Developing an Urban Design Support System with GIS

Toward Solving Urban Planning Problems in Alexandria, Egypt

By Dr. Osama M. Abdel-Rahman, Assistant Professor, University of Alexandria

The urban center of Alexandria, Egypt—comprising Mohammad Ali Place, Orabi Place, and a large part of the urban fabric surrounding both—is generally overcrowded and contains a heterogeneous mixture of uses including residential, commercial, and administrative activities. Many parts of the area are home to high-density apartment buildings, shops, and offices. In poorer quarters, small industries and workshops are found alongside a number of sites of archaeological importance.

The area is of historical, architectural, and aesthetic significance to the history of the City. However, this area is also under continuous threat by the problems that accompany any redevelopment process, and which could severely damage its architectural and historical character. Therefore, there is a need to facilitate an in-depth yet dynamic analysis of the existing urban fabric. Such a system of analysis is the urban design support system (UDSS), a relatively new concept originating from the merging of GIS, CAD, and desktop multimedia data to constitute a good framework for exploratory visualization in urban design.

To introduce third-year students in the Department of Architecture at the University of Alexandria to a realistic application of GIS in urban planning, a project was designed to teach UDSS concepts. In addition, professional urban designers were invited to explore the potential of adopting such an approach, which would place more emphasis on the visual and functional attributes of the urban environment. In particular, the outcome of this project would introduce UDSS to Alexandria Comprehensive Master Plan (ACMP) authorities as an aid to support the application of conservation policies and development control within the City center.

The basic idea is that a piece of information about the way in which an urban space may look before or after development can be available at a click of the mouse. This information can be updated and modified quickly over time. These changes may take the form of a new photograph of an area after development or 3D computer images of the same area before and after development. Moreover, video clips can be hot linked to a specific pedestrian path.

In addition to this visual database, urban information can be added to include data concerning each individual building such as use, height, condition, area, or ownership. This may extend the platform of information available to the urban designer or any other interested parties.

Professor Mohammad Abdel-Aal, senior professor at the department and former Dean of the Faculty of Architecture of Beirut Arab University, says, "This project is promising and would be useful in several aspects concerning solving urban planning problems such as the growth conflict between the old and new urban fabrics in the area, the unplanned congestion in terms of vehicular and pedestrian movements in the City center, and the identification, conservation, and consolidation of key and historic buildings in the area."

Objectives

For the purpose of this research project, ArcView GIS is used as the basis of the UDSS. ArcView GIS provides a wealthy set of map visualization and analysis tools as well as map creation and drawing functions. It can also handle aerial photography, spreadsheet tables, and charts. This GIS runs on PCs within a Windows 95 environment in combination with AutoCAD 13.

The main objective of the project is not to establish a complete urban database of the area, but rather to give an example of a way in which this database may be constructed using the available tools. For the purposes of the course, the focus is on the method, techniques, and promises that UDSS would contribute to the field of urban design. The collection of data and creation of an urban database will come at a later stage.

The goals of the UDSS are threefold. First, the ability to visualize existing urban fabric and new design ideas within the context of this fabric is a vital element in urban design. The approach adopted here is to utilize a tool within ArcView GIS to visualize 3D models and photographs, which take place outside ArcView GIS.

Second, morphological analysis is an important aspect in urban and architectural design. Morphological analysis is based on three principles of form, scale, and time. Form can be defined by three physical elements: buildings and their related open spaces, land parcels, and streets. Scale is generally considered at four levels, ranging from individual buildings, building blocks, the city, and up to the regional level. The urban form can be understood historically since its elements undergo continuous transformation and replacement over time.

Third, there are important elements in the urban environment that constitute key features of the mental map of its inhabitants. These features are called landmarks, which may be key buildings of historical or architectural significance or both. Taking these key elements into consideration is of great importance to urban design.

Application

The field survey of the area was based on the hypothesis that urban spaces morphologically consist of streets and squares. Having identified specific urban spaces, a photographic survey was carried out in the field. The photographs consisted of 34 shots covering the 17 streets and squares. Two shots were allocated to each space, one at each end of it. The points of photography were annotated on a recent survey map of the area on the spot.

Having done that, the survey map was scanned and transferred to ArcView GIS. Within the project's view, several layers were created representing important "themes" such as the ground, the sea, the buildings, and the roads. The streets covered by the field survey were then highlighted and annotated. The points of photography were then drawn using the drawing tools of ArcView GIS and hot linked to the photographs, which were scanned individually and saved in a separate file on the hard disk of a portable computer.

A new theme containing the points of photography was created. The table of attributes of this theme was then provided with basic data about each shot. This included the serial number of the shot, the date it was taken, the name of the urban space it covers (be it a square or a street), the location of the shot, the direction to which the view is pointed, and image path information.

In addition to the photographic survey, the map of the area could also be hot linked to 3D images of a computer model to give an aerial view of the area from different viewing angles. However, further research should be developed to take this approach further to cover other urban planning information such as cadastral data and relevant building codes.

Professor Samir Hosni, head of the Department of Architecture, University of Alexandria, has suggested, "This work should be expanded further to collect and integrate information (both textual and photographic) into the project to cover all the architectural, archaeological, and historical features of the whole City. The project could then be presented to the governorate authorities of Alexandria to become a part of the City site on the Web to promote international tourism."

For more information, contact Dr. Osama M.A. Rahman, Department of Architecture, Faculty of Engineering, University of Alexandria, Alexandria, Egypt (e-mail: OsamaRahman@Altavista.com).

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