Study On Urban Form And Travel Demand Based On Self-organization And Multi-agent System

China is in the stage of rapid development of urbanization, of which the scale isenormous. Megalopolises are constantly emerging. Traffic, energy consumption andenvironmental problems become increasingly serious, which bring down the efficiencyand livability of cities. Most of urban problems, especially traffic problems, are relatedto irrational land-use form. Urban development and the relation between land-use andtravel demand have been the hot spot of academic attention.Self-organization is one of the main forces that affect the city evolution and shapethe urban form. To guide the city to a benign development, it is necessary to understandand grasp the law of self-organization evolution of city. The thesis reviews theself-organization and hetero-organization in the history of city development andelucidates the significance of studying self-organization. An urban spatial formevolution model base on new economic geography and urban system dynamics is built.In this model the city contains consumer service industry and producer service industry.The residents, being consumers and labors at the same time, have a preference forvariety in consumer goods and choose their residence and workplace on the principle ofutility maximization. Commuting cost is introduced and house-job separation isconsidered. Through simulations of cities of various forms, in which differenttransportation cost parameters, including transportation cost of consumer goods andintermediate goods and commuting cost, are adopted, the paper studies the evolution ofindustry and population distribution of several typical urban forms underself-organization condition and exhibits the influence of transportation cost and locationcharacter on urban industry and population distribution. The results demonstrate thepossibilities of mono-centric and multi-centric pattern of the two industries during theevolution. City has the nature of aggregation. Depending simply on self-organization ofmarket, it is hard to form a multi-centric pattern.The thesis then focuses on the travel demand of city of a specific form. Firstly, thestrength and weakness of mono-and multi-centric city are discussed and the concept ofunit city is introduced. A bottom-up micro-simulation model based on multi-agentsystem is developed, applying the achievements of bid-rent theory, economic geography and transportation planning theory and considering the influence of family structure andthree kinds of trip–commuting, consuming and business trip. The differences of trafficefficiency and carbon emission between unit city and mono-centric city are investigatedquantitatively. The results indicate that for cities over a certain size, unit city performsbetter in travel demand reduction, energy saving and emission reduction. A unit cityplanned rationally can reduce over40%long-distance trips and about25%trafficemissions.Based on the advantages of unit city, the thesis elucidates the details of planningidea and design principles of unit city. A conceptual planning and design for a virtualurban unit is conducted, including the basic form and travel demand, city structure, cityunit, unit group and transportation planning, which present a preliminary framework ofunit city planning.