Akira Ohgai

Cellular automata modeling of fire spread in built-up areas- : A tool to aid community-based planning for disaster mitigation

Abstract Japan has many built-up areas with a high proportion of old wooden structures. These areas will be badly damaged by collapsed buildings and the spread of fire in the event of a seismic disaster. The government is therefore focusing on the improvement of these areas. For the promotion of such improvement, there is a need to build consensus for disaster prevention countermeasures through community-based planning by both the residents concerned and the administration. In the present study, we developed a model as a planning support tool that can visually simulate the spread of fire. This model incorporates firefighting activities and can realistically show the detailed fire spreading process that traditional models cannot represent in built-up areas, using cellular automata. The model was applied to a historical built-up area in Japan. Based on the simulation results obtained by application of the model and the actual fire records of Japanese built-up areas, the calibration and reproducibility of the model were examined and reviewed. From the outcome of this process, we are confident that the use of simulation results is of value when examining the effects of improvements in the local environment during the collaborative planning process.

Multi-objective location modeling of urban parks and open spaces: Continuous optimization

Abstract In this paper, we present a multi-objective model with a promising application for facility location planning. The genetic algorithm (GA)-based multi-objective optimization model (GAMOOM) developed here is applied to the particular problem of obtaining optimum locations for urban parks and open spaces (POSs) by considering four incommensurable objectives: the provision of POSs near (1) densely populated areas, (2) areas with polluted air, (3) noisy areas, and (4) areas without POSs. The model is executed using real datasets collected from the city of Dhaka (as a case study). To assess the impact of each objective, computational results obtained from each objective function were compared. The second objective (air pollution) has been shown to have a significant impact on locating POSs compared to that of the other objectives. The results obtained using a composite objective function (by combining all objective functions) indicate that the model can successfully provide optimum locations for new POSs. This study also clearly demonstrates the importance of using a dynamic weighting scheme to convert all objective functions into a composite one. The model developed here has been found to incorporate an operator to successfully generate non-dominated Pareto optimal solutions and a Pareto front. The alternative solutions obtained here act as a candidate pool from which decision makers may choose the best solution according to their preferences or determinant criteria. The outcome of this multi-objective GAMOOM model consequently does have implications for how POSs should be designed and managed by planning authorities in order to maintain not only a sustainable environment, but also a better quality of life in the city.

Commercial facility location model using multiple regression analysis

This paper describes a simulation model for estimating radical changes in the location of retail facilities that is applied to the Fukuoka metropolitan area of Japan. The model has three important characteristics. First, it clears the retail employment by applying multiple regression analysis and a modified Huff model incorporating distance and population. Secondly, it allocates retail employment for two types of retail stores: convenience-goods stores and shopping-goods stores. Thirdly, it computes commercial floor area for each retail type.

Cellular Automata Modeling For Fire Spreading As a Tool to Aid Community-Based Planning for Disaster Mitigation

As a tool to support collaboration in community-based planning for disaster mitigation in Japanese old wooden built-up areas, we attempt to develop a fire spreading simulation model incorporated a fire fighting activity using Cellular Automata (CA). The proposed model can deal with the process of fire spreading in a building that traditional models can not represent. Whether or not fire can spread is based on a stochastic calculation process to reproduce uncertain fire spreading. The errors caused by the stochastic factor are analyzed by carrying out simulation two or more times under the same condition. Moreover, the reproductivity of the model is examined by comparing simulation results with actual fire records.

Modeling Land Conversion in the Colombo Metropolitan Area Using Cellular Automata

Abstract This paper proposes a Cellular Automata (CA) model to evaluate the urbanization patterns arising from the regulation of urban growth on paddy lands in the Colombo Metropolitan Region (CMR). Most of the historic map data available for the CMR before 1990 are temporally sporadic and spatially incomplete. As an alternative to maps, classified remote sensing data are used to analyze the urbanization process. Logistic regression is applied to derive factors of urbanization and the various relationships among them. The relation between ′urban′ and ′non–urban′ serves as an explanatory variable. The factors explaining that relationship are calculated by exploratory logistic regression analyses. The probability calculated from the statistical model is used for CA transition with a random number. Several growth patterns are simulated based on a range of transition thresholds to test the CA model. Status quo growth and several growth control scenarios are simulated for the period from 1987 to 2002 based on an optimum threshold. The simulation result of the status quo growth is evaluated with several evaluation methods. The level of agreement between the estimated result from the status quo model and the actual data is 62%, while the multi–scale goodness–of–fit method produces highly accurate values for the given range of resolutions.

A workshop support tool combining disaster-mitigation performance evaluation and virtual reality for the improvement of densely built-up areas

This study focuses on the difficult issue of building consensus among local residents participating in improvement planning for densely built-up areas with vulnerability to earthquake disasters. As an initial step towards the formulation of a method for building consensus in the participatory planning process, we attempt to clarify the issues involved based on a literature survey and interviews with professionals in the field; then, we examine the main factors affecting consensus building in improvement planning. The results reveal that the lack of performance evaluation of the draft plans for disaster mitigation during workshops as well as an inability to clearly share in visual form images of the prospective townscape after implementation of the plans, are among the main factors negatively affecting consensus planning. From this investigation, the study experimentally develops a tool to meet these challenges by enabling a quantitative evaluation of disaster-mitigation performance; at the same time, this tool can be used to show a virtual 3D image of the future townscape based on the draft plans examined during the workshops.

