Safe City

Safe City

Assessment of Urban Green Space Arrangements to Reduce Explosion Impacts on Buildings

Document Type : Original Article

Authors
Ali Bitarafan 1
Seyed Bagher Hossieni 2
Gholam Reza Jalali 3
Seyed Abbas Yazdanfar 2
Saeed Norouzian 4
1 M.Sc. in Housing Architecture, Iran University of Science and Technology, Tehran, Iran
2 Associate Professor, Faculty of Architecture and Urban Planning, Iran University of Science and Technology, Tehran, Iran
3 Assistant Professor, National Defense University, Tehran, Iran
4 Assistant Professor, Faculty of Architecture and Urban Planning, Shahid Beheshti University, Tehran, Iran
10.22034/ispdrc.2022.254405
Abstract
Extended Abstract
Introduction
 Urban security and the reduction of vulnerability of critical infrastructures against man-made threats—particularly accidental or deliberate explosions—have gained increasing importance in recent decades. With rapid urbanization and the growing density of populations in metropolitan areas, urban design and planning with a passive defense approach has become an essential priority in the fields of architecture and urban management. Within this context, urban green spaces represent a vital layer of the city fabric with a dual role: on the one hand, they provide environmental and social benefits such as air purification, noise reduction, landscape enhancement, psychological well-being, and microclimatic regulation; on the other hand, they can act as natural shields against physical threats such as blast waves and explosion impacts.
Unlike the vast number of studies that focus on the environmental and recreational functions of green spaces, fewer investigations have examined their defensive and protective capacities in urban safety planning. The present study addresses this gap by evaluating different tree arrangement patterns in urban green spaces to identify the most effective layout for mitigating the impacts of explosions on buildings. The novelty of this research lies in linking landscape design and passive defense principles, providing practical insights for urban managers, landscape architects, and safety planners.
 
Methodology
 This study is applied and developmental in nature, employing a descriptive-survey approach. Initially, through a comprehensive literature review, key criteria related to tree arrangements were identified. Subsequently, expert judgment was sought to prioritize these criteria and assess alternative layouts. A total of 26 experts participated, representing fields such as architecture, urban planning, civil engineering, environmental science, urban management, and passive defense.
The research instrument was a two-part questionnaire: the first part focused on ranking the relative importance of criteria, while the second part evaluated alternative tree layouts based on these criteria. The four main criteria were defined as follows:
Resistance against explosion (C1)
Visual concealment (C2)
Fire spread potential (C3)
Economic considerations (C4)
To analyze the collected data, two multi-criteria decision-making (MCDM) methods were applied:
SWARA (Stepwise Weight Assessment Ratio Analysis) was used to determine the weights and prioritize the criteria based on expert judgment.
COPRAS (Complex Proportional Assessment) was then employed to rank six alternative tree arrangements: linear, irregular, dense, vertical, zigzag, and topographic-based layouts.
SWARA was selected for its simplicity and capacity to incorporate expert knowledge in weighting, while COPRAS enabled a comparative assessment of alternatives considering both beneficial and non-beneficial criteria.
 Discussion
The SWARA analysis revealed that “resistance against explosion” (C1) is the most significant criterion, accounting for approximately 40% of the total weight. This highlights the primacy of protective functions in the context of urban security. The second most important criterion was “fire spread” (C3) with about 29%, followed by “visual concealment” (C2) at 20% and “economic considerations” (C4) at 11%. Clearly, safety-related factors outweigh aesthetic or cost-related aspects when green space is designed for protective purposes.
Subsequent evaluation using COPRAS ranked the tree arrangements based on their effectiveness in mitigating explosion impacts. The results indicated that the dense arrangement achieved the highest score (21.1%), making it the most effective option for reducing blast effects on buildings. Its superiority is attributed to its ability to absorb and attenuate blast waves through compact vegetation layers. The topographic arrangement (17.5%) ranked second, benefitting from the synergy of vegetation with natural landforms that help disperse shockwaves.
Irregular (16.4%) and zigzag (16.1%) layouts performed moderately, providing partial deflection of blast energy but lacking the efficiency of dense vegetation. In contrast, the vertical (14.4%) and linear (14.1%) patterns scored the lowest, as their sparse coverage allows shockwaves to pass through with minimal resistance.
These findings align with international research, such as FEMA guidelines on secure site and urban design, which emphasize the role of landscaping and vegetation density in blast mitigation. They also support ecological studies highlighting the multifunctionality of urban green spaces when integrated into broader safety strategies.
Results
 The main outcomes of this research can be summarized as follows:
 

