Urban growth

Like other developing countries, Iranian cities are growing and expanding physically at a high speed. For about five decades, the only policy of the urban development plans in the field of urban growth management has been definition of the Urban Growth Boundary (U.G.B.) which is still used without any major modifications. Despite the slight evidences indicating the ineffectiveness of the current policy, there has not been any assured and agreed alternative yet. Today, the waves of new urbanism and other modern paradigms have urged temptations of making fundamental changes in the definition of urban growth boundary. Through an analytic framework, this research investigates the effectiveness of some of the most basic carriers of urban growth in 11 sample cities (each of them introducing one type of Iranian cities). The results of this analysis will illustrate a new vision- a native one - for alternative policies of urban growth management in Iranian cities.

Bangladesh is still a low urbanized country although it experienced a rising trend in the level of urbanization throughout the twentieth century and had a remarkably high urban growth immediately after its independence in 1971. The country recorded the highest ever annual average growth rate (9.04) and percentage of interval variation (137.57%) in an urban population in 1974; thereafter, growth rates of these two parameters went on falling and reached 5.19 and 65.89% respectively in 1991. As a result, urbanization during the tail end of the twentieth century increased but at a decreasing rate leading to an unsustainable urban growth trend. This study, however, exامینes the factors that contributed to urbanizing Bangladesh during the unsustainable growth period particularly in the last decades of the twentieth century. To this end, a multivariate regression model is developed and analyzed using the ordinary least square method involving stepwise-regression procedure. Primarily ten potential factors are taken into consideration and seven of them emerged as significant in explaining the process of urbanization in Bangladesh. Of these seven factors, the level of industrialization appears as the most influential factor with a coefficient of 1.34, which is followed by the share of urban area, initial level of urbanization and migration with coefficients of 1.13, 0.86 and 0.49 respectively; while the econometric model came up with an adjusted R2 of 0.95 and the Durbin-Watson Statistic of 1.98. Results of this study provide with better understanding towards guiding the urbanization process, particularly in the developing countries.

During a very long period of time, civil engineers have been the only ones to be designated as the experts for underground space, while the planners and architects were the ones of the development at the surface. Cities worldwide tend to overlook an invaluable asset that lies beneath their surfaces. Most cities and urban regions are unaware of the benefits underground space use has to offer, both for climate inflicted and spatial constraints: In many cities, infrastructure development is being outpaced by population Growth. Climate change effects are requiring radical new approaches in terms of coping with for example excessive rainfall. The available space at the surface is rapidly being used up and the biggest danger is that built-up spaces are taking over the public green spaces of cities thereby threatening livability and quality of life. Urban underground space forms a societal asset, which is often unappreciated and underestimated in terms of the role it can play within dynamic city environments and associated challenges. The world-wide trend of increased urbanization creates problems for expanding and newly-developing cities alike. Population increase leads to an increased demand for reliable infrastructure, nowadays combined with a need for increased energy efficiency and a higher environmental awareness of the public. The use of underground space can help cities meet these increased demands while remaining compact, or find the space needed to include new functions in an existing city landscape. Use of Urban Underground Space (UUS) has been growing significantly in the world’s biggest and wealthiest cities. UUS has been long acknowledged to be important to the urban development agenda: sustainability, resilience, livability, and creating a better urban environment in particular.

Today each city due to natural limitations, facilities and planning policies has different growth pattern which according to its spread, has different consequences and results. Although there is a wide range of urban growth patterns, but the important thing is not diversity and number of models but is the absence of rules and methods of transition from one to another pattern (form). So this article review and analysis ways which we can achieve this transition in the pattern of urban growth. Evidence shows that in order to transition from the pattern of automobile-dependent city (modern) to post-industrial and post-modern models, there are different approaches, including urban containment, urban consolidation policies, new urbanism, smart growth, emphasis on infill development and transit-oriented development and it is considered that the most important thing in all of them, is the relationship between land use and urban transport. In fact, the key of many compact city debates is transit-based transportation systems and urban mixed landuse that reduces use of machine and limits travel time for commuters. Also transition has multi-level perspective: first are niches (technological innovation in transport and landuse, second are regimes (regulation and governance that provides appropriate frameworks, guidelines and rules for transition) and finally are landscapes (the broader conditions, environment and pressures for transition).