Journal of Construction Engineering and Management

Although formwork based on high shoring towers is a very common solution for forming elevated slabs and other concrete elements over high spaces, the trade literature furnishes neither detailed guidelines nor basic cost data for the design of such formwork. The present paper presents a method for the design of elevated-slab formwork using scaffold-type towers as the vertical shoring element. The method includes the definition of a basic tower layout and its properties, an algorithm for determining the distances between the various elements of the formwork, and key information as a basis for economic evaluation of alternate design solutions. Whereas the algorithm directly solves a general case of a flat, nonconstrained slab, the method as a whole readily applies to elevated slabs and other high-rise concrete elements of any kind. The method has been found particularly useful when computerized. It may become even more important when incorporated into an intelligent design system that will take into account shape and load constraints exerted by particular cases.

In the United States, the Occupational Safety and Health Administration (OSHA) was created to enhance safety in the workplace. Employers are subject to OSHA site inspections and must conform to a set of comprehensive rules and regulations. In contrast, in a developing country such as India, comprehensive and universal safety regulations have not been developed. Workers are generally unskilled or semiskilled, poorly paid, temporarily employed, exhibit low production (productivity) rates, and often migrate in a group from one place to another in search of work. Typically, laborers are not trained in safe work practices, and there tends to be a lack of management commitment to safety programs and various safety procedures. In contrast, in a newly developed country such as Taiwan, the owner and the contractor are assigned joint responsibility for claims resulting from occupational accidents. A basic safety-control system, emphasizing the establishment of a safety committee and self inspection, has been developed to control project safety. This system may be universally applicable to both developed and developing regions.

Settlements occurring during the first phase of tunneling for the extension of the Docklands Light Railway in London caused concern for damage to the Mansion House during subsequent phases of the work. The building is a landmark structure and no further damage could be accepted. Tunneling was halted until a satisfactory protection program was in place. Various means of protecting the structure were investigated, ranging from full structural underpinning to a least-risk methodology based on the observational method. This paper describes the background to the development and implementation of the observational method to successfully protect the building and complete construction. This required appropriate contingency measures to be identified and planned in advance. Of the contingencies involving preventive or strengthening works, a system of structural ties through the building was selected as most appropriate, least risky, and most economical. Trigger levels for building response were established. Extensive instrumentation was installed and the building was fully monitored during the subsequent phases of tunneling.

In today's highway construction industry, the focus has shifted from building new transportation facilities to resurfacing, rehabilitating and restoring (3R's) those already in existence. These types of projects create a serious disruption in the normal flow of traffic resulting in a major inconvenience to the traveling public. Reducing construction time, thereby mitigating this inconvenience, has become a major emphasis for state highway agencies throughout the United States. In the past few years, several innovative contracting methods have been introduced into the highway construction industry. The basic concept of these innovative techniques is the motivation they provide encouraging the contractor to work faster, schedule accurately, and manage the construction process better. Results from the research conducted by the writers indicate that recent transportation projects constructed utilizing these innovative contracting methods have been very successful in reducing construction time, while only increasing overall construction costs minimally, if at all. This paper examines the advantages and disadvantages of these methods analyzing data obtained from various case studies throughout the United States and abroad.

This paper is concerned with the role of equity and level of equity investment required in a build-operate-transfer (BOT) tender. In times of decreasing ability to raise public funds for infrastructure projects, the BOT concept has been used increasingly by governments to implement privately financed projects such as toll roads and private power plants. This paper shows that high level of equity is necessary in BOT tender if it is specified in the request for proposal, the competition is keen, and financing for the project is uncertain. Governments are often concerned about the high financial charges that may overburden the cash flows of the project and which may subsequently affect the efficient running of the project. It may also be concerned about the availability of debt financing. Governments therefore view high equity as important and necessary. The threshold equity level proposed by the promoters must therefore be high—typically between 20% and 30%—for them to be short-listed and to proceed to the final round of negotiation when the selection will be made. Otherwise they will be dropped from further consideration.

This paper details, in quantitative terms, the effects of changes and change orders on labor productivity and efficiency. Data for the analyses were daily productivity values from three industrial projects constructed in the 1989–1992 time frame. A total of 522 workdays of data were collected. None of the data involved disputed work or contract claims. Various analysis techniques were applied to the data, including data sorts and averages, analysis of variance tests, and multiple regression. The results confirm that it is possible to perform changes without negatively impacting labor efficiency. There was no negative effect in fewer than half the days when changes were performed. However, the average effect of all changes was a 30% loss of efficiency. Investigations into the cause of efficiency losses showed that there were disruptions when changes work was performed. A regression analysis showed a 25–50% loss of efficiency depending on the type of disruption. A threefold increase in the number of material availability problems was the most obvious disruption associated with change work.

Construction projects are characterized by the random nature of the conditions under which they are implemented and by the dynamic use of available resources. Since site conditions vary randomly and resources perform a multitude of functions on various work tasks, planning of construction projects using traditional tools like the critical path method becomes limited and induces deficiency in the resulting plan. This paper demonstrates that a simulation-based methodology is appropriate for modeling such a scenario. The hierarchical simulation modeling (HSM) method, a simulation-based method, for planning of construction projects is presented. HSM enhances and combines the concepts of work breakdown structure and process modeling to arrive at an advanced framework for planning. Hierarchical and modular simulation constructs form the basis of this method. The construction of a bridge (Peace River Bridge) is used to illustrate HSM concepts and its advantages.

The two main components in the tender of a privatized infrastructure project let under the build-operate-transfer (BOT) contractual arrangement are the technical design and the financial package. This paper examines the impact of a financial package when assessed against the technical design during the selection process. It is concluded that the ability to provide an attractive financial package is critical under the conditions when (1) the project is technically certain; (2) the tolls to be charged are of government's main concern; (3) competition is keen; and (4) the project viability and financing are uncertain. However, promoters must not underestimate the importance of an innovative technical solution as it could make an attractive financial package possible. The role of an innovative technical solution was never in question in the cases studied in spite of the great importance attached to the financial package by the governments.

Preproject planning is defined as the process of developing sufficient strategic information for owners to address risk and decide whether to commit resources to maximize the change for a successful capital facility project. Preproject planning—also known as feasibility analysis, conceptual planning, and front-end planning—is at the interface between business and engineering. It is an owner's responsibility that it be performed adequately; however, many preproject-planning functions are performed by engineering consultants. Members of the engineering profession must be aware of its implications and requirements. This article presents results from an on-going investigation of preproject planning. The concept and definition of preproject planning are discussed. A validated process map describing the major subprocesses of preproject planning is presented and a brief narrative describing each is given. Key preproject-planning principles discovered during the course of the research project are outlined and conclusions concerning the preproject planning process are presented.

This paper, written for the ASCE Manual of Professional Practice for Quality in the Constructed Project, Volume II , presents an overview of the construction industry. The paper is organized in accordance with the recommendations of the Task Committee on Technical Supplements to the Guide. It provides a brief history of the development of the construction industry in the United States and its role in today's society. It describes how the industry is presently organized and functions and the types of construction companies. The paper discusses the various forms of construction contracts including: lump sum, unit price, guaranteed maximum price, cost reimbursable, construction management, and design construct. Important contract provisions are reviewed including: bonding, insurance and indemnification, changed conditions, change orders, schedule, liquidated damages, bonus and penalty provisions, payment terms and retainage, subcontracting, partnering and alternate dispute resolution. The writer explains how construction companies are organized, both in the main office and the field. The elements of construction engineering practice are explained and the qualifications for engineers in construction are presented. The relationships with other civil engineering disciplines and design professionals are discussed.