CE 2353 - CONSTRUCTION PLANNING AND  SCHEDULING

UNIT-1

1.What is planning?  

Planning aims at formulation of a time based plan of action for coordinating various activities and resources to achieve specified objectives. Planning is the process of developing the project plan. The plan outlines how the project is to be directed to achieve the assigned goals. It specifies a predetermined and committed future course of action, based on discussions and decisions made on the current knowledge and estimation of future trends.  

2.What is construction planning?   

The construction planning process is stimulated through a study of project documents. These documents include but are not  limited to the available technical and commercial studies and investigations, designs and drawings, estimation of quantities,construction method statements, project planning data, contract documents, site conditions, market survey, local resources, project environment and the client’s organization. The planning process takes in to account, the strengths and weakness of the organizations.  

3.What are the objectives of planning? 

     Proper design of each element of the project 

     Proper selection of equipment and machinery in big projects, the use of large capacity plants are found economical 

     Procurement of materials well in advance 

     Proper arrangement of repair of equipment and machinery  

     Employment of trained and experienced staff on the project  

     To provide incentive for good workers

     To arrange constant flow of funds for the completion of project 

     To provide proper safety measures and ventilation, proper arrangement of light and water.  

4.What are the types of project plans?  

Planning the entire project from its inception to completion requires a vast coverage, varied skills and different types of plans. The nature of plans encountered in a typical construction project are indicated below    

Types of project plans  

 Development stage                                           nature of plan

 Inception stage                                                   project feasibility plan 

Engineering stage                                               project preliminary plan 

Implementation stage                                       project construction plan 

5.Define work tasks?  

Work tasks represent the necessary frame work to permit scheduling of construction activities, along with estimating the resources required by the individual work tasks and a necessary precedence or required sequence among the tasks. The terms work tasks or activities are often used interchangeably in construction plans to refer to specific defined items of work.

6.List out the project planning techniques?  

Stages	Planning process	Techniques/methods
1. Planning time	1.Breaking down project work, developing time network plans.	1.Work break down, network analysis,gnat chart.
2. Planning resources	2. Forecasting resource requirements, planning manpower requirements, planning material requirements, budgeting costs, designing organizational structure.	2. Man power scheduling Material scheduling Resource allocation Cost planning & budgeting Equipment selection and scheduling.
3. Planning implementation	3.Formulating monitoring methodology	3. Resource productivity control,time control, contribution control, budgetary control .

7.What are the steps involved in planning?  

a.defining the scope of  work to be performed 

b.preparing the logic or network diagram to establish a relationship among activities and integrating these diagrams to develop the network model  

c.analyzing the project network or models to determine project duration, and identifying critical and non-critical activities 

 d.Exploring trade-off between time to cost to arrive at optimal time and costs for completing the project.

e. Establishing standards for planning and controlling men, materials, equipment, costs and income of each work package 

f. Forecasting input resources, production costs and the value of the work done  

g. Forecasting the project budget allocations for achieving targets assigned to each organizational unit

 h. Designing a control system for the organization 

 i. Developing the resources, time and cost control methodology 

8. What is the purpose of coding?  

a. To identify the data connected with each work package, as work packages from the database for managing various project functions.

 b. To aid in the organization of data from the very detailed to the very broad levels 

c. To enable the processing, sorting, and extraction of information required at various levels of management and functional units. 

d. To computerize the data processing system  

9. How many categories available in codification?  

In construction projects, the codes used can be broadly divided in to two categories i.e. project interfacing codes or simply referred as project codes and department specialized codes.  

Project interface codes:  

These are the common codes used for developing an inter department database. Ex: a project code for the foundation of a building.  

Departmental specified codes: 

These codes are developed by the departmental heads for their use.    Ex: to indicate the location of materials in site ware houses  

10. Define the types of labeling approach?

 a. alphabet codes

b. numerical codes 

 c. alphanumeric codes  

Alphabet codes:   

 Alphabet letters A to Z, single or combined, can be used to represent a code. An alphabet in a single character space can represent 26 variations as compared to numerals 0 to 9, which can depict maximum of 10 variations  

Numerical codes:   

 It is the most important form of coding in numerical codes, each character can be represented by a numerical varying from 0 to 9  

Alpha numerical codes:  

 It is the combination of alphabets and numerals to develop a each code.  

