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described, and three new morphological edge opera- tors have been developed. The new edge operators have been applied on test patterns to measure their performance and effectiveness. A tentative hardware implementation of the Morphological Edge Detec- tors developed has been presented suited for possible future implementation as semi-customized VLSI chips.

The second aspect of the research describes a data compression technique based on the combination of three independent data compression techniques. The technique described is unique in the manner in which three very simple compression techniques have been combined to result in a compression technique capa- ble of compressing a digital picture by a factor of 1 : 15. Finally, a tentative approach for implement- ing the compression algorithm in hardware is pre- sented. The main attraction of the hardware imple- mentation is its simplicity.

TRAFFIC ASSIGNMENT AND TRIP DISTRIBUTION

A combined trip distribution and assignment model with dogit destination functions. Chu, You-Lian. University of Pennsylvania, 1989. 171 pp. Supervisor: Tony E. Smith.

Order Number DA9015076

Most of the previous literature on the subject of the combined trip distribution and assignment problems has focused on the logit and entropy distribution models. While these types of models are satisfactory for many applications, they are incapable of han- dling situations where the observed trip patterns are represented by both compulsory (captive) and discre- tionary (free) travel behavior. Consequently, this pa- per suggests the need for using a dogit distribution formula in the construction of a combined trip distri- bution and assignment model.

We will show that the proposed combined model can itself be reformulated as an equivalent convex mathematical program so that the equilibrium condi- tions on the network, and the dogit destination de- mand functions, can be derived as the Kuhn-Tucker conditions of the proposed program. After this dis- cussion, existence and uniqueness are presented, and solution algorithms for the combined model are stated. In addition, various issues relating to the cali- bration of the combined model in the cases of the availability and absence of equilibrium travel cost data are discussed. Finally, numerical examples are illustrated, and a discussion comparing some as- pects of our model with other existing models is in- cluded.

Recent Doctoral Dissertations

TRANSPORTATION AND ECONOMIC DEVELOPMENT

Commercial activities and the geography of movement in a West African urban market: A study of market-stall traders in Onitsha with implications for transport policy. Ochia, Krys Chukwuma. Portland State University, 1989. 212

pP. Order Number DA9105824

The purpose of this study is to understand the non- home-based travel behavior of urban market traders in Onitsha, Nigeria, where 58070-70070 of the labor force is engaged in trading. Relevant trip-inducing var iables-gender , location, means of personal transportation, size of stall, and type of good s o l d - were selected to assist in theorizing about the travel behavior of traders. Using a systematic sampling methodology, 246 stalls were selected and the MLR model was applied in data analyses.

The results show that a typical stall is occupied by either one or two traders. There are three male traders for every female trader and 89.4% of all stalls are occupied exclusively by one gender. The mean trips produced by a stall in a typical business day is 2.7 trips, with a variation from 0 to 10 trips. In the CBD, an average stall produces 4.4 trips while stalls in the periphery generated an average of 2.1 trips. Small stalls generate two trips, while medium (3 occupants) to large stalls generate twice as many trips. While stalls occupied exclusively by males have a mean of 3.0 trips, female-occupied stalls generate only 2.0 trips. On the other hand, stalls which have a personal means of transportation generate more trips than stalls where none existed. Even though the maximum number of a personal means of transpor- tation available to a stall was two, there was a sub- stantial difference between the number of trips pro- duced by stalls with the maximum number of vehicles and stalls where vehicles were unavailable. Finally, while provision goods stalls generate a mean of 3.3 trips, foodstuffs stalls generate about 2.1 trips, with intermediate results for other commodi- ties.

For policymaking purposes, there is empirical evi- dence to show that traders, together with consumers, contribute to off-peak trips which directly impact the urban transportation system. There is the need to evolve policies to minimize the frequency of trips by traders, especially by discouraging multiple tripmak- ing because it will contribute to a reduction in the amount of resources allocated to the upkeep of the urban transportation infrastructure.

The development of domestic water transporta- tion in the Philippines. Badon, Suzzette Brita. University of Hawaii, 1989. 259 pp. Chairman: Jo- seph R. Morgan.

