Urban Planning
Abstract
Land-use and development density decisions have always been amongst the most controversial issues in urban planning. Various approaches have been proposed to deal with these decisions. However, these approaches have been mainly theoretical rather than practical. Transit Oriented Development (TOD) is ...
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Land-use and development density decisions have always been amongst the most controversial issues in urban planning. Various approaches have been proposed to deal with these decisions. However, these approaches have been mainly theoretical rather than practical. Transit Oriented Development (TOD) is amongst the most recent approaches to urban planning and, consequently, land-use and development density decision-making. TOD has been defined as “a compact, mixed-use, community, centered around a transit station that, by design, invites residents, workers and shoppers to drive their cars less and ride mass transit more.” This paper aims at proposing a mathematical model for land-use and development density decisions based on the principles of TOD. TOD is generally considered to have three dimensions: design, density and diversity. Design needs to be prepared according to specific conditions and circumstances of each particular station area. On the other hand, planning for development density and diversity needs to be developed from a holistic viewpoint, regarding different macro-scale objectives and constraints. In this paper, the problem of development density and diversity optimization based on the principles of TOD is modeled as a mathematical programming problem with multiple objectives. The first objective is to maximize development density in station areas, and the second objective is to minimize the difference between each station’s ratio of job-housing balance and its ideal value (ratio of employed people to the number of residential units) in each TOD area. Several constraints related to the objectives of Tehran master plan have also been incorporated into the model. The resultant nonlinear model was transformed into a Multiple Objective Linear Programming (MOLP) problem using simple mathematical transformations. Then, using AUGMented Epsilon CONstraint (AUGMECON) technique, it was transformed into a single objective Mixed Integer Linear Programming (MILP) problem. Finally, the model was applied to a real case study in the 12th District of Tehran metropolitan area and the results were thoroughly analyzed. Statistical analysis of the results shows that the elasticity of diversity to development density is -1.017. In other words, 1% improvement in diversity leads to a 1.017% decrease in the development density index. Optimal trade-off between these objectives depends on (1) their relative impact on car ownership ratio, vehicle-miles travelled and similar criteria, (2) particular micro-scale issues of each station area as well as the goals and strategies of the municipality for each station area. Previous studies show that land-use diversity has a higher impact on the aforementioned criteria than development density. However, these results depend highly on urban development, urban transportation patterns and the behaviour of citizens. Hence, proper decision-making needs a separate study on the aforementioned impacts on travel behaviour of the citizens in the context of Tehran. Furthermore, the Pareto solutions of the proposed model provide a set of alternative development policies and enable the policy-makers to select among them based on their specific conditions and limitations. The proposed model results can be applied to future urban development plans.
Urban Planning
Bahram Amin zadeh Gohar rizi; saeid tohidi rad; Roshanak Asadi
Volume 5, Issue 19 , August 2016, , Pages 15-26
Abstract
Land-use location planning is one of the most important urbanism issues with different scales. The choice of location planning method is determined by the kind of problem and the importance of the supposed Land-use to be location planned. For example, to choose a location from some limited options, the ...
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Land-use location planning is one of the most important urbanism issues with different scales. The choice of location planning method is determined by the kind of problem and the importance of the supposed Land-use to be location planned. For example, to choose a location from some limited options, the multi-attribute decision making methods should be used; but when there is no initial option for location planning, the multi-objective decision making method should be used. Nowadays, the use of computational techniques for location planning is inevitable. The reason is that a manager's decisions in this field are influenced by various qualitative and quantitative factors, generally in conflict with each other, so that optimization of a factor may lead to the destruction of other factors. Thus, to prevent errors in decision-making, multi-objective decision-making techniques have been considered and used in recent years. There are different methods for solving multi-objective decision making problems which are categorized into two general groups: decomposition methods and direct methods. In the decomposition methods, first, the multi-objective optimization problem turns into a single-objective problem and then the problem is solved. However, in multi-objective optimization methods, the problem is solved in a multi-objective manner. Decomposition methods comprise of the 4 techniques of Weighted sum, Goal programming, Goal Attainment and -Constraint. Each of the 4 techniques tries to simplify the problem and solve it with specific measures. To turn a multi-objective problem into a single-objective one, these methods are forced to lose some of the space decision information. To solve this issue, the problem should be solved several times, which is very time-consuming. Furthermore, each time the problem is solved with these methods, a different answer is obtained. However, direct methods are not faced with this problem and are much faster and more accurate. The purpose of this study is to introduce an efficient technique of direct methods to solve all the multi-objective location planning problems and resolve classic and decomposition methods issues. Therefore, an airport location planning problem for the one of the major cities, based on Non-dominated Sorting Genetic algorithm (NSGA-II) was considered as a case study. Based on indicators such as easy access, noise pollution reduction, visibility, and access to infrastructure, the problem was modeled as a mathematical programming problem with 6 objective functions such as the minimum distance from main roads and highways, maximum distance from industrial factories, minimum distance from power transmission lines, maximum distance from the city and traditional gardens, minimum distance from the main gas transportation pipeline, the maximum distance from residential areas around the city and a certain number of required conditions. Finally, amongst the 200 final solutions of the proposed algorithm, including different front solutions, a solution with 4 points was chosen as the optimum location for the construction of the airport. Because of greater speed and accuracy, as well as providing a decision support system, the Non-dominated Sorting Genetic algorithm (NSGA-II) which is a direct multi-objective location planning problem solving method, can be considered as an appropriate alternative to the Decomposition and other traditional multi-objective location planning methods.