11. Defining precedence relationship among activities?  

Precedence relations between activities signify that the activities must take place in a particular sequence.

Numerous natural sequences exist for construction activities due to requirements for structural integrity, regulations and  other technical requirements. 

For example  

  Excavate            place formwork         place reinforcement                   pour concrete                      Trench       

                                                                                                                                                                                              

12.Define the following terms?

 i.activity 

ii.event 

Activity: A project can be broken down in to various operations and process necessary for its completion. Each of these  operations and processes, which consume time and possibly resources, is called activity. The activities are represented by

arrows.  

For example:   

Excavation

2

Event: It is the state between the completion of a preceding activity and the beginning of the succeeding one. It has no duration an event is shown by a circle or ellipse      

                      

          1                           2

13. Define activity direct cost? 

   This is the cost that can be traced in full with the execution of a specific activity. It consists of costs of direct labour,direct equipment and other direct costs. For example: in the activity of roof concreting, the following direct costs would be involved.   

Types of costs                                                               item of costs

Direct materials                                                             cost of concrete and steel    

Direct labour                                                                 cost of labour employed  

14. Define activity indirect cost?

This is the cost that incurred while performing an activity, but cannot be traced directly to its execution. In other words, all costs other than the direct ones fall in this category. These represent the apportioned share of supervision general and administration costs are commonly refer to as overheads.        

16 MARK QUESTIONS

1.   What is Construction Planning? Explain the basic concepts in the development of Construction plans.                                                                                                                                                          Construction planning is a fundamental and challenging activity in the management and execution of construction  projects. It involves the choice of technology, the definition of work tasks, the estimation of the required resources and  durations for individual tasks, and the identification of any interactions among the different work tasks. A good construction  plan is the basis for developing the budget and the schedule for work. Developing the construction plan is a critical task in  the management of construction, even if the plan is not written or otherwise formally recorded. In addition to these  technical aspects of construction planning, it may also be necessary to make organizational decisions about the relationships  between project participants and even which organizations to include in a project. For example, the extent to which sub-contractors will be used on a project is often determined during construction planning.

   A planner begins with a result (i.e. a facility design) and must synthesize the steps required to yield this result. Essential aspects of construction planning include the generation of required activities, analysis of the implications of these activities,  and choice among the various alternative means of performing activities. In contrast to a detective discovering a single train  of events, however, construction planners also face the normative problem of choosing the best among numerous  alternative plans. A planner must imagine the final facility as described in the plans and specifications.

In developing a construction plan, it is common to adopt a primary emphasis on either cost control or on schedule  control. Some projects are primarily divided into expense categories with associated costs. In these cases, construction  planning is cost or expense oriented. Within the categories of expenditure, a distinction is made between costs incurred  directly in the performance of an activity and indirectly for the accomplishment of the project. For example, borrowing  expenses for project financing and overhead items are commonly treated as indirect costs. For other projects, scheduling of  work activities over time is critical and is emphasized in the planning process. In this case, the planner insures that the  proper precedences among activities are maintained and that efficient scheduling of the available resources prevails.

Traditional scheduling procedures emphasize the maintenance of task precedences (resulting in critical path scheduling  procedures) or efficient use of resources over time (resulting in job shop scheduling procedures). Finally, most complex projects require consideration of both cost and scheduling over time, so that planning, monitoring and record keeping must  consider both dimensions. In these cases, the integration of schedule and budget information is a major concern.   

Alternative Emphases in Construction Planning

 

 

                 

                                                                                                

Construction planning is not an activity which is restricted to the period after the award of a contract for construction.It should be an essential activity during the facility design. Also, if problems arise during construction, re-planning is required.  