Order Number DA9018958

This study analyzes the structure of maritime trans- port in the Philippines as it relates to the broad

Recent Doctoral Dissertations 117

framework of spatial hierarchical relations. A frame- work for analysis of development of transport sys- tems is provided, with special attention to the role of institutions in effecting changes and in transforming geographic space through technological innovations and implementation of policy directives.

The private sector traditionally offered a wide range of shipping services with minimum involve- ment by the government. Containerization, intro- duced in 1976 along major routes proved to be a success, and palletized roll-on/roll-off (RO-RO) ves- sels have gained acceptance on the shorter ferry routes. Although the static transport structure has remained basically the same, both qualitative and quantitative changes have taken place in both the nature and magnitude of flows.

There has been greater involvement by the gov- ernment over the past two decades, and the industry has become a public utility under Philippine legisla- tion. Overcapacity, poor safety records, and low ser- vice standards resulting from division of institutional responsibilities, were the major reasons for regula- tion. Institutional changes under the Martial Law regime allowed political favoritism and the imple- mentation of policy directives which contributed to the high costs of inter-island shipping and to high prices charged to users.

The regulated liner sector is dominated by three big shipping companies. Together with several oth- ers, these companies are organized into a shipping conference which functions as a cartel in all major and secondary routes. The operations of the cartel have been supported by the regulatory regime through policy directives, particularly those which limit competition and the perpetuation of the exceed- ingly high rigid tariff.

A developmental approach to urban transport planning. The Urban Transport Planning Pro- cess and its derivatives: An assessment of their contribution to transport planning for Third World cities. (Volumes I and I I ) . Dimitriou, Harry T. University College, Cardiff (Wales) (United Kingdom), 1989.465 pp.

Order Number BRDX92084

This thesis is in three parts. The first part provides an outline and critique of the Urban Transport Plan- ning (UTP) Process and its derivatives, tracing its evolution in the U.S. and its application to other industrialized nations. The critique of this methodol- ogy and set of techniques is based on an extensive literature review and interviews conducted by the au- thor with theorists and practicing professionals in the U.S., most of whom are at the forefront of the field or who have been pioneers of the approach.

The second part of the thesis concerns the tech- nology transfer of this same process to Third World contexts. The discussion draws from a review of lit- erature in the field and interviews conducted by the

author among those concerned with Third World ur- ban transport. This part of the thesis begins by out- lining the general features of Third World urban de- velopment as a basis upon which to assess the suitability of urban transport planning studies em- ploying the UTP process and its derivatives. Particu- lar attention is paid to the agents of technology transfer in this field, the role of technical assistance, and the role of consultants. The need to incorporate some consideration of settlement and transport hier- archies in the planning response to urban movement problems is also discussed. This provides one of the main planks of the proposed "developmental ap- proach" to Third World city transport planning which advocates the assessment of transport plans first, on the basis of their "developmental effective- ness" and second, in terms of systems "operations efficiency."

The third and final part of the thesis translates the theoretical framework and guidelines of the "de- velopmental approach" to urban transport planning into more specific terms. It does this by addressing the planning needs and characteristics of the Indone- sian urban transport sub-sector, making particular reference to the problems and needs of five Javanese cities. The approach arrived at as a result of this more detailed analysis is one which offers a system- atic collection, analysis and synthesis of data of value to urban transport planning in Indonesia. It incorporates a sketch-plan methodology intended to provide a robust and flexible low-cost approach for settlements with populations between 150,000 and 1,000,000.

Investigation of the effectiveness of selected in- tersection transportation system management techniques and traffic enforcement levels in a developing country: Jordan case study. AI-Ba- kri, Ala A A. Yousef. The University of Iowa, 1990. 375 pp. Supervisor: James W. Stoner.

Order Number DA9112390

This study evaluates the effectiveness of TSM im- provements in developing countries, with Jordan as a specific case study. A before and after analysis of seven selected intersections that have been changed from roundabouts to signalized intersections is per- formed using accident prediction models developed as part of this dissertation. A methodology for TSM and enforcement evaluation is achieved using gener- alized linear models; an evaluation of seat belt usage and enforcement policy is developed using time series analysis.

It is estimated that additional enforcement levels are associated with an approximate 20% reduction in accidents for one year and by 40 accidents a month for 10 years. It was found that intersections are safer than roundabouts, with the difference in safety de- pending on the speed limit of the approaching roads.

