Determining aisle structures for facility designs using a hierarchy of algorithms

This paper introduces a tractable methodology for finding practical aisle structures for a facility for a given flexible bay block layout. The proposed methodology begins with a heuristic to identify candidate horizontal and vertical aisles using user guidance for the general form of the aisles. There then follows an enumeration algorithm that determines the final aisle structure. Using the calculated aisle structure, a non-linear programming model adjusts departmental areas and shapes to accommodate straight aisles. Finally, input/output points are sited using a genetic algorithm. Together, these algorithms specify a reasonable aisle structure and define the material flow through the facility. Two variations of the problem are solved-one with a limit on the total aisle distance and one with a cost per unit aisle length. The effectiveness of the proposed methodology is demonstrated on test problems with 20 and 50 departments.