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1、Quality Control 、Safety During Construction and Cost ControlQuality and Safety Concerns in ConstructionQuality control and safety represent increasingly important concerns for project managers. Defects or failures in constructed facilities can result in very large costs. Even with minor defects, re-

2、construction may be required and facility operations impaired. Increased costs and delays are the result. In the worse case, failures may cause personal injuries or fatalities. Accidents during the construction process can similarly result in personal injuries and large costs. Indirect costs of insu

3、rance, inspection and regulation are increasing rapidly due to these increased direct costs. Good project managers try to ensure that the job is done right the first time and that no major accidents occurs on the project. As with cost control, the most important decisions regarding the quality of a

4、completed facility are made during the design and planning stages rather than during construction. It is during these preliminary stages that component configurations, material specifications and functional performance are decided. Quality control during construction consists largely of insuring con

5、formance to these original design and planning decisions. While conformance to existing design decisions is the primary focus of quality control, these are exceptions to this rule. First, unforeseen circumstances, incorrect design decisions or changes desired by an owner in the facility function may

6、 require re-evaluation of design decisions during the course of construction. While these changes may be motivated by the concern for quality, they represent occasions for re-design with all the attendant objectives and constraints. As a second case, some designs rely upon informed and appropriate d

7、ecision making during the construction process itself. For example, some tunneling methods make decisions about the amount of shoring required at different locations based upon observation of soil conditions during the tunneling process. Since such decisions are based on better information concernin

8、g actual site conditions, the facility design may be more cost effective as a result. Any special case of re-design during construction requires the various considerations discussed. With the attention to conformance as the measure of quality during the construction process, the specification of qua

9、lity requirements in the design and contract documentation becomes extremely important. Quality requirements should be clear and verifiable, so that all parties in the project can understand the requirements for conformance. Safety during the construction project is also influenced in large part by

10、decisions made during the planning and design process. Some designs or construction plans are inherently difficult and dangerous to implement, whereas other, comparable plans may considerably reduce the possibility of accidents. For example, clear separation of traffic from construction zones during

11、 roadway rehabilitation can greatly reduce the possibility of accidental collisions. Beyond these design decisions, safety largely depends upon education, vigilance and cooperation during the construction process. Workers should be constantly alert to the possibilities of accidents and avoid taken u

12、nnecessary risks.Total Quality Control Quality control in construction typically involves insuring compliance with minimum standards of material and workmanship in order to insure the performance of the facility according to the design. These minimum standards are contained in the specifications. Fo

13、r the purpose of insuring compliance, random samples and statistical methods are commonly used as the basis for accepting or rejecting work completed and batches of materials. Rejection of a batch is based on non-conformance or violation of the relevant design specifications.An implicit assumption i

14、n these traditional quality control practices is the notion of an acceptable quality level which is a allowable fraction of defective items. Materials obtained from suppliers or work performed by an organization is inspected and passed as acceptable if the estimated defective percentage is within th

15、e acceptable quality level. Problems with materials or goods are corrected after delivery of the product.In contrast to this traditional approach of quality control is the goal of total quality control. In this system, no defective items are allowed anywhere in the construction process. While the ze

16、ro defects goal can never be permanently obtained, it provides a goal so that an organization is never satisfied with its quality control program even if defects are reduced by substantial amounts year after year. This concept and approach to quality control was first developed in manufacturing firm

17、s in Japan and Europe , but has since spread to many construction companies.Total quality control is a commitment to quality expressed in all parts of an organization and typically involves many elements. Design reviews to insure safe and effective construction procedures are a major element. Other

18、elements include extensive training for personnel, shifting the responsibility for detecting defects from quality control inspectors to workers, and continually maintaining equipment. Workers involvement in improved quality control is often formalized in quality circles in which groups of workers me

19、et regularly to make suggestions for quality improvement. Material suppliers are also required to insure zero defects in delivered goods. Initially, all materials from a supplier are inspected and batches of goods with any defective items are returned. Suppliers with good records can be certified an

20、d not subject to complete inspection subsequently.The traditional microeconomic view of quality control is that there is an “optimum” proportion of defective items. Trying to achieve greater quality than this optimum would substantially increase costs of inspection and reduce worker productivity. Ho

21、wever, many companies have found that commitment to total quality control has substantial economic benefits that had been unappreciated in traditional approaches. Expenses associated with inventory, rework, scrap and warranties were reduced. Worker enthusiasm and commitment improved. Customers often

22、 appreciated higher quality work and would pay a premium for good quality. As a result, improved quality control became a competitive advantages.Of course, total quality control is difficult to apply, particular in construction. The unique nature of each facility, the variability in the workforce, t

23、he multitude of subcontractors and the cost of marking necessary investments in education and procedures make programs of total quality control in construction difficult. Nevertheless, a commitment to improved quality even without endorsing the goal of zero defects can pay real dividends to organiza

24、tions.Safety Construction is a relatively hazardous undertaking. These are significantly more injuries and lost workdays due to injuries or illnesses in construction than in virtually any other industry. These work related injuries and illnesses are exceedingly costly. The Construction Industry Cost

25、 Effectiveness Project estimated that accidents cost $8.9 billion or nearly seven percent of the $ 137 billion （in 1979 dollars） spent annually for industrial, utility and commercial construction in the United States. Included in this total are direct costs （medical costs, premiums for workers compe

26、nsation benefits, liability and property losses） as well as indirect costs （reduced worker productivity, delays in projects, administrative time, and damage to equipment and the facility）. In contrast to most industrial accidents, innocent bystanders may also be injured by construction have resulted

27、 in fatalities to passerbys. Prudent project managers and owners would like to reduce accidents, injuries and illnesses as much as possible.As with all the other costs of construction, it is a mistake for owners to ignore a significant category of costs such as injury and illness. While contractors

28、may pay insurance premiums directly, these costs are reflected in bid prices or contract amounts. Delays caused by injuries and illnesses can present significant opportunity costs to owners. In the long run, the owners of constructed facilities must pay all the costs of construction. For the case of

29、 injuries and illnesses, this general principle might be slightly qualified since significant costs are borne by workers themselves or society at large. However, court judgments and insurance payments compensate for individual losses and ultimately borne by the owners. Various measures are available

30、 to improve jobsite safety in construction. Several of the most important occur before construction is undertaken. These include design, choice of technology and education. By altering facility designs, particular structures can be safer or more hazardous to construct. For example, parapets can be d

31、esigned to appropriate heights for construction worker safety, rather than the minimum height required by building codes.Choice of technology can also be critical in determining the safety of a jobsite. Safeguards built into machinery can notify operators of problems or prevent injuries. For example

32、, simple switches can prevent equipment from being operating when protective shields are not in place. With the availability of on-board electronics （including computer chips） and sensors, the possibilities for sophisticated machine controllers and monitors has greatly expanded for construction equi

33、pment and tools. Material and work process choices also influence the safety of construction. For example, substitution of alternative material for asbestos can reduce or eliminate the prospects of long term illnesses such as asbestosis.Educating workers and managers in proper procedures and hazards can have a direct impact on j