Resistance against explosion is the dominant criterion in tree arrangement for urban safety, followed by fire spread, visual concealment, and cost.
Dense tree arrangement is the most effective strategy for mitigating blast impacts on buildings.
Topographic-based arrangements also provide strong protection and can serve as a practical complementary strategy.
Irregular and zigzag patterns are acceptable alternatives but less efficient.
Vertical and linear layouts are the least effective and are not recommended for protective urban design.

Overall, the study underscores the necessity of rethinking urban green space planning from a security-oriented perspective. Designing dense vegetation buffers around sensitive and critical urban facilities, integrating them with topographic features, and aligning them with other passive defense measures can significantly reduce urban vulnerability to blast hazards. Such approaches not only enhance security but also strengthen the multifunctional role of green spaces, contributing to resilient, safe, and sustainable cities.
Conflict of Interest
Authors declared no conflict of interest.
 Acknowledgments
 We are grateful to all the scientific advisors and 
Keywords
Urban Green Space
Passive Defense
Explosion
Building
  1. Aghdaie, M. H., Hashemkhani Zolfani, S., & Zavadskas, E. K. (2013). Market segment evaluation and selection based on application of fuzzy AHP and COPRAS-G methods. Journal of Business Economics and Management, 14(1), 213–233.
  2. Bazazi, K., Ghods Vali, M., Shamsi, H., & Sotoudehnia, Y. (2018). Evaluation of spatial suitability of urban parks with a passive defense approach (Case study: Parks of Gorgan city). Golestan Scientific Quarterly of Police Knowledge, 9(36), 55–66.
  3. Bitarafan, M., Hosseini, S. B., Javad hashemi-fesharaki, S., & Esmailzadeh, A. (2013). Role of architectural space in blast-resistant buildings. Frontiers of Architectural Research, 2(1), 67-73.
  4. Bitarafan, M., Hosseini, S. B., Sabeti, N., & Bitarafan, A. (2016). The architectural evaluation of buildings’ indices in explosion crisis management. Alexandria Engineering Journal, 55(4), 3219-3228.
  5. Bitarafan, M., Zolfani, S. H., Arefi, S. L., & Zavadskas, E. K. (2012). Evaluating the construction methods of cold-formed steel structures in reconstructing the areas damaged in natural crises, using the methods AHP and COPRAS-G. Archives of civil and mechanical engineering, 12(3), 360-367.
  6. Chen, B., Adimo, O. A., & Bao, Z. (2009). Assessment of aesthetic quality and multiple functions of urban green space from the users’ perspective: The case of Hangzhou Flower Garden, China. Landscape and Urban Planning, 93(1), 76–82.
  7. Chen, W. Y., & Hu, F. Z. Y. (2015). Producing nature for public: Land-based urbanization and provision of public green spaces in China. Applied Geography, 58, 32–40.
  8. Federal Emergency Management Agency (FEMA). (2003). FEMA 426: Reference manual to mitigate potential terrorist attacks against buildings.
  9. Federal Emergency Management Agency (FEMA). (2003). FEMA 427: Primer for design of commercial buildings to mitigate terrorist attacks.
  10. Federal Emergency Management Agency (FEMA). (2005). FEMA 452: Risk assessment: A how-to guide to mitigate potential terrorist attacks against buildings.
  11. Federal Emergency Management Agency (FEMA). (2007). FEMA 430: Site and urban design for security: Guidance against potential terrorist attacks.
  12. Flores, A., Pickett, S. T. A., Zipperer, W. C., Pouyat, R. V., & Pirani, R. (1998). Adopting a modern ecological view of the metropolitan landscape: The case of a greenspace system for the New York City region. Landscape and Urban Planning, 39(4), 295–308.
