A precedence arrow from activity 140 to activity 150 would also remove the conﬂict by requiring that pile driving on abutment #2 be completed before pouring footing #1. The owner or architect-engineer may decide to add additional work or change certain contract requirements. It is standard practice, as well as being a requirement of some computer programs, that precedence diagrams start with a single opening activity and 71 72 4 Project Planning 10 Order & deliver piles 50 60 Drive piles Fine grade 20 Excavate 0 80 90 100 110 Place rebar Pour concrete Strip forms Finish Start 30 70 Build forms Place forms 40 Order & deliver rebar Figure 4.1 Concrete footing, precedence diagram conclude with a single closing activity. The job overhead amount of $69,868.40 was compiled using an estimated project duration of 15 weeks (from Section 3.9). In the ﬁrst project meeting, all the items discussed are classiﬁed as new business and numbered 1.1, 1.2, and so on. The purchase order should state that the job site is to be given at least 48 hours notice of a delivery so that adequate preparation can be made at the site for off-loading, inspecting, storing, or directly installing the material. Although such meetings can and do serve as a forum for a variety of job topics, the time status of construction operations is always a major consideration at such sessions. Where major equipment items are involved, a common procedure is to have the equipment supervisor make out daily or weekly equipment time cards, which include each equipment item on the job. With the activity number from the diagram, the schedule dates and ﬂoat values are quickly found from the corresponding activity number in this sort listing. It is not unusual for the owner to provide certain materials to the contractor for use on the project, although this does not occur on the highway bridge. 239 240 Weekly Labor Cost Report Project Week ending Cost Code (1) 31220.10.3 31222.10.3 31350.00.3 31361.10.3 03150.10.3 03150.20.3 03157.10.3 03159.10.3 03157.20.3 03311.10.3 Project No. It will determine how materials will ﬂow through the assembly area. Second, the LS of activity 50 is 22. Frequently, convention, together with experience and equipment availability, prescribes most of these choices to the estimator. 6.9 Planning for Quality In today’s construction market, every project needs to have a formalized quality control system in order to be competitive. Such a system constitutes an effective early-warning device for detecting when and where the project may be falling behind schedule. A diagram of this type is a simple and effective medium for communicating complex job interdependencies. 21 22 2 Management System The heart of CPM is a graphical job plan that shows all the construction activities necessary for job completion and the order in which they will be done. Management requires timely cost and production information for effective project cost control, and estimators need equipment productivity data to estimate the costs of future work. This section explores several industry standard presentation formats and the information and audiences they target. These actions constitute the monitoring and rescheduling phases of the time management system and are the subjects of discussion in this chapter. The hourly wage rates of various labor categories are immediately determinable, usually from applicable labor contracts, prescribed prevailing wage rates, or established area practice. The best evidence now available indicates that 70 working days actually will be required unless the job is expedited. Scheduling software can provide timely management information in an easily understood and immediately usable form. Construction Progress Chart Project Job No. 2.17 Example Project The Example Project involves the construction of an earth dam and some appurtenant structures. The effectiveness of corrective procedures depends largely on the ingenuity, resourcefulness, and energy of the people involved. If the same crane is required by two activities, an equipment restraint is imposed by having the start of one activity depend on the ﬁnish of the other. 1.10 Combined Bidding and Negotiation An owner sometimes will combine elements of both competitive bidding and negotiation. Or the owner may choose to subcontract the entire project, assuming the responsibility of coordinating and supervising the work of the subcontractors. The project cost code for the highway bridge is typical of systems widely used by contractors. At regular intervals, the stage of project advancement is observed and reported. Accrued income and cash receipts are equal in value, but as in the case of accrued costs and cash disbursements, their timing is different. The labor costs in these two reports are direct labor costs only and do not include indirect labor costs. This section is concerned with the ﬁrst of these two categories, generally referred to as the impacted baseline schedule. The updated project schedule shows this work to begin August 2, which is a Monday. When payment is made for the labor and materials, these are cash disbursements. Nevertheless, all project costs must be summarized and reported at regular intervals, monthly being common. Check for safety hazards and provide for waste disposal. III. The prime contractor might consider subcontracting that part of the work to a ﬁrm whose labor crews or equipment would be available at an earlier date than its own. The calculations proceed backward through the network, event by event, until TL values have been obtained for each event. This procedure, called front-end loading, serves to help to reimburse the contractor for its initial costs of moving in, setting up, and commencing operations. When the job is being priced, the estimator must exert every effort to price each work type as realistically as possible. �N��W���z?� �k��`9�h The new critical path is ﬁve days longer than the previous one (64 working days), so project completion is now delayed by ﬁve days, making a construction period (not including contingency) of 69 working days. Ample provision must be made for the delivery interval, with a safety factor present to allow for unforeseen delays, such as the required resubmittal of corrected shop drawings to the architect-engineer. There is no such adjustment for early-ﬁnish dates. 1. In such circumstances, both parties may become preoccupied 12.6 But-for or Collapsed As-Built Schedule with the question of the appropriateness of using the baseline schedule, preventing advancement of the larger delay issue. To illustrate, bar charts often have a category called ‘‘Electrical’’ or ‘‘Mechanical’’ whose bar extends from project start to ﬁnish. This reengineering process can be applied to any part of the project, from the way a piece of equipment is installed to the way change orders are handled. A good working relationship with a variety of outside persons and organizations, such as architects, engineers, owners, subcontractors, material and equipment dealers, labor unions, and regulatory agencies, is an important part of guiding a job through to its conclusion. .’’ Inspect the work space. This is sometimes accomplished by including a subcontract requirement that the subcontractor submit unpriced copies of its purchase orders to the general contractor within 10 days after receipt of the subcontract. The actual work quantities and labor costs to date are cumulative totals for each work classiﬁcation obtained from the time cards and weekly quantity reports. This policy can materially assist in controlling underusage of equipment. Plotting these on the ﬁgure discloses that these 18 activities form a continuous path from project beginning to project end; this chain of critical activities is called the critical path. Some prefer to charge it directly to the work classiﬁcations on which the supervisor spent time. Computation of ES. This procedure provides detailed information concerning the current time status of individual job segments. The original cost estimate and project schedule provide the basic cost and time information needed to make a cash disbursement forecast. Figure 8.2 is the labor summary for this project. Usually the contractor either will request no extra time or will request an extension equal to the full time required 11.18 Claims to accomplish the extra work itself. The ﬂowchart in Figure 2.1 depicts the overall Example Project and the principal operations that will be covered by the construction contract. The logical limit of a given critical activity is equal to the total ﬂoat of the shortest alternative path around that activity. The detail used in cost reporting is adjusted according to the level of management for which it is intended. It should be noted 8.10 Labor Leveling in Practice that activity 80, which can start as early as day 4 based on the network logic, has been allowed to slip to day 14 in order to maintain resource levels. The total development of a project normally consists of several phases requiring a diverse range of specialized services.