use periods in a rural water supply system with large livestock populations are longer than those seen in high density residential areas. The increased length of peak use can be attributed to livestock feeding operations, but it is not possible to distinguish between the domestic and livestock influences at any particular time. Peak rates of use were found to occur between 7 a.m. and 11 a.m. and 4:30 p.m. and 8:30 p.m. The nomographs indicating daily livestock water consumption developed from data collected in the literature appear to give reasonable predictions of livestock water requirements based on animal weight and average environmental temperature.

The urban carless population, those members of the metropolitan community who lack access to an automobile, may be considered as a distinct population subgroup with common mobility attributes and mobility problems. The mobility restrictions of the carless are divided into two major categories: (1)Trip-making constraints which are related to the inability of the carless to generate a vehicular trip; and (2) environmental constraints which are imposed on carless groups by the physical and social environments in which they live. The conceptual framework is applied to a particular study area on the periphery of the Denver Central Business District. Descriptive profiles of the socioeconomic and travel characteristics of the study area as well as the rest of the Denver metropolitan area are developed. The difference in travel behavior between the carless population and other members of the metropolitan community are not a reflection of different tastes or preferences, but rather, a result of their restricted mobility. Language: en

It becomes increasingly obvious that the number of minorities and women in engineering is far below any reasonable proportion to their percentage in our population, and recent statistical data do not reflect any substantive revision to these proportions. It is also very obvious that the shifting of minority individuals and women from one company to another to fulfill the new company's Affirmative Action Goals is of no real help to anyone and definitely not an acceptable or lasting method of remedying this situation. Recognizing the soundness of the human relation principles involved and because of firm adherence to our belief in the correctness of a policy which endeavors to attain the maximum utilization of the potential of all the people of our country, the (name of company) without reservations or restrictions endorses and adopts the following Affirmative Action Plan.

The variety of roles played by an urban dweller, and the fact that such roles are often played at different points in geographical space, render it likely that social impacts of an urban highway project are not all confined within a narrow transportation corridor. Residential relocation in particular may affect widespread portions of an urban area. Social status considerations are important factors in location decisions by highway relocatees and other homeseekers. A residential location model based on social status is presented and tested against census data for the Toledo, Ohio SMSA. The model is then applied to a set of three hypothetical freeway locations to show the change in the geographical distributions of various social indicators, including total population, non-white populations, and housing vacancies. It is concluded that the proposed model provides a useful tool for quantitative study of social impacts outside a transportation corridor.

An investigation is made on the nature of impacts of public investment in a Light Rail Rapid Transit System in Buffalo, New York. In particular, the impact of the public investment is measured against population and employment declines that have occurred in the region in the last ten years. By assuming that the investment in rail is justified by more than the usual travel measures, associated redevelopment trends in the CBD, the focus of the transit development, are noted. While regional employment declines, service-oriented employment increases. This increase coupled with an increase in the number of women in the labor force, and increases in household income make private investment in the CBD more attractive. New construction, related to these trends (offices, hotels, retail space) has begun, reinforcing the transit decision.

The interrelation of the major problems facing the world — population, food, energy, and raw materials — is examined. The magnitude of these problems vary widely from nation to nation. Unable to cope with four billion people, the world is anticipating nearly three billion more by the end of the century. Urban regions are at present growing at twice the rate of the overall population growth. The best indication that certain areas of the globe are already overpopulated in terms of their resources and development is the present world hunger. The task of more than doubling world food production by the end of the century presents great difficulties. Even if we produce enough food, there remains the problem of distribution. Increasing energy requirements and the recent increase in energy prices affected the developing nations even more adversely than the developed nations. These crises have led to a debate on the possible ultimate limits.

The problem of wastewater treatment plant capacity is examined. A decision model, which utilizes a dynamic programming formulation, is developed which generates optimum plant capacity expansion strategies. The model allows for variation in available treatment technology, capital and operating costs, demand based on different population projections, and changes in construction and labor cost indices. The methodology of the model is in such form as to be readily usable by managers and decision makers interested in exploring short-term or long-term plant expansion programs. Comparison with other research on capacity expansion is made and the model is found consistent with previous theoretical results.

