A space syntax based model in evacuation of hospitals

Abstract

The concept of architectural design comprises problems such as perception and security especially in buildings having complicated circulation systems. In complex buildings many functions take place at the same time and within different behaviour modes. Besides their functional complexity, the designs of these buildings present perceivably complicated spatial appearances.Either linear or circular in architectural geometry, the shape of the building, affects the legibility of the spaces. In design process complicated buildings turn into some spatial plots with unclear circulation systems where entrances and exits have no significance in memory. As an example of a complex building, hospitals reflect similar circulation system problems. Considering the different characteristics of the patients, the hospital emergency evacuation systems present questions to the design process. The legibility of the building and the means of way finding are important aspects of evacuation. The parameters affecting the legibility of hospitals may be considered as the geometric shape of the corridors, the ergonomics of the spaces as well as the characteristics of occupants. These parameters are considered as passive prevention factors against any event or disaster. This research eliminates the active prevention factors of emergency safety system. The evacuation of hospitals can be discussed within the context of architectural legibility. Architectural theory mainly focuses on this issue especially in scope of perceptive and cognitive studies. The architectural path analysis in way finding, “node theory” and “graph theory”, are considered as an extent of circuit theories. The evacuation of buildings can be argued with occupants’ movements. The occupants’ flow on circulation systems, confrontations with others in emergency cases, occupant’s competence such as speed and even their postures can shape the nature of occupant traffic in buildings. The theoretical framework depends on an intersection area of various disciplines such as crowding of occupants in fluid-flow model in traffic engineering, competence of occupants in crowd behaviour model in psychology and real integration, visibility area - isovist values of Space Syntax model. The integrated model of egress proposes six factors based on various models; the crowding in the space, the competence of the occupants,the spaciousness factor of the space,the integration value of the space,the visibility area of the occupants and the distance between the egress point and the space. This research deals with one of the wings of the plastic surgery department located at the fifth floor of the General Surgery Building of Istanbul University, Istanbul Medicine Faculty as the case study; examines the exemplary emergency hospital evacuation systems and presents a model related to the spatial, ergonomic and perceptive parameters. The plan layout of the selected wing is subjected to five analyses. The real integration values of the selected wing are obtained through s-partition analysis of Spatialist. The values obtained from the s-partition analysis presents 56 visual space cells enabling a virtual base for the determinations, as well as the isovist areas. The cells located on the circulation routes are more integrated compared to the cells located on rooms. Certain central spaces in the system, used mainly by the staff, have the highest mean depth values of the whole plan indicating a level of emergency vulnerability. The isovist area analysis points out that the visibility area of the cells located on the corners of the circulation routes have the highest values indicating a wider angle of way finding thus, a lower level of emergency vulnerability. The queuing crowd data indicates that especially spaces including more people such as the wards for patients are more vulnerable compared to professors’ offices. Distance parameter presents that farther the space cell is located from the egress point, the more vulnerable the cell gets. Spaciousness factor analysis indicate that as the l/w ratio gets lesser than 1, the value of emergency vulnerability tends to decrease. The correlations of parameters with the total VEV emphasize that the vulnerability of a building in emergency cases, is directly related with the syntactic value of real integration and the dimensional value of distance between the starting cell and the egress point. It is exposed that, although the distance from the starting point to egress point may quite be within the limits of existing standards and codes, the results may not be sufficient enough to avoid vulnerability. However, in this research, the model emphasizes that human factor, geometrical structure and the Space Syntax inputs are especially effective for the evaluation of evacuation vulnerability.

Özet

Özellikle karmaşık dolaşım sistemleri olan binalarda algılama ve güvenlik problemleri mimari tasarım kavramını etkiler. Bu durumun oluşmasındaki ana nedenlerden biri, bu tür karmaşık binalarda birçok işlevin, farklı davranış kalıplarıyla bir arada yer alıyor olmasıdır. İşlevsel karmaşıklığın yanı sıra, bu tür binaların tasarımında mekânlar da algısal olarak karışık görüntüler sergileyebilir. Karmaşık binalar, tasarım sürecinde, belirsiz dolaşım sistemleri ve zihinde yer etmeyen giriş çıkışları olan mekânsal kurgulara dönüşebilir. Karmaşık binalara örnek olarak, hastaneler de benzer dolaşım sistemi problemlerine sahiptirler. Hastaneler birçok işlevden oluşur ve kullanıcılarının değişken becerilerine bağlı olarak gelişir. Diğer yandan, hastane acil kaçış sistemleri, hastaların farklı özelliklerine bağlı olarak tasarım sürecine önemli sorunlar getirir. Bu tür karışık binaların tahliyesinde, binanın okunulabilirliği ve yön bulma becerisi önemli etkenlerdendir. Hastanelerin okunulabilirliğine etki eden değişkenler arasında koridorların geometrik şekli, kullanıcıların özellikleri ve mekânların ergonomisi bulunmaktadır. Bu araştırmada, acil durum güvenlik sistemleri içinde yer alan aktif önlem etkenleri göz ardı edilerek, hastanelerin tahliye sistemlerindeki pasif önlem etkenleri ele alınmıştır. Çalışmada yer alan bütünleşmiş acil çıkış modelinde, mekândaki kalabalıklık, kullanıcıların becerisi, mekânın ferahlık değeri, mekânın bütünleşiklik değeri, kullanıcıların görüş açısı, mekân ve çıkış noktası arasındaki uzaklık gibi altı değişken ortaya konmaktadır. Çalışma, İstanbul Üniversitesi, İstanbul TıpFakültesi, Genel Cerrahi Binasını araştıma konusu olarak ele almakta, hastaneler için örnek olabilecek bir acil kaçış sistemini incelemekte ve mekânsal, ergonomik ve algısal parametrelere dayanan bir modeli ortaya koymaktadır. Araştırmada önerilen model, insan faktörü, geometrik yapı ve mekânsal dizim girdilerinin, acil durumlardaki etkilenebilirliğin (vulnerability) değerlendirilmesinde özellikle etkili olduğunu vurgulamaktadır.