Imagini ale paginilor
PDF
ePub

is emphasized by the fact that California serves as a gateway to the Pacific and, as such, experiences a high import/export rate across the State.

Figure 1 illustrates California viewed as a system. The State's major internal activities, or subsystems, are represented, with the broad arrows depicting the general flow of people, commodities, energy and information into and out of these major subsystems. The transportation activity, or subsystem, has been defined as carrying energy and information, since these flows are becoming increasingly important alternatives to the flow of mass. Overall control of the California system is performed by the governmental control activity or subsystem.

[merged small][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][merged small][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][merged small][merged small][ocr errors][ocr errors][merged small][merged small][ocr errors][ocr errors][merged small][ocr errors]

MARINO

Bisovea EXTRACTION

NOVINO

EDICAL

coduct

Culo

Hivias

FIGURE 1

Examination of this type of representation of California readily indicates two primary implications. One, the transportation subsystem is a central, vital element of the overall activity of California. As such, the functioning of the other major subsystems or elements is dependent upon transportation. Therefore, effective use of this subsystem can influence all other aspects of the State's growth and activities. Two, any analysis of the transportation subsystem must involve consideration of most of the other major State activities. It is there fore essential that an integrated model of the State of California be developed.

Volume III of this report contains the design for the integrated California transportation system model which will mathematically simulate the factual environment and reflect the socio-economic and technical interactions creating transportation requirements. Figure 2 shows the major submodels which in the aggregate comprise the transportation model.

[merged small][merged small][merged small][ocr errors][merged small][graphic][subsumed][merged small][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][ocr errors][subsumed][subsumed][subsumed][subsumed][subsumed][merged small]

Three basic submodels, Population, Econometric and Land Use, develop possible future transportation demands. These feed a fourth which is used to allocate demand to transportation modes and define the flow patterns. This information passes into a fifth submodel used to simulate existing or possible transportation systems and networks. The results of this simulation are fed into a sixth submodel for evaluation.

A data base is shown at the bottom of Figure 2, the contents of which are addressable by a high-speed computer. The information within this data base is that which is necessary to describe California physically and functionally in quantitative terms.

It should be noted that, within the operation of the model, the analysis pro ceeds incrementally: a projection of conditions at some future point in time is not made in a single step, but rather is reached through a progression of incremental time periods, chosen at will but usually representing five to ten years. This procedure permits the resolution of many problems which plague planning activities by producing the sequence of occurrences, allowing the point of divergence from desired results to be identified.

The Population Submodel activates and drives the entire California model through the development of population projections from the base year, 1963. An initial projection to the desired point in time is made for each of three non-overlapping entities : California, the rest of the United States, and the rest of the world. From a profile of expenditures by the projected populations, the demand for goods can be developed and is interpreted in terms of dollars distributed over sectors of the economy, including purchases of consumer goods produced by industrial sectors.

The demands discussed above form the driving functions for the Econometric Submodel, the heart of which is a rather complex analysis which accounts for interindustry activity. The objective is to establish the total output of every sector of the economy as well as the final fund flows between industries. The results of this analysis have many uses. For instance, productivity trends for each of the industrial sectors can be utilized to derive the labor force necessary to achieve the output required by the final demand. Any increment change in output is eventually utilized by the Land Use Submodel and converted into new requirements for land use. In addition, changes in the work force can be checked against the initially projected population growth and characteristics within the State.

Conversion of economic activity into land usage is the next step in the analysis, representing an interplay between the Econometric Submodel and the Land Use Submodel. This is done by allocating the increase in economic activity to basic land units or zones on the basis of relative attractiveness of the zone to the activity considered. In application, a descending order of priorities segments the land use: manufacturing, residential, retail and services, and finally wholesale locations.

The final product of the Land Use Submodel is the geographic specification of centroids of origins and destinations of personal trips and of those where commodity flows are generated (sources) and absorbed (sinks).

The analysis then proceeds to the development of the transportation demands generated by a given placement of people and other activities. This is done in two distinct elements, commodity flow and people flow.

Commodity flow is established on a yearly basis, adjusted for seasonal variations. Joint operation of the Land Use and Econometric Submodels allows all sources and sinks to be geographically situated and the total flow between them determined. Within the Transportation Demand Submodel, a market allocation process is applied to measure the flow between each source and sink. The result is the specification by commodity of the strength of desire, or demand, for flow.

The desire for personal travel is developed from information provided by the Population, Land Use and Econometric Submodels. The generation of desire to travel between zones is dependent upon the number of people and their economic status within the origin zone and the accessibility and attractiveness of the destination zone. The distance and/or cost of travel between zones is employed as a resistance factor.

Information derived from the Transportation Demand Submodel is fed into the Transportation Simulation Submodel, which simulates movement (the handling of the demand) over a transportation network. Initially, the transporta

tion demands for the year under study are applied to the transportation networks which exist or are firmly planned in the base year. This permits, for example, assessment of the growth potential of a given transportation link of an existing network, in terms of how long and well it will service future demands as influenced by several variable factors.

The Transportation Simulation Submodel furnishes information to the Evaluation Submodel describing the deficiencies, link overloads, revenues collected, etc., of alternative transportation networks. In turn, the Evaluation Submodel determines, through an iterative process, the network (mix of modes, routes) which should be applied to best serve the overall transportation demands and requirements of the periods under consideration. Technological changes related to new modes of transportation are reflected directly into network changes in the Transportation Simulation Submodel. In the iterative process, network changes are reflected back into the Population, Econometric and Land Use Submodels, with the principal effect being a change in attractiveness of the geographic zones with respect to their accessibility-one of the factors which determine the growth of a zone.