Used cautiously, fisheries statistics can be invaluable to sanitary engineer in evaluating claims that waste discharges are responsible for declining or fluctuating fisheries resources; after describing types of data encountered (catch, catch per unit of effort, actual populations, time of occurrence), proper and improper uses of statistics are shown in 9 illustrations.

Unit costs of construction and maintenance of municipal public works and public utilities are a function of residential neighborhood population density. There has been a need for cost data on such municipal improvements for single-family residential neighborhoods to assist planners and engineers in setting planning and design standards for various development densities and in evaluating the costs of developing urban areas at varying densities. The investigation developed some of the needed information by means of a field study of expenditures for construction and maintenance in four residential communities and by synthesizing data for a hypothetical residential neighborhood. An account of the sources of field data is given. The manner of defining and determining residential population density is described. Some results of the data analysis for sanitary sewerage and water lines are presented as a series of 15 graphs with textural references and interpretations.

A method for stochastic population projection for small areas is developed for use by consulting engineers as a basis for specifying the design capacity of pollution control facilities. Based on the components-of-change model for population growth and a formulation of demographic rates as first-order autoregressive processes, the proposed projection model specifies future population in terms of a probability distribution. Monte Carlo simulation rather than analytical solution is used to derive the probabilities. An analysis of the first results suggests a significant improvement in predictive accuracy over the traditional subjective or deterministic projection models still in widespread use by the environmental engineering profession.

Chicago was the first city to apply the concept of integrated use of a right-of-way for both expressway and rapid transit, but actually the concept of a multimodal transportation corridor is an old one. The basic need for multimodal use of transportation corridors arises from the cost and difficulty of assembling right-of-way. As the world's urban population grows at explosive rates, the sheer scarcity of land looms as a factor of growing importance in the making of all policy. Giving up land for urgently needed new transportation corridors becomes increasingly objectionable at any price in this era of increasing social awareness. Combined use of rights-of-way lessens these objections by offering offsetting advantages to more people and by utilizing land more efficiently. The paper describes applications of expressway transit presently operating or planned.

Foreign standards are not suitable for determining the nominal size of water treatment plants in Colombia. An analysis is presented on the basis of a survey of Colombian treatment plants. A new formula is derived of plant capacity depending on population of the city, and four coefficients for gaging plant operation are determined.

The paper points out the problems created in the fields of water supply and sewerage by the post-war population boom. The manner in which the problem was studied and the observations that were made are exmained.

Application of probability theory provides a rational and systematic approach to the problem of reliability prediction of such basic planning input data as population and economic forecasts. Furthermore, Bayesian decision statistics permit the utilization of a quantitative method for determining the best possible planning decisions with available information and planners' past experience and judgement. In this study the concept of reliability in land use-transportation planning is examined. As an example, the problem of county-level population forecasting in the southeastern Wisconsin region is considered. The reliability values associated with the population projections generated by different methods and for various counties are established. Also examined are the optimal number of different sets of projections to be considered for a county. The procedure outlined here can assist planners to arrive at an optimum level of design year population based on economic considerations, past experience and the amount and nature of information available.

Changes in a number of metropolitan areas (Standard Metropolitan Statistical Areas), SMSAs with and without belt highways before and after highway construction lend little support to fears that these beltways may affect downtown areas adversely. Also, right-of-way acquisition has little, if any, bad effect on tax rolls. A comparison of the 1950 to 1970 changes in seven beltway SMSA with seven matched nonbeltway SMSA indicates beltway areas: (1) gained more population; (2) lost less central city population; (3) had more land urbanized; and (4) gained faster in total employment and in office space than control areas. Beltway areas also gained in retail sales in central cities and central business districts (CBD) more than did nonbeltway areas from 1958 to 1967. Initial losses in tax rolls from right-of-way acquisition may be offset by gains from development attracted to highway locations. In some cases, these offsetting gains in tax rolls occur while right-of-way is being acquired.

Study of relative effectiveness of various areal characteristics as predictors of one specific type of travel, automobile trip to central business district; series of regression equations relating total, shopping and business-work trips to vehicle registration, population, residential density, dwelling density, vehicle density, and distance; reliability of predicting factor or factors is tested and computed and actual values are compared.