Estimating the Changing Distributions of Population and Employees by Cellular Automata

This paper aims to develop an operational cellular automata model to simulate the changing distributions of population and employees in a local city of Japan. The model is composed of two parts of process of these changes. In order to provide a realistic simulation of the distributions, we introduce a critical parameter representing the relation of zoning system in Japan and urban activity. The reproductivity of the model is examined by illustrating simulation results.

An attempt to implement tools to support examination of community-based activities for disaster mitigation: A case study in Toyokawa city, Japan

Japan is a country with a high risk for earthquake disasters. The measures used to promote structures’ seismic safety, such as reconstruction, widening narrow roads, and the response capacities to deal with huge earthquakes are important. Techniques to support the examination of countermeasures to huge earthquakes are required. To improve this capability, the authors developed tools to: (1) evaluate fire-spread risk, (2) evaluate the difficulty of emergency response and evacuation, and (3) evaluate capacities of neighborhood communities for disaster mitigation. The usefulness of the tools was clarified by the demonstration experiments of previous studies. The next step was implementation of the tools in community-based activities for disaster mitigation. This study aimed to clarify the usability and problems of implementing the tools in community-based activities. The tools were used at several workshops in actual community-based activities for disaster mitigation for one year. After the last workshop, interviews and a questionnaire were conducted on municipal staff and consultant staff. The results found that the tools visually showed the fire-spread risk, the difficulty of evacuation under current conditions and after improvements, and the effects of each disaster mitigation activity. The users could easily explore the draft plans to promote seismic safety of urban structures and response capabilities. The tools were positively incorporated into some community-based activities for disaster mitigation. Thus, the tools have the possibility of successful use at continuing community-based activities and the possibility of implementing the tools will be promoted.Japan is a country with a high risk for earthquake disasters. The measures used to promote structures’ seismic safety, such as reconstruction, widening narrow roads, and the response capacities to deal with huge earthquakes are important. Techniques to support the examination of countermeasures to huge earthquakes are required. To improve this capability, the authors developed tools to: (1) evaluate fire-spread risk, (2) evaluate the difficulty of emergency response and evacuation, and (3) evaluate capacities of neighborhood communities for disaster mitigation. The usefulness of the tools was clarified by the demonstration experiments of previous studies. The next step was implementation of the tools in community-based activities for disaster mitigation. This study aimed to clarify the usability and problems of implementing the tools in community-based activities. The tools were used at several workshops in actual community-based activities for disaster mitigation for one year. After the last workshop, in...

Application of Advanced Hybrid Genetic Algorithms for Optimal Locations of High School

In this study, an advanced hybrid genetic algorithms is formulated and applied to the optimal location of high schools in a rural area of Bangladesh. The advanced hybrid algorithms consist of genetic algorithm and alternating location allocation algorithm. The model is applied to Nakhla Upazila (a sub-district area) of Bangladesh as a case study. First, the genetic algorithm is used to generate optimum locations of high schools and then coded with the traditional alternating location allocation heuristic thus avoiding very long computation time. Obtained simulation results indicate that existing high schools are not well distributed and they are far from residential areas. The developed hybrid algorithm based model successfully shows the best locations of high schools in the Nakhla Upazilla minimizing the total amount of travel distance from the different zones of Nakhla Upazila to the school sites and thus provide a safe travel for children. The results have an implication for a good urban planning in context of placing schools optimally within walking distance of a neighborhood The model thus developed can be applied by planners as a useful tool for any location analysis.

Greenery-Based Model of Green Urbanism for Developing a Sustainable Healthy Livable City - Dhaka City's Perspective

In this paper, a model of green urbanism (GU) incorporating the concept of planting of trees and greeneries has been proposed. The GU model mainly attempts to address challenges encountered by dynamically changing cities around the globe due to the reduced number of urban greeneries transforming into built-up areas. A framework has been designed to develop a greenery-based conceptual model (GBCM) towards attaining sustainable healthy livable (SHL) environment. The model is discussed in terms of greenery-based urban strategies and methodologies to deal with the social and economic contexts particularly in Dhaka city. In this context, we first revisit the present state-of-the-art of greeneries in Dhaka, then examine whether Dhaka a SHL-city and finally, an attempt has been taken to revive GU in Dhaka to bring a sustainable healthy environment. The model has reconfirmed that greeneries are the roots of adopting green urbanism which could bring a number of fundamental environmental benefits including reduction in energy use, pollution, waste generation, emission of greenhouse gas, impacts on climate and occurrence of natural disasters etc. The model thus developed has an implication on how city planners can adapt a priori approach to ensure sustainable health of populations combating unprecedented social, economic and environmental challenges that make cities unsustainable, unhealthy, and unlivable (3U-cities) due to insufficient greeneries.