Construction Equipment Management

John E. Schaufelberger, Giovanni C. Migliaccio

• Editore: Routledge
• Anno: 2019
• ISBN:
  9781351117449
• Edizione: 2
• Argomento: Architecture
• Categoria: Architecture Methods & Materials

This revised and updated edition of Construction Equipment Management fills a gap on this subject by integrating both conceptual and hands-on quantitative knowledge on construction equipment into a process that facilitates student learning.

The first six chapters summarize interdisciplinary concepts that are necessary to ground students' learning on construction equipment management, including both engineering and economics. Each of the next 16 chapters covers a different type of construction equipment and associated methods of use. The final chapter introduces the more advanced concept of operation analysis. This allows the book to be used on numerous courses at different levels to prepare graduates to apply skills on construction equipment when planning for a new project, estimating its costs, and monitoring field operations.

Organized around the major categories of construction equipment, including both commercial and heavy civil examples, case studies, and exercises, this textbook will help students develop independence in applying concepts to hands-on scenarios. A companion website provides an instructor manual, solutions, additional examples, lecture slides, figures, and diagrams.

1

INTRODUCTION

Importance of Construction Equipment

Construction equipment plays an important role in most construction projects. Whether it be to prepare the site, erect a building or bridge, or construct an airport runway, use of construction equipment is essential in completing construction projects. Commercial or residential contractors typically rely on renting or leasing equipment as needed, or they may choose to subcontract the work. However, because of repeated use of many major pieces of equipment, heavy civil construction contractors often find it more cost-effective to own their own equipment and treat their equipment fleet as a profit center for their companies. A contractor’s approach toward equipment is easily identifiable by reviewing their balance sheet, where equipment usually represents a large portion of the assets for heavy civil contractors and earthmoving specialty contractors. On the other hand, equipment ownership is modest among building contractors and homebuilders.

Decisions regarding the types and quantity of equipment to use on a project will greatly impact the project cost and duration. Consequently, the construction manager needs to select the equipment combination that yields the lowest production cost while achieving the desired productivity to enable meeting the contractual completion date. Thus, it is important for construction managers to understand the types of equipment used in construction, how they are used, safety considerations with their use, and how to estimate production costs.

Construction Equipment Management

Equipment is a critical resource in the execution of most construction projects. As the equipment fleet may represent the largest long-term capital investment in many construction companies, equipment management decisions have significant impacts on the economic viability of these construction firms. Equipment must pay for itself by earning more for the contractor than it costs to purchase, own, and use it. Idle equipment is a drain on income – operating costs are incurred only when the equipment is used, but ownership costs are incurred irrespective of frequency of use. Contractors must continually evaluate their equipment fleets to determine when to acquire additional items, when to replace items, and when to dispose of items that are underutilized.

One of the key decisions in planning and executing a construction project is the selection of equipment to use on the project. The type of equipment chosen will determine how the work will be done, the time required to complete the work, and the cost of construction. Therefore, it is important that construction managers understand what type of construction equipment is most appropriate for each construction task and how to estimate equipment productivity and costs. Success in construction is greatly influenced by the selection of equipment for the tasks to be performed.

The capabilities of construction equipment are described in manufacturers’ literature and can be used to estimate equipment productivity. The costs to be considered are the cost of owning, leasing, or renting the equipment and the costs of operating, maintaining, and repairing it. The effectiveness of a contractor’s preventive maintenance program will significantly influence equipment operating and repair costs.

Equipment Selection Factors

Most construction operations can be performed by more than one type of equipment. The equipment selected should complete the work in accordance with the project plans and specifications, in the required time frame, and at the least overall cost. The following factors should be considered in selecting equipment for a project:

• Cost-effectiveness. This means not only selecting the appropriate type of equipment for the task, but also selecting an appropriately sized machine.This involves comparison of the increased production rates of larger machines with their increased ownership and operating costs. Where possible, contractors should select the size of equipment that minimizes the unit cost (e.g., dollars per cubic yard) of performing the construction task.The soil conditions of the job site may dictate the type of equipment that should be selected. Tracked equipment usually is selected when the job site is soft or wet, because they exert less ground pressure and generally have better traction than wheeled equipment under such conditions. Construction site access or working area restrictions may limit the types and sizes of equipment that can be used on a construction site. The necessity to traverse highways will limit the use of off-highway equipment.

• Versatility. To control total project costs and minimize equipment transportation costs, equipment should be selected that can perform multiple tasks on a given project site. Using a dozer to excavate for a foundation, backfill the completed foundation, and carry out rough grading around the newly constructed building is usually more efficient than using a different type of equipment for each task. The project must be analyzed in its entirety to select the most cost-effective set of construction equipment to be used on the project.