One feature of the 1968 Illinois Water Plan was concern with the condition and future capability of water systems in 1200 incorporated communities. It was necessary to determine the condition of each water facility, such as its present pumpage, the filter plant capacity, and the water source capacity. Projections of the water demands on each system to the year 1980, and on a county basis to 2020, were made by using population estimates. By developing a gallons per capita per day relationship from present pumpage and present population data, corresponding 1980 values could be computed by using the appropriate projected population data. The technique for presenting these data is shown in both graphical and formula form. In addition, table sand graphs are included to show various parameter relationships and how the large amount of data were assembled in order to display projections individually, by counties, and by river basins. This water resource planning approach has a potential for wide use beyond the area for which it was developed.

To prepare plans for future development of the Philadelphia International Airport, forecasts were made to 1985. These were based on analyses of historic trends, economic factors, forecasts of population and business growth, and checked against forecasts by the airlines. Domestic passengers are expected to increase from 3,600,000 in 1965 to 12,200,000 in 20 yr; international passengers from 67,000 to 600,000 and air cargo from 84,000 tons to 1,400,000 tons. Aircraft loading positions for passengers are predicted to increase from 28 to 66 in 1985, while 30 cargo loading positions are expected to be necessary in 1985. The forecast shows a need for over 12,000 public parking spaces for private cars. Airline aircraft movements totalling 140,000 in 1965 are expected to double in the forecast period.

Interference of population and urban growth with flood protection; review of TVA experience in identifying flood danger areas of cities and encouraging local action to guide urban development away from these areas.

In the words of the demographers, the world’s population is "exploding." If present growth rates continue to the year 2000, the population of the United States will have increased approximately 1.82 times. Communist China 2.16 times, and other areas of the world by like amounts. It is estimated that by the year 2000 the United States will be producing approximately one-third more food than needed for its own people, while Communist China and much of the rest of the world will be producing less than one-half the food needed. Under those circumstances mass starvation would be inevitable. Civil engineers must accept the responsibility for making the cultivated lands yield most efficiently through proper irrigation and drainage, particularly in the humid areas of the world.

This paper uses the wastewater collection utility to demonstrate the need and possibility of developing a normative mathematical relationship between the cost of installing such a utility on the one hand and the area being served and population density on the other. On the basis of an analysis of optimal network designs which were obtained by the use of a nonlinear programming algorithm, diseconomies of scale exist with increasing network size. This implies that a number of smaller and simpler networks may be constructed at a greater economy than a large enveloping system and treatment plant size. The combination of these factors—the network costs and the treatment costs—indicates that a minimum per capita cost solution exists. The size of the system at which a minimum cost is obtained is highly sensitive to the density of the population in the area being served but is relatively insensitive to the size of the service area.

The writers have pointed out the emerging water resources problems associated with the escalation of the nation’s life style and population growth made possible by unprecedented technological capability. The importance of shear magnitude and short response time as well as an evident shift of emphasis from an open loop to a closed loop system was also stressed. Engineering has accepted the necessity of advance planning and exploration of alternates using the systems approach looking at possible and probable worlds. Comprehensive systems with roots firmly grounded in the future are required to meet the needs before they present themselves, freeing the engineer from historic and rigid laws. The Riparian and appropriation doctrines are all found wanting, and based on a Res Communes doctrine legislative law is suggested that will provide for operation and management of water resources system in an optimal fashion, permitting engineers, economists, and lawyers to work together placing technological and ecological priorities in their proper perspective. Such a system would protect long-term investment, enable long-range planning and establish alternative goals.

This paper continues studies of the Southwest Pennsylvania Planning Commission. On the basis of examples on regional and national population concentration, it is evident that urban growth can and does become malignant, when permitted to continue without limit. Two conclusions are apparent: (1) Irresponsible expansion of facilities and services beyond a certain land-use saturation limit actually abets and sustains urban growth; and (2) the corollary that intelligent environmental design is possible only when it is prefaced by the determination of the ultimate land-use saturation limits. Traffic congestion is the most significant source of urban air pollution today: It is another unfortunate manifestation of the urban growth syndrome. Population management and transportation management go hand-in-hand as basic elements in urban design.