In this manuscript a new phenomenon of adjacency and closeness rating is proposed for constructing the optimal facility layout design. In the proposed approach, the closeness rating is applied to every pair of neighboring departments in a range of their attached point up to a predefined distance between them. Also, while in the traditional approach the closeness rating is applied for determining either the proximity or farness of two departments, the proposed approach considers both the degree of closeness as the economical purposes, and farness as the safety purposes concurrently. A mathematical model is proposed for constructing the optimal layout design. For evaluating the efficiency and flexibility of the proposed model, a computational experiment is conducted. Through the results of this experiment, three major novelties of the proposed model such as its flexibility for concurrent consideration of the economic and the safety aspects of the layout design, its ability for constructing varieties of the layout designs, and a better implementation of adjacency among the neighboring department's pairs during the designing processes are demonstrated. (C) 2016 Elsevier Ltd. All rights reserved.