The basic criteria that should be used in selecting equipment for specific tasks are:

• The capability of the equipment to perform the work

• The capability of the equipment to perform effectively under the working conditions of the job site

• The availability of the equipment, either from the contractor’s equipment fleet or from a rental or leasing agency

• The reliability of the equipment and predicted maintenance requirements

• The availability of parts and service support for the equipment

• The capability of the equipment to perform multiple tasks on the project

• Safety features available with the equipment

Selection involves the type and size of equipment, and its manufacturer. If the contractor owns a fleet of equipment, the choice might be limited to equipment that is available at the time needed. If the equipment is to be rented or leased, there may be a wider selection from which to choose. Generally, contractors select the set of equipment for a project that minimizes the unit cost (e.g., dollars per cubic yard) of performing the required work. Mobilization and demobilization costs also must be considered, and a set of multifunctional equipment might represent the best choice to minimize mobilization and demobilization costs.

Construction Equipment Utilization

Each piece of construction equipment is specifically designed by the manufacturer to perform specific mechanical operations. The job of the construction manager is to match the right piece of equipment or combination of equipment to the individual tasks to be performed in completing the project. One of the critical steps to determine the cost effectiveness of an equipment item is productivity estimation. Leading to equipment selection, this step is necessary to ensure that both cost and schedule implications are considered. Equipment production is work performed and is typically measured in volume, area, or linear length of work performed in a unit of time, such as an hour.

Although each major type of equipment has different operational characteristics, it is not always obvious which type of equipment is best suited to a particular project task. After studying the contract plans and specification, a soils report, and the project site, the construction manager must visualize how to employ specific pieces of equipment to accomplish the work. A quantity take-off is needed to determine the quantity of work to be performed, and an initial plan should be developed to prepare a list of equipment that will be needed for the project. Sometimes, multiple options need to be considered, and unit cost data developed for more than one option. Site conditions may limit the number of options that can be considered. For example, if excavated materials are to be transported off site over a highway, trucks will be needed because scrapers are not allowed to operate on highways.

Earthmoving tasks typically involve some combination of excavating, loading, hauling, spreading, compacting, and grading. Excavating can be performed with a dozer, a loader, an excavator, a front shovel, a clamshell, a dragline, or a scraper. The best choice depends on the work requirements of the project. The dozer can dig and push the excavated material out of the way. The scraper can load itself and haul the material away. Trucks can be loaded and used to haul the excavated material to a dump site. Loading is done with a loader, a shovel front, a clamshell, a dragline, or an excavator. Hauling is done either with trucks, haulers, or scrapers. Spreading usually is done by a scraper, dozer, or grader. Compacting is done with one of the many types of compactors manufactured. Grading is done with a grader.

The conditions of the project site and the haul distances often dictate the type of equipment to use. Because of its greater traction, tracked equipment is used where the site is wet. Equipment selection is based on an analysis of the haul distance, underfoot conditions, grades, material type, production rate, and operator skill. Distance is used as the basis for initial equipment selection. The economic haul distances (one way) for different types of mobile construction equipment are shown in Figure 1.1. The cross-hatched portions of the bars represent the most economical haul distances for the indicated systems. This figure can be used for initial selection of the appropriate type of hauling equipment.

FIGURE 1.1 Economic Haul Distance for Mobile Construction Equipment

(Courtesy of Caterpillar Inc.)

Once the type of equipment has been selected, the contractor must select the size to use. The alternatives may be limited by the contractor’s equipment fleet or what is available from a rental or leasing agency. Larger equipment generally has higher productivity than smaller models, but it also costs more to own or rent and operate. The labor costs generally are similar irrespective of the size of equipment selected, but the rental and other operating costs will increase with larger models. The contractor should attempt to select the size of equipment that will perform the required tasks at the least cost. This involves determining a unit cost for each activity, considering the equipment productivity and the hourly ownership or rental, operating, and labor costs.

Organization of This Book

The purpose of this book is to provide the student with (1) an understanding of the basic issues involved in construction equipment management and (2) an ability to estimate equipment productivity and cost. Concepts are discussed at the beginning of each chapter, followed by example problems illustrating the concepts introduced. A set of problems is provided at the end of most chapters to give students an opportunity to apply the concepts discussed.

Chapters 1 to 6 provide introductory concepts. Chapters 2, 3, and 4 are devoted to learning techniques for estimating equipment ownership and operating cost...