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This study arose from an idea that air pollutants and greenhouse gases from vehicles could be reduced by changes in urban form. Analyzing the results of related prior investigations showed that the researchers mainly argued that adjustment of typical urban form characteristics (e.g., degree of population density or sprawl) can reduce the amount of vehicle emissions. The policies considering typical urban form change cannot be easily realized, however, because changing population density and stopping urban sprawl are both very difficult and require a long time. In view of that limitation, this study tried to uncover more effective urban form factors to reduce vehicle emissions within the mid- or short-term. This research also attempted to examine vehicle emission reduction by changing both absolute and relative locations of urban functions (i.e. population, employment, and commercial facilities). To observe the relationship, some spatial-related variables from the location of urban functions are developed.To determine the relative location among urban functions, certain measurements are built. Based on the location concepts, key variables are constructed. Average daily vehicle miles traveled (ADVMT) is estimated to measure the amount of vehicle emissions, and then statistically tested its relationship with eight urban form factors. Based on the analysis results, when we have urban areas with similar population densities, an area with clustered populations and closely concentrated clusters produces fewer ADVMT and emissions. In addition, a short average distance between residences and the commercial areas they use frequently generates fewer emissions, too. The results also show that high population density, employment centrality, and longer commuting time also reduce vehicle emissions.This study additionally simulates the change in vehicle emissions based on residential development scenarios. The results show that residential development in suburbs considerably increases both VMT and vehicle emissions, compared with development in a downtown area.Based on the estimated VMT and quantity of vehicle emissions in the urban areas, there are definite differences according to the conditions of urban form factors. In addition, according to the simulations, considerable benefits exist with decreasing the quantity and costs of vehicle emissions through the changes of urban form factors.This study verifies the relationship between VMT, the quantity of vehicle emissions and urban form factors with a distinctive approach that also includes conventional factors. This study emphasizes the importance of the distribution of populations and other urban functions. |