118 Recent Doctoral Dissertations

Generalized linear models were fitted to relate the number of accidents to geometric and flow variables. Other models that include both entering and ap- proaching accidents were fitted. For signalized inter- sections, the effect on the number of total accidents of increasing the flow depends on the speed limit of the approaching road.

The introduction of a seat belt law in Jordan re- sulted in a reduction of casualties by 1 unit during the transition period for seat belt usage, followed by a reduction of 3 units during the period of enforce- ment of seat belt usage on the highways and within city limits, and an increase of 77 units in the number of casualties during the period of enforcing seat belt usage only on highways. The overall effect of seat belt policies is to reduce the number of casualties by 2 units. Similar results are found using both injuries and fatalities.

The link between travel time reliability and the technology choice of the firm. Hansen, Alec Lars. Boston University, 1990. 171 pp. Major Pro- fessor: Michael Manovc.

Order Number DA9019695

This study examines the effect of commuting time variance on productivity. The benefits of urban transportation investments for commuters have been treated extensively, but the benefits to firms have received scant attention. Demonstrating that these investments can boost not only short-term consump- tion but also long-term growth would enable policy makers in developing countries to justify directing more resources to urban transport. Commuter be- havior is captured with a stochastic departure time model, using uniformly distributed travel times. Travel time data and institutional case study findings from Lahore, Pakistan are used to support the anal- ysis.

Teamwork is identified as the main factor respon- sible for productivity losses when the transport sys- tem is unreliable. The proposition that firms using teamwork-intensive technologies will set higher pen- alties for late arrival is made, but not tested empiri- cally. Where labor laws and other institutional fac- tors preclude high penalties, firms are forced either to absorb higher losses, or to adopt practices that reduce their vulnerability to unreliable travel times. Such practices include: (i) purchasing and operating a bus service for company employees; (ii) hiring spare or reserve workers; and (iii) switching to tech- nologies with lower teamwork intensity.

In industries where labor demand is elastic, and (ii) or (iii) is taking place, the model predicts that total employment will rise once public transport re- liability is improved, even though the number of re- serve workers falls. Thus, in countries undergoing industrialization, the greatest employment gains would be in competitive and export-oriented mar- kets. The model framework can be used to analyze

the applicability of fiextime policies to firms using teamwork-intensive technologies. It is also suggested that investments that reduce travel time variance, such as bus-only lanes, signal priority for buses, headway control measures, and improved traffic po- lice enforcement are more cost-effective than pre- viously thought, as compared with investments aimed at reducing average travel time, notably high- way construction.

The location of transport infrastructure and the policy-making process: Port terminals and modal networks for NSW export coal in the post 1970s. Everett, Sophia Apolonia Maria. Uni- versity of Wollongong (A ustralia), 1989.

This study examines the mechanism of policy- making as it relates to the provision and location of coal transport infrastructure in NSW. The study suggests that traditional geographic theories and pos- itivist decision-making models do not adequately ex- plain location decisions and that, intuitively at least, it is apparent that the principles of economic ration- ality are inappropriate explanatory mechanisms. Rather, it is argued that comprehensive analysis of infrastructure location and provision requires an in- vestigation into the policy-making process itself.

This thesis focuses, therefore, on the relationships between the policy-making process and the location of transport infrastructure. Its perspective is loca- t i o n a l - t h e pattern and structure of transport net- works for NSW export coal from the early 1970s; hut its analytical focus is the mechanism of transport policy-making and decisional analysis which reveal the fundamental nature of the policy p roces s - t he elements involved, the power linkages, the "play of power."

The study adopts a pluralistic perspective and ar- gues that while policy decisions are made by a rela- tively small number of decision-makers, the ultimate choice of action, in this instance infrastructure provi- sion and location and its eventual implementation, is the outcome of an intricate and complex "play of power." The thesis is structured around four detailed case studies, each of which exemplifies not only par- ticular aspects of the policy-making process but also the relationships between the process and the actual structure of the transport system.

Mode choice models and users' preferences to different submodes of road-based public trans- port. Dardak, Achmad Hermanto. University of New South Wales (Australia), 1990.

