Locating mobile facilities in railway construction management

The location problem with mobile facilities is motivated by a real-life railway construction project. In railway construction, (im)mobile concrete batching facilities are located to build viaducts and tunnels on a line over a planning horizon. The problem is to determine the number and types of facilities to be located, to schedule the movement of mobile facilities, and to make concrete production-allocation decisions, so that all requirements are satisfied, facility capacities are not violated, and the total cost is minimized. To the best of our knowledge, such a problem has not been studied in the literature before. Two mathematical models and a preprocessing heuristic are developed to solve the problem. Computational results on the real case study problem and randomly generated test problem instances show that locational decisions are important in construction management

The dynamic p-median problem with mobile facilities

Being motivated by real life applications in construction management, we consider the dynamic p-median problem and its extension with mobile facilities. The number of facilities changes over a planning horizon where one or more facilities can be opened, relocated, or closed in any period. The problem is to determine (i) facility locations, (ii) opening/closing times of facilities, (iii) routes of mobile facilities, and (iv) demand allocations to open facilities such that the total cost is minimized. We present a mixed integer programming formulation of the dynamic p-median problem using discretization of distances to control the locational decision variables. We develop a branch and price algorithm and constructive heuristics to solve the problem. Extensive computational results of the solution method are provided on a set of test problem instances

A polynomial algorithm for the earthwork allocation problem with borrow and waste site selection

In road construction projects, earthwork is planned together with horizontal and vertical alignments. This study focuses on earthwork operations that basically include cutting the hills and filling the holes on the road path. The candidate borrow and waste sites can also be used to obtain or heap earth when the available cut and fill amounts are not balanced or operating these sites reduces the total earthwork cost. Total earthwork cost contains the transportation cost and the overall cost related to opening the candidate sites. The problem is to determine which borrow and waste sites to operate, and the earth flows between cut, fill, waste, and borrow sites such that the total cost is minimized. It is shown that the problem is a generalization of the well-known lot-sizing problem. A fixed charge network flow problem formulation is presented, and a polynomial time dynamic programming algorithm is developed for solving the problem

AN ADAPTIVE SIMULATED ANNEALING METHOD FOR TYPE-ONE SIMPLE ASSEMBLY LINE BALANCING: A REAL LIFE CASE STUDY

In this study, real life assembly line balancing problem of a dishwasher producer is addressed. The line considered is a multi-model assembly line and real life problem instance consists of approximately 300 tasks, 400 precedence relations and 70 stations per product model. The number of stations used to meet a specified production rate is desired to be minimized. To do this, a type-one simple assembly line balancing problem instance is considered for each product model. Due to thelarge size of the problem we could not find the optimal solution of the problem by mathematical programming methods. In order to find good solutions in short times an adaptive simulated annealing algorithm is developed. Performance of the algorithm is tested on several problem instances from the literature and found to be satisfactory. Then it is used to solve the real life problem instanceconsidered and a better solution than the current one is obtained