OPTIMIZATION OF CONSTRUCTION EQUIPMENT SELECTION FOR EARTHMOVING OPERATIONS

Abstract

Earthmoving operations are a major part of most of the water resources development projects and have long been the subject of investigations into estimating their output prior to actually commencing site work. Also the construction of many civil engineering projects, like highways, airports, buildings and industrial sites require the movement of earth and rock to alter the surface configuration or structural capacity of the ground. Different types of equipments have different productivity, so a construction operation can be carried out by a number of alternative equipments from different manufacturers. A problem which frequently confronts a construction manager as he plans to construct a project is the selection of the most suitable equipment. All types or sizes of equipment that might be used for the kind of work at construction site can be afforded. A suitable combination of equipments for a given earthmoving operation is often needed in practice in order to maximize the production or to minimize the cost. In general, earthmoving operation in most large construction projects is a major bid item which affects the overall cost and time of the project. In order for a contractor to win a job and to maximize profit, and for owner to minimize costs, accurate planning and estimating should be considered in this item. Careful selection of equipment, haul routes, and dumping points can yield to a significant saving in both time and cost. For small projects where a single loader and several trucks are required, equipment selection can be accomplished by simple deterministic methods that take in consideration the production rate and are constrained by the availability of equipment. While for large projects where multi loader-truck fleets are required, the selection process can be more complicated, and costs can vary severely. Determining the optimum size and number of equipments for an earthmoving operation is a task of critical importance because the variables affecting the equipment selection e.g. operation conditions, operation parameters, types of equipments available, required production rate, ownership costs, operating costs, etc are numerous. Proper earthmoving equipment selection, their optimum size and number is a major factor when trying to satisfy a project's, budget and scheduling requirements. In all cases, the objective is to maximize production, minimize the cost or maximize the profits. Normally the selection of equipment aims to minimize cost, maximize production, reduce the idle time of the equipment, work in a safe environment, and meet the requirement of the projects. The difficulty with production analysis in construction operations is that the variability in the components of the operations' cycles complicates the analysis. The presence of bunching of machines, equipment idle times, queues and other-non-deterministic events must be accounted for in any rational, analysis. Consequently, choosing between the different available equipment can be a complex task and an inexperienced person may fail to select the best fleet. In view of the above, as an attempt, the present dissertation provides optimization models for scrapers and haulers and outlines analytical development of these models taking into account the major factors that influence the output from the earthmoving operations. These models basically aim at determining the optimum size and number of these equipments for a given target of earthwork by taking into account the production of each type of equipment considered and the cost involved. Finally, all these models derive a Cost Index Number to select the proper equipment, its size and number/numbers. The models have been used to analyze the effect of various operating parameters on the performance of earthmoving operations particularly to the haulage of earth. The models have been developed through the programs written in C++ computer language. Various situations involving different operating parameters related to haulage can be analyzed by these models to optimize the earthmoving/hauling operations in real/site situations. In this dissertation an attempts has been made to cover some basic disciplines that affect the selection as well as the operation, efficiency, and the performance of earthmoving machinery. The most popular earthmoving machinery and their characteristics in relation to various factors affecting production have also been briefly discussed and a preamble.