Presently, many cities of the developing world are tending to make small buses less important. This ap- pears to be in contrast with the present policy direc- tion in many cities of the developed world. This re- search attempts to address the above issue by

Recent Doctoral Dissertations

predicting users' preferences to different submodes of road-based public transport (stage bus, minibus, microbus) in a quantitative way.

The historical background of road-based public transport in many cities throughout the world is briefly reviewed. This is followed by a discussion of the current role of different submodes of road-based public transport. One of the individual mode choice frameworks is chosen and a computer program is developed which includes the estimation procedure and non-linear optimization to construct mode choice models to different submodes of road-based public transport in a case study area.

The case study area selected is a 10.5 kilometer main road corridor in Jakarta, where all submodes of road-based public transport are in direct competi- tion. Jakarta's 1985 Home Interview Survey and the Bus Counting Survey conducted by Pacific Consul- tants for Bina Marga, are used as the main data sources. These are supplemented by primary data collection: extensive surveys that include land use information in the corridor, travel times measured for each public transport submode and access time on foot and/or by becak, reasons for using particu- lar public transport submodes obtained by interview- ing passengers, and a frequency count of each sub- mode to established passengers' probable waiting times.

This thesis makes an important contribution to the survey, analysis, and modeling of commuter mode choice and users' preferences in those situa- tions where stage bus, minibus, and microbus are in direct competition. In general, a model with more explanatory variables shows better predictability. The elasticities were found to be higher than passen- gers' elasticities in other cities.

This research concludes with an account of the usefulness of structuring and modeling decisions to provide predictive and evaluative outputs that can be used by decision makers. The results show that microbuses are preferred as compared with stage buses. Microbuses are popular for, inter alia, shorter distances of less than 6 kilometers, females, higher income groups, and higher occupation status groups.

Populat ion mobility and the urbanisation of ru- ral communities: A case study of the Glens of Antrim. (Volumes I and II). McNaughton, Mary G. University of Ulster (Northern Ireland), 1986.494

PP. Order Number BRDX91811

This thesis examines certain geographical aspects of contemporary rural society-particularly the rela- tionship between rural communities and urban cen- ters. It does this through the analysis of different types of mobility patterns exhibited by one rural communi ty - the Glens of Antrim, an area of pri- marily dispersed settlement in north-east Ireland.

119

Most of the study is based on the results of a ques- tionnaire survey conducted in the Glens in 1980, sup- plemented by material from other sources, chiefly historical information from the census.

The types of mobility examined through informa- tion gathered from the questionnaire survey were res- idential mobility; journey-to-work patterns; con- sumer behavior; and patterns of social activity. Each of these types of movement was analyzed separately in relation to a number of individual or household factors, including location, demographic, and socio-economic characteristics. Other factors such as destination, distance traveled, and frequency of movement were also considered. For each aspect of mobility, the impact of the observed patterns on the study area was assessed.

A factor given particular attention was the effect of rising levels of personal mobility as represented by the increasing incidence of car ownership, and the implications of this for the accessibility of carless households. The interrelationships between the dif- ferent types of mobility were also discussed. Of spe- cial interest were the roles of households which had migrated into the area from towns and also those which had members working in urban areas.

It was found that whereas economic l i n k s - a s represented by shopping and commut ing-had a marked urban orientation, other forms of mobility showed a more rural-based pattern. In particular, migration reasons tended to be domestic (e.g. mar- riage) rather than economic, and it is suggested that commuter mobility has partially replaced residential mobility. Social activity patterns remained firmly rooted in the local area, in contrast to findings else- where. These are indications that, instead of acting solely to undermine rural communities, the economic links with the towns have enabled them to adapt to the changing circumstances of the late 20th century with their social structure basically intact.

A road network improvement system (RONIS) for low-volume roads in developing countries. Turay, Samuel Brima. University of Waterloo (Can- ada), 1990.

Funding for road surface improvements has not been able to keep pace with needs in most highway depart- ments. Consequently, it has become more and more necessary to develop more effective procedures for managing the road network, including the efficient programming of projects to make the best possible use of limited funds.

The development of models to aid investment de- cisions for the road sector in developing countries received impetus about two decades ago through work initiated by the World Bank Group. Today, such comprehensive models as the World Bank's Highway Design and Maintenance Standards Model (HDM-III) are available. What is needed, in addi- tion, are methods for taking over when the basic

120 Recent Doctoral Dissertations

investment decision has been made in order that spe- cific and optimal program and budgetary planning lists can then be produced on a short-term and de- tailed basis.

