Transportation and the location of interactive activities.

摘要

Location problems consider the trade-off between the benefits for activities to occupy land and its associated site characteristics and costs for activities to interact with other activities over the space. In this research, we assume site characteristics of all land are the same everywhere in a city, and the interaction between activities over the space is facilitated by transportation. The goal is to find the optimal and equilibrium density of households and locations of interactive activities.; The optimal location of activities was found to be a median location. If we assume trips to/from a facility in each direction exert on that facility a force proportional to the trip frequency to extract it toward that direction, the median location of the facility is the location where the extraction forces toward all directions reach an equilibrium. This finding extended Weber's theory from the location of one plant to the location of many interactive activities.; The optimal density of households at each location in a city is a negative exponential function of a household's travel cost. This finding establishes a direct relationship between transportation cost and household density, extending the monocentric urban economics model to a polycentric model.; The comparison between optimal and equilibrium locations suggested that the equilibrium location of activities is usually not the optimal location. However, if discriminatory locational rents can be charged, equilibrium location will also be an optimal location. The information needed to construct the structure of the discriminatory rent is inter-activity transportation cost. This finding supports the current practice of charging developers traffic impact fees according to excess traffic they generate.; Based on findings on location and density, a general location model with endogenous inter-activity trips and endogenous number of facilities was developed and algorithms were designed to solve it. In addition, a city with two transportation modes was analyzed. Further, implications to current policy issues were briefly discussed.