4.Labor,MaterialandEquipmentUtilization

1、4. Labor, Material and Equipment Utilization4.1 Factors Affecting Job-Site ProductivityJob-site productivity is influenced by many factors which can be characterized either as labor characteristics, project work conditions or as non-productive activities. The labor characteristics include:age, skill

2、 and experience of workforceleadership and motivation of workforceThe project work conditions include among other factors:Job size and complexity.Job site accessibility.Labor availability.Equipment utilization.Contractual agreements.Local climate.Local cultural characteristics, particularly in forei

3、gn operations.The non-productive activities associated with a project may or may not be paid by the owner, but they nevertheless take up potential labor resources which can otherwise be directed to the project. The non-productive activities include among other factors:Indirect labor required to main

4、tain the progress of the projectRework for correcting unsatisfactory workTemporary work stoppage due to inclement weather or material shortageTime off for union activitiesAbsentee time, including late start and early quitsNon-working holidaysStrikesEach category of factors affects the productive lab

5、or available to a project as well as the on-site labor efficiency.Labor CharacteristicsPerformance analysis is a common tool for assessing worker quality and contribution. Factors that might be evaluated include:Quality of Work - caliber of work produced or accomplished.Quantity of Work - volume of

6、acceptable workJob Knowledge - demonstrated knowledge of requirements, methods, techniques and skills involved in doing the job and in applying these to increase productivity.Related Work Knowledge - knowledge of effects of work upon other areas and knowledge of related areas which have influence on

7、 assigned work.Judgment - soundness of conclusions, decisions and actions.Initiative - ability to take effective action without being told.Resource Utilization - ability to delineate project needs and locate, plan and effectively use all resources available.Dependability - reliability in assuming an

8、d carrying out commitments and obligations. Analytical Ability - effectiveness in thinking through a problem and reaching sound conclusions.Communicative Ability - effectiveness in using orgal and written communications and in keeping subordinates, associates, superiors and others adequately informe

9、d. Interpersonal Skills - effectiveness in relating in an appropriate and productive manner to others.Ability to Work Under Pressure - ability to meet tight deadlines and adapt to changes.Security Sensitivity - ability to handle confidential information appropriately and to exercise care in safeguar

10、ding sensitive information.Safety Consciousness - has knowledge of good safety practices and demonstrates awareness of own personal safety and the safety of others.Profit and Cost Sensitivity - ability to seek out, generate and implement profit-making ideas.Planning Effectiveness - ability to antici

11、pate needs, forecast conditions, set goals and standards, plan and schedule work and measure results.Leadership - ability to develop in others the willingenss and desire to work towards common objectives.Delegating - effectiveness in delegating work appropriately.Development People - ability to sele

12、ct, train and appraise personnel, set standards of performance, and provide motivation to grow in their capacity. Diversity(Equal Employment Opportunity) - ability to be senstive to the needs of minorities, females and other protected groups and to demonstrate affirmative action in responding to the

13、se needs.These different factors could each be assessed on a three point scale: (1) recognized strength, (2) meets expectations, (3) area needing improvement. Examples of work performance in these areas might also be provided.Project Work ConditionsJob-site labor productivity can be estimated either

14、 for each craft (carpenter, bricklayer, etc.) or each type of construction (residential housing, processing plant, etc.) under a specific set of work conditions. A base labor productivity may be defined for a set of work conditions specified by the owner or contractor who wishes to observe and measu

15、re the labor performance over a period of time under such conditions. A labor productivity index may then be defined as the ratio of the job-site labor productivity under a different set of work conditions to the base labor productivity, and is a measure of the relative labor efficiency of a project

16、 under this new set of work conditions.The effects of various factors related to work conditions on a new project can be estimated in advance, some more accurately than others. For example, for very large construction projects, the labor productivity index tends to decreaseas the project size and/or

17、 complexity increase because of logistic problems and the learning that the work force must undergo before adjusting to the new environment. Job-site accessibility often may reduce the labor productivity index if the workers must perform their jobs in round about ways, such as avoiding traffic in re

18、paving the highway surface or maintaining the operation of a plant during renovation. Labor availability in the local market is another factor. Shortage of local labor will force the contractor to bring in non-local labor or schedule overtime work or both. In either case, the labor efficiency will b

19、e reduced in addition to incurring additional expenses. The degree of equipment utilization and mechanization of a construction project clearly will have direct bearing on job-site labor productivity. The contractual agreements play an important role in the utilization of union or non-union labor, t

20、he use of subcontractors and the degree of field supervision, all of which will impact job-site labor productivity. Since on-site construction essentially involves outdoor activities, the local climate will influence the efficiency of workers directly. In foreign operations, the cultural characteris