  13. Georgi, J. N., & Dimitriou, D. (2010). The contribution of urban green spaces to the improvement of environment in cities: Case study of Chania, Greece. Building and Environment, 45(6), 1401–1414.
  14. Ginevičius, R., Suhajda, K., Petraškevičius, V., & Šimkūnaitė, J. (2014). Lithuanian experience of quantitative evaluation of socioeconomic systems position by multicriteria methods. Procedia - Social and Behavioral Sciences, 110, 952–960.
  15. Hashemkhani Zolfani, S., & Zavadskas, E. K. (2013). Sustainable development of rural areas’ building structures based on local climate. Procedia Engineering, 57, 1295–1301.
  16. Hashemkhani Zolfani, S., Esfahani, M. H., Bitarafan, M., Zavadskas, E. K., & Arefi, S. L. (2013). Developing a new hybrid MCDM method for selection of the optimal alternative of mechanical longitudinal ventilation of tunnel pollutants during automobile accidents. Transport, 28(1), 89–96.
  17. Hashemkhani Zolfani, S., Farrokhzad, M., & Turskis, Z. (2013). Investigating on successful factors of online games based on explorer. E & M Ekonomie a Management, 16(2), 161–169.
  18. Hashemkhani Zolfani, S., Rezaeiniya, N., Aghdaie, M. H., & Zavadskas, E. K. (2012). Quality control manager selection based on AHP-COPRAS-G methods: A case in Iran. Ekonomska Istraživanja, 25(1), 88–104.
  19. Hosseini, B., Bitarafan, M., Hosseini, B., & Hashemi-fesharak, J. (2013). Openings compatible with passive defense architecture by using Analytic hierarchy process (AHP). Journal of Architecture and Urban Planning, 6(11), 25-38.
  20. Hosseini, S. B., Bitarafan, M., Hashemi-Fesharaki, S. J., & Norouzian-Maleki, S. (2012). The role of basic forms buildings in explosion protection. International Journal of Science and Advanced Technology, 2(8), 47-50.
  21. Huang, D., Lu, C., & Wang, G. (2009). Integrated management of urban green space: The case in Guangzhou, China. 45th ISOCARP Congress Proceedings.
  22. Ighravwe, D. E., & Oke, S. A. (2019). An integrated approach of SWARA and fuzzy COPRAS for maintenance technicians’ selection factors ranking. International Journal of System Assurance Engineering and Management, 10, 1615–1626. https://doi.org/10.1007/s13198-019-00912-8
  23. Keršulienė, V., & Turskis, Z. (2014). An integrated multi-criteria group decision making process: Selection of the chief accountant. Procedia - Social and Behavioral Sciences, 110, 897–904.
  24. Li, M., Gong, F., Fu, J., She, M., & Zhu, H. (2011). The sustainable approach to the green space layout in high-density urban environment: A case study of Macau peninsula. Procedia Engineering, 21, 922–928.
  25. Maimaitiyiming, M., Ghulam, A., Tiyip, T., Pla, F., Latorre-Carmona, P., Halik, Ü., Sawut, M., & Caetano, M. (2014). Effects of green space spatial pattern on land surface temperature: Implications for sustainable urban planning and climate change adaptation. ISPRS Journal of Photogrammetry and Remote Sensing, 89, 59–66.
  26. Majnunian, H. (1995). Discussions on parks, green spaces, and recreation areas. Tehran: Tehran Parks and Green Space Organization Publications.
  27. Maroufi, A. R. (2011). Strategies and principles of green space design against threats from the perspective of passive defense (Master’s thesis). Malek Ashtar University of Technology, Tehran.
  28. Mathers, A., Dempsey, N., & Molin, J. F. (2015). Place-keeping in action: Evaluating the capacity of green space partnerships in England. Landscape and Urban Planning, 139, 126–136.