To detail improvement needs, to group them into viable projects, and to refine the program of works, the procedure requires performance prediction mod- els which suit the needs of growing data bases in these countries. A Markov-based modeling tech- nique is used for this purpose. To plan resources more effectively and to schedule projects at the net- work level, a near optimization heuristic technique involving marginal analysis is developed.

This thesis describes the basic components of such a procedure, and the development of some of the key technology required for the road sector in developing countries. By applying a rational approach, the problem can be greatly simplified to assist highway departments in their budgetary allocation decisions.

The procedure was then applied to an actual sam- ple network in Sierra Leone involving 80 sections totaling about 700 kilometers. Reasonable results were obtained. The scope of the procedure should be expanded to include more improvement alternative strategies and resource constraints because of their proven potential for increasing effectiveness in the decision-making process. This can help in making a convincing case to senior decision makers for in- creased funding allocations.

Transferability of mode choice models within Saudi Arabia. A1-Ahmadi, Hasan Musaed. Michi- gan State University, 1989.223 pp.

Order Number DA9028619

The main purpose of this research is to determine whether the cost of developing, calibrating, and test- ing intercity mode choice models for Saudi Arabia corridors can be reduced by transferring models across corridors. To accomplish this purpose, inter- city mode choice models were developed and cali- brated for two major corridors in Saudi Arabia: the Dhahran-Riyadh corridor and the Jeddah-Riyadh corridor. A gender model was developed using data from both corridors, and the accuracy of transfer- ring each specific model was compared with that of the general model.

Several approaches were used to test the transfer- ability of intercity mode choice models. The first approach was to determine if the calibrated model could be used "as is" to predict intercity mode choice in another corridor in Saudi Arabia. The second ap- proach was to determine the accuracy achieved by updating the coefficients and constants of the model using sample data from the corridor where the model was being transferred. In the third approach, it was assumed that the specification of the original model could be used with re-estimated parameters from the test corridor. Finally, a modified approach was used.

This modified approach consisted of two forms. One form of the modified approach was to use a separate scaling factor for each variable, while the other form used distance as the scaling factor.

The results of the attempt to transfer models be- tween corridors without modification was not en- couraging. However, the modified approach gave an acceptable goodness-of-fit. Furthermore, by using the Bayesian updating method, the goodness-of-fit measure improved in both corridors.

The conclusion reached in this study was that transferring models across corridors in Saudi Arabia is feasible, and the potential cost savings to the king- dom can be significant. It is recommended that addi- tional corridors be studied to verify the universal application of the transfer techniques.

Urban transportation in Brasflia: Effects of physical and socioeconomic urban planning and transportation policies. Amin, Mostafa Abdel-Meguid. University of California, Irvine, 1990.237 pp. Chair: James J. Flink.

Order Number DA9103376

The dissertation examines physical and socioeco- nomic urban planning and transportation policies in Brasilia. It also examines international movements of urban planning and automobile industry.

The dissertation states that the urban transporta- tion problems in Brasilia originated from the misun- derstanding of Brazil's socioeconomic reality while planning Brasilia and while establishing the automo- bile industry in the country. Brasilia was built fol- lowing the Modern Movement of urban planning that is based upon dynamism of population mobility through multiple modes of transportation. The auto- mobile has been the only means of transportation that fits the city. Rapid mass transit has been diffi- cult to implement because of the dispersal settle- ments of the city and the low population density in the corridors linking these settlements. The working class unexpectedly lives in the satellite cities and works in the Pilot Plan, the center of activity. The implementation of the automobile industry in Brazil failed to offer the automobile as a mode of transpor- tation to the working class; instead, this working class was left with the high fares and only alternative of public mass transportation, the bus system.

Urban transportation policies in Brasilia in at- tempts to solve these problems have not been effi- cient mainly because of: the lack of consideration of an economic base for the capital city besides federal employment which is concentrated in the Pilot Plan; the lack of community participation in decision mak- ing; the simultaneous planning in diverging direc- tions and lack of implementation; and the consider- ation of expensive rail system projects instead of improving the existing bus system.