21、tics of the host country should be observed in assessing the labor efficiency.Non-Productive ActivitiesThe non-productive activities associated with a project should also be examined in order to examine the productive labor yield, which is defined as the ratio of direct labor hours devoted to the co

22、mpletion of a project to the potential labor hours. The direct labor hours are estimated on the basis of the best possible conditions at a job site by excluding all factors which may reduce the productive labor yield. For example, in the repaving of highway surface, the flagmen required to divert tr

23、affic represent indirect labor which does not contribute to the labor efficiency of the paving crew if the highway is closed to the traffic. Similarly, for large projects in remote areas, indirect labor may be used to provide housing and infrastructure for the workers hired to supply the direct labo

24、r for a project. The labor hours spent on rework to correct unsatisfactory original work represent extra time taken away from potential labor hours. The labor hours related to such activities must be deducted from the potential labor hours in order to obtain the actual productive labor yield.Example

25、 4-1: Effects of job size on productivityA contractor has established that under a set of standard work conditions for building construction, a job requiring 500,000 labor hours is considered standard in determining the base labor productivity. All other factors being the same, the labor productivit

26、y index will increase to 1.1 or 110% for a job requiring only 400,000 labor-hours. Assuming that a linear relation exists for the range between jobs requiring 300,000 to 700,000 labor hours as shown in Figure 4-1, determine the labor productivity index for a new job requiring 650,000 labor hours und

27、er otherwise the same set of work conditions.2 1 8 6 4 2 1 o o o o xapci-A-tinpol-dQqE-J7 、0.35002468Job Size (in 100,000 Labor Hours)Figure 4-1: Illustrative Relati on ship betwee n Productivity In dex and Job SizeThe labor productivity in dex I for the new job can be obta ined by lin ear in terpol

28、ati on of the available data as follows:500.000 -400,000= 0.85This implies that labor is 15% less productive on the large job tha n on the sta ndard project.Example 4-2: Productive labor yield 3In the con struct ion of an off-shore oil drilli ng platform, the pote ntial labor hours were found to be

29、L = 7.5 millio n hours. Of this total, the non-productive activities expressed in thousa nd labor hours were as follows:A = 417 for holidays and strikesB = 1,415 for absentees (i.e. vacation, sick time, etc.)C = 1,141 for temporary stoppage (i.e. weather, wait ing, union activities, etc.)D = 1,431 f

30、or in direct labor (i.e. build ing temporary facilities, clea ning up the site, rework to correct errors, etc.)Determ ine the productive labor yield after the above factors are take n into con siderati on.The perce ntages of time allocated to various non-productive activities, A, B, C and D are:A _L

31、417= 6%；E _LL415 _7,50019%7,500C1141D1.4317,500= 15%；L 7JC0= 12%The total perce ntage of time X for all non -productive activities is:疋二HD = 6%h-19% +15% +19% = 59%LThe productive labor yield, Y, whe n the give n factors for A, B, C and D are con sidered, is as follows:L-A-B-C-DL=100% -6%- 19% -15%

32、一 19% = 41%As a result, only 41% of the budgeted labor time was devoted directly to work on the facility.Example 4-3: Utilization of on-site workers timeAn example illustrati ng the effects of in direct labor requireme nts which limit productive labor by a typical craftsma n on the job site was give

33、 n by R. Tucker with the follow ing perce ntages of time allocati on: 4Productive time40%Un productive time20%Admi nistrative delays20%In efficie nt work methods15%Labor jurisdict ions and other work restrictio nsPers onal time 5%In this estimate, as much time is spent on productive work as on delay

34、s due to management and inefficiencies due to antiquated work methods.4.2 Material Procureme nt and DeliveryThe main sources of information for feedback and control of material procurement are requisitions, bids and quotati ons, purchase orders and subc on tracts, shipp ing and receiv ing docume nts

35、, and in voices. For projects involving the large scale use of critical resources, the owner may initiate the procurement procedure even before the selection of a constructor in order to avoid shortages and delays. Under ordinary circumstances, the constructor will handle the procurement to shop for

36、 materials with the best price/performance characteristics specified by the designer. Some overlapping and rehandling in the procurement process is unavoidable, but it should be minimized to insure timely delivery of the materials in good condition.The materials for delivery to and from a constructi

37、on site may be broadly classified as : (1) bulk materials, (2) standard off-the-shelf materials, and (3) fabricated members or units. The process of delivery, including transportation, field storage and installation will be different for these classes of materials. The equipment needed to handle and

38、 haul these classes of materials will also be different.Bulk materials refer to materials in their natural or semi-processed state, such as earthwork to be excavated, wet concrete mix, etc. which are usually encountered in large quantities in construction. Some bulk materials such as earthwork or gr

39、avels may be measured in bank (solid in site) volume. Obviously, the quantities of materials for delivery may be substantially different when expressed in different measures of volume, depending on the characteristics of such materials.Standard piping and valves are typical examples of standard off-