  29. Mishra, A. R., Rani, P., Pandey, K., Mardani, A., Streimikis, J., Streimikiene, D., & Alrasheedi, M. (2020). Novel multi-criteria intuitionistic fuzzy SWARA–COPRAS approach for sustainability evaluation of the bioenergy production process. Sustainability, 12(4155). https://doi.org/10.3390/su12104155
  30. Morales, S. J., Chalhoub, W., Mishra, A., Nigam, N., Alukal, J., Sultan, M. A., Haddad, N., & Carroll, J. E. (2015). Identification of risk factors for the development of distal esophageal stricture following radiofrequency ablation of Barrett's esophagus. Gastrointestinal Endoscopy, 81(5, Suppl), AB510.
  31. Nakhaei, J., Bitarafan, M., & Lale Arefi, S. (2015). Choosing the best urban tunnels as safe space in crisis using AHP method: a case study in Iran. Journal of Architecture and Urbanism, 39(2), 149-160.
  32. Nakhaei, J., Bitarafan, M., Lale Arefi, S., & Kapliński, O. (2016). Model for rapid assessment of vulnerability of office buildings to blast using SWARA and SMART methods (a case study of swiss re tower). Journal of Civil Engineering and Management, 22(6), 831-843.
  33. Nakhaei, J., Forghani, S., Bitarafan, M., Lale Arefi, S., & Šaparauskas, J. (2015). Reinforcement of laminated glass facades against the blast load. Journal of Civil Engineering and Management, 21(8), 1085-1097.
  34. Purirahim, A. A., Bitarafan, M., Arefi, S. L., & Setareh, A. A. (2012). Evaluation of Types of Buildings Entrances against Explosion. American Journal of Advanced Scientific Research (AJASR), 1(1).
  35. Rahim, A. A. P., Bitarafan, M., & Arefi, S. L. (2013). Evaluation of types of shapes of building roof against explosion. International Journal of Engineering and Technology, 5(1), 1.
  36. Rani, P., Mishra, A. R., Krishankumar, R., Mardani, A., Cavallaro, F., Ravichandran, K. S., & Balasubramanian, K. (2020). Hesitant fuzzy SWARA-complex proportional assessment approach for sustainable supplier selection (HF-SWARA-COPRAS). Symmetry, 12(1152). https://doi.org/10.3390/sym12071152
  37. Rostamkhani, P., & Loghaei, H. (2012). Principles of green space design in residential environments. Tehran: Building and Housing Research Center.
  38. Saaty, T. L., & Vargas, L. G. (2007). Dispersion of group judgments. Mathematical and Computer Modelling, 46(7–8), 918–925.
  39. Saeedi, A., Shiva, H., & Savadkouhi-Far, S. (2015). Passive defense considerations and environmental technologies in urban settlements (Case study: District 15). Scientific-Promotional Quarterly of Passive Defense, (23), 15–30.
  40. Seburanga, J. L., Kaplin, B. A., Zhang, Q.-X., & Gatesire, T. (2014). Amenity trees and green space structure in urban settlements of Kigali, Rwanda. Urban Forestry & Urban Greening, 13(1), 84–93.
  41. Threlfall, C. G., Walker, K., Williams, N. S. G., Hahs, A. K., Mata, L., Stork, N., & Livesley, S. J. (2015). The conservation value of urban green space habitats for Australian native bee communities. Biological Conservation, 187, 240–248.
  42. Wind, Y., & Saaty, T. L. (1980). Marketing applications of the analytic hierarchy process. Management Science, 26(7), 641–658.
  43. Zavadskas, E. K., Turskis, Z., Tamošaitienė, J., & Marina, V. (2008). Multicriteria selection of project managers by applying grey criteria. Technological and Economic Development of Economy, 14, 462–477.
  44. Zhang, B., Xie, G., Li, N., & Wang, S. (2015). Effect of urban green space changes on the role of rainwater runoff reduction in Beijing, China. Landscape and Urban Planning, 140, 8–16.
  45. Zhang, H., Chen, B., Sun, Z., & Bao, Z. (2013). Landscape perception and recreation needs in urban green space in Fuyang, Hangzhou, China. Urban Forestry & Urban Greening, 12(1), 44–52.