This then completes one major cycle through the submodels, resulting in a new description of the land use, population, economy and transportation networks which might exist at the time under consideration. The model can again be cycled in the same fashion to obtain other descriptions of the total California system for the same time period.

Other uses of the California Transportation Model are anticipated, one of which is to measure the impact of contingencies. For instance, changes in transportation demands induced by floods, earthquakes or fires are immediately reflected. In addition, technological advances likely to have a persuasive influence on the economy or on the distribution of the population would be incorporated in the Economic Submodel.

The development and use of the model(s) described will assist in finding solutions to the problems which transportation planners face, and will provide the means to assess and choose among several candidate networks and combinations of modes. Completely new modes of transportation, as well as improvements in existing modes, can be placed into competition with other projected services and their capabilities, convenience, feasibility, timeliness and cost compared. In addtion, simulations which project ahead 50 years can be employed to provide a measure of the future value or growth potential of any given network link or mode. This would be accomplished by holding the network constant while the rest of the model is allowed to project ahead several time cycles.

One useful exercise, typical of transportation-related problems which could be analyzed, would be specifying the location of people and industries within the State in a manner which would minimize transportation needs. While there is no mechanism which presently permits this exercise, experience obtained by running many options on the model would determine the sensitive cause-andeffect relationships, thereby guiding the selection of sequences and criteria for producing such a condition. The incorporated display devices would facilitate this process.

Quite apart from the transportation problems, there is much good to be derived from the broad structure, inherent exibility, and computer orientation of the designed study and planning device. It can serve to produce estimates of long-term effects on the land and economy caused by policy decisions at an earlier time. Within this same framework, it is possible to employ the independent projections by planning activities of the county, city or private sectors to gauge consistency with State plans and projections.

It is estimated that to construct and initially exercise the planning device described above will require approximately fifty-two months. Of course, the discrete submodels would be completed and operative at various intervals throughout this period, and could be utilized to analyze specific types of problems. The estimated schedule for the completion of the six submodels is as follows:

Basic Submodels:

1. Land Use: Developed and checked-out at the end of the tenth month. Can be used independently to investigate land-use trends and their attendant effects upon industrial and population distributions.

2. Population : Developed and checked-out at the end of the eleventh month. Can be used independently to investigate population growth and demand trends.

3. Econometric: Developed and checked-out at the end of the fifteenth month. Can be used independently to project interindustry flow, productivity and employment trends, and Gross State Product.

These basic submodels would be integrated with each other and with the data base at the end of the twenty-first month, and could be exercised to measure and project in a number of areas.

Transportation Submodels:

4. Transportation Simulation : Developed and checked-out at the end of the twenty-fifth month. Using independently generated inputs, can be used to assess adequacy of links by mode and to examine new or proposed transportation schemes.

5. Evaluation : Developed and checked-out at the end of the twenty-sixth month. Can be used to evaluate the outputs of the independently operated Transportation Simulation Submodel as well as the information generated by the simultaneous operation of the Population, Land Use and Econometric Submodels.

6. Transportation Demand : Developed and checked-out at the end of the twenty-ninth month. Serves as the bridge between the basic and transportation submodels.

All models would then need to be fully integrated and validated as a functional unit against an actual situation. This should be accomplished by the end of the forty-second month. Initial analyses on the validated model and final reporting are estimated to require an additional ten months.

More specific detail and explanation of the estimated schedule, manpower and management requirements and possible cost can be found in Volume V of this report.

CALIFORNIA TRANSPORTATION STUDY

BACKGROUND

or

On 17 November 1964, the State of California, Department of Public Works, Division of Highways, issued to the California aerospace industry a request for a proposal to design and develop specifications for an integrated study of transportation in California. Eighteen proposals were submitted on before 30 December 1964. North American Aviation's Los Angeles Division was selected, and the six-month study design effort began 15 March 1965. North American Aviation's assignment was to develop a work program indicating the content for a systems study of California's future integrated transportation requirements, including manpower, cost, schedule, methodology, data requirements, agency involvement, technology implications and an exhaustive statement of the transportation problem. The results of this effort are contained in a five-volume, 640-page report submitted to the State on 15 September 1965.

CONDUCT OF THE DESIGN STUDY The design study was conducted within the Los Angeles Division of North American Aviation. A cadre of specialists, drawn from North American Aviation's 30,000 degreed personnel from several of the divisions of the corporation, was assembled within the Los Angeles Division to conduct the effort. This basic team was supplemented and supported as required by additional personnel with unique qualifications. Fully fifty percent of these people hold advanced degrees in their disciplines, including five doctorates. Disciplines represented included: economics, mathematics, statistics, transportation, business administration, computer programming, operations analysis, systems analysis, data management, sociology, human factors, cost analysis, program planning and control, public administration, and various engineering disciplines.

No outside consultants were retained by the corporation. None were necessary : an ample inventory of qualified and willing professionals was found to exist within North American Aviation. Members of the study did consult with professional colleagues in universities, transportation and other public agencies, professional societies and private industry. Valuable assistance was obtained from these sources. Over 1500 documents, containing data and other information classified under 500 subject headings, were gathered from over 200 public and private groups.

A close working liaison with the State's Division of Highways and Advanced Planning Section, as well as with the U.S. Department of Commerce, Bureau of Public Roads (who cooperated with the State in this effort), was established and maintained throughout the study design effort. Direction and progress

« ÎnapoiContinuă »