City is a compact human habitat which due to the presence of human beings requires safety and security in all the physical, social, economic, cultural, and managerial dimensions. Any action that secures the human society, its natural and artificial environment, is considered passive defense if the approach is protection-based and the action, non-military. The issue of defensive urbanization and the role of passive defense in the life of the cities have been fundamental in urbanization studies and urban planning since ancient times. Attention to this issue in the Holy City of MASHHAD, as a religious metropolis and the spiritual capital of the nation with over 30 million pilgrims per year is very important.

The urban network could be considered an important vulnerable factor in urban areas which is in close relationship with securing escape space and safe places during air and land attacks of enemies and increasing the efficiency of rescue operations after crisis. The accessibility levels of a texture, in terms of both sheltering at the time of crisis, and during rescue, would have an effective role in increased/decreased number of casualties. Therefore, by designing an efficient communication network, the casualties could be reduced significantly.

This is a descriptive-analytic study; and data have been collected through library-survey methods. Considering the existing and available data, the passageways network of the study area (Zone 1, District 8 of Mashhad Municipality) has been examined based on two indicators, namely, the passageways to total ratio in terms of passageway width, and the pregnability level of the texture within the study area; and the vulnerability caused by the urban network inside that texture has been addressed. Examinations indicate the presence of inefficient urban network and high vulnerability levels of the study area in terms of passive defense.