40、the-shelf materials which are used extensively in the chemical processing industry. Since standard off-the-shelf materials can easily be stockpiled, the delivery process is relatively simple.Fabricated members such as steel beams and columns for buildings are pre-processed in a shop to simplify the

41、field erection procedures. Welded or bolted connections are attached partially to the members which are cut to precise dimensions for adequate fit. Similarly, steel tanks and pressure vessels are often partly or fully fabricated before shipping to the field. In general, if the work can be done in th

42、e shop where working conditions can better be controlled, it is advisable to do so, provided that the fabricated members or units can be shipped to the construction site in a satisfactory manner at a reasonable cost.As a further step to simplify field assembly, an entire wall panel including plumbin

43、g and wiring or even an entire room may be prefabricated and shipped to the site. While the field labor is greatly reduced in such cases, materials for delivery are in fact manufactured products with value added by another type of labor. With modern means of transporting construction materials and f

44、abricated units, the percentages of costs on direct labor and materials for a project may cha nge if more prefabricated un its are in troduced in the con structi on process.In the con structi on in dustry, materials used by a specific craft are gen erally han dled by craftsme n, not by gen eral labo

45、r. Thus, electricians handle electrical materials, pipefitters handle pipe materials, etc. Thismultiple handlingdiverts scarce skilled craftsme n and con tractor supervisi on into activities which do not directly con tribute to con structi on. Si nee con tractors are not n ormally in the freight bus

46、 in ess, they do not perform the tasks of freight delivery efficie ntly. All these factors tend to exacerbate the problems of freight delivery for very large projects. Example 4-5: Freight delivery for the Alaska Pipeli ne Project7The freight delivery system for the Alaska pipeline project was set u

47、p to handle 600,000 tons of materials and supplies. This tonn age did not in clude the pipes which comprised ano ther 500,000 tons and were shipped through a differe nt routi ng system.The complexity of this delivery system is illustrated in Figure 4-2. The rectangular boxes denote geographical loca

48、tions. The points of origin represent plants and factories throughout the US and elsewhere. Some of the materials went to a primary staging point in Seattle and some went directly to Alaska. There were five ports of entry: Valdez, Anchorage, Whittier, Seward and Prudhoe Bay. There was a secondary st

49、aging area in Fairbanks and the pipeline itself was divided into six sections. Beyond the Yukon River, there was nothing available but a dirt road for hauling. The amounts of freight in thousands of tons shipped to and from various locations are indicated by the numbers near the network branches (wi

50、th arrows showing the directions of material flows) and the modes of transportation are noted above the branches. In each of the locations, the contractor had supervision and construction labor to identify materials, unload from transport, determine where the material was going, repackage if require

51、d to split shipments, and then re-load material on outgoing transport.Alaska Poirt of EntryFairbanksPifQliriGFigure 4-2: Freight Delivery for the Alaska Pipeli ne ProjectExample 4-6: Process pla nt equipme nt procureme nt8The procurement and delivery of bulk materials items such as piping electrical

52、 and structural elements involves a series of activities if such items are not standard and/or in stock. The times required for various activities in the procurement of such items might be estimated to be as follows:Requisiti on ready by desig ner00Owner approval55Inquiry issued to ven dors38Ven dor

53、 quotatio ns received1523Complete bid evaluati on by desig ner730Owner approval535Place purchase order540Receive prelimi nary shop draw ings1050Receive final desig n draw ings1060Fabrication and delivery60-200120-260ActivitiesDurati on( days)CumulativeDurati onAs a result, this type of equipme nt pr

54、ocureme nt will typically require four to nine mon ths. Slippage or con tracti on in this sta ndard schedule is also possible, based on such factors as the exte nt to which a fabricator is busy.4.3 Con structi on Equipme ntThe selecti on of the appropriate type and size of con structi on equipme nt

55、ofte n affects the required amount of time and effort and thus the job-site productivity of a project. It is therefore importa nt for site man agers and con structi on pla nners to be familiar with the characteristics of the major types of equipme nt most com mon ly used in con structi on. 9Excavati

56、 on and Load ingOne family of construction machines used for excavation is broadly classified as a crane-shovel as indicated by the variety of mach ines in Figure 4-3. The cran e-shovel con sists of three major comp onen ts:? a carrier or mounting which provides mobility and stability for the machin

57、e.? a revolving deck or turntable which contains the power and control units.? a front end attachment which serves the special functions in an operation.The type of mounting for all machines in Figure 4-3 is referred to as crawler mounting , which is particularly suitable for crawling over relatively rugged surfaces at a job site. Other types of mounting include truck mounting and wheel mounting which provide greater mobility between job sites, but require better surfaces for their operation. The revolving deck includes a cab to house the person opera