2.   Explain briefly Choice of Construction Technology and Construction method?

 Choice of Construction Technology and Construction method

 As in the development of appropriate alternatives for facility design, choices of appropriate technology and methods  for construction are often ill-structured yet critical ingredients in the success of the project. For example, a decision whether  to pump or to transport concrete in buckets will directly affect the cost and duration of tasks involved in building  construction. A decision between these two alternatives should consider the relative costs, reliabilities, and availability of  equipment for the two transport methods. Unfortunately, the exact implications of different methods depend upon  numerous considerations for which information may be sketchy during the planning phase, such as the experience and  expertise of workers or the particular underground condition at a site.  

In selecting among alternative methods and technologies, it may be necessary to formulate a number of construction  plans based on alternative methods or assumptions. Once the full plan is available, then the cost, time and reliability impacts  of the alternative approaches can be reviewed. This examination of several alternatives is often made explicit in bidding  competitions in which several alternative designs may be proposed or value engineering for alternative construction  methods may be permitted. In this case, potential constructors may wish to prepare plans for each alternative design using  the suggested construction method as well as to prepare plans for alternative construction methods which would be  proposed as part of the value engineering process.  

In forming a construction plan, a useful approach is to simulate the construction process either in the imagination of  the planner or with a formal computer based simulation technique. By observing the result, comparisons among different  plans or problems with the existing plan can be identified. For example, a decision to use a particular piece of equipment for  an operation immediately leads to the question of whether or not there is sufficient access space for the equipment. Three  dimensional geometric models in a computer aided design (CAD) system may be helpful in simulating space requirements  for operations and for identifying any interferences. Similarly, problems in resource availability identified during the Construction planning Direst cost  Indirect cost  Time oriented (critical path problem) Resource oriented(job schop schedule) Schedule oriented Cost oriented simulation of the construction process might be effectively forestalled by providing additional resources as part of the construction plan.  

Example- Laser Leveling 

 An example of technology choice is the use of laser leveling equipment to improve the productivity of excavation and  grading. In these systems, laser surveying equipment is erected on a site so that the relative height of mobile equipment is  known exactly. This height measurement is accomplished by flashing a rotating laser light on a level plane across the  construction site and observing exactly where the light shines on receptors on mobile equipment such as graders. Since laser  light does not disperse appreciably, the height at which the laser shines anywhere on the construction site gives an accurate  indication of the height of a receptor on a piece of mobile equipment. In turn, the receptor height can be used to measure  the height of a blade, excavator bucket or other piece of equipment. Combined with electro-hydraulic control systems  mounted on mobile equipment such as bulldozers, graders and scrapers, the height of excavation and grading blades can be  precisely and automatically controlled in these systems. This automation of blade heights has reduced costs in some cases  by over 80% and improved quality in the finished product, as measured by the desired amount of excavation or the extent to  which a final grade achieves the desired angle. These systems also permit the use of smaller machines and less skilled  operators. However, the use of these semi-automated systems require investments in the laser surveying equipment as well  as modification to equipment to permit electronic feedback control units. Still, laser leveling appears to be an excellent  technological choice in many instances.  

3.   Explain coding systems 

One objective in many construction planning efforts is to define the plan within the constraints of a universal coding system for identifying activities. Each activity defined for a project would be identified by a pre-defined code specific to that

activity. The use of a common nomenclature or identification system is basically motivated by the desire for better integration of organizational efforts and improved information flow. In particular, coding systems are adopted to provide a numbering system to replace verbal descriptions of items. These codes reduce the length or complexity of the information to be recorded. A common coding system within an organization also aids consistency in definitions and categories between projects and among the various parties involved in a project. Common coding systems also aid in the retrieval of historical  records of cost, productivity and duration on particular activities. Finally, electronic data storage and retrieval operations are  much more efficient with standard coding systems.

  The most widely used standard coding system for constructed facilities is the MASTERFORMAT system developed by  the Construction Specifications Institute (CSI) of the United States and Construction Specifications of Canada. After  development of separate systems, this combined system was originally introduced as the Uniform Construction Index (UCI)  in 1972 and was subsequently adopted for use by numerous firms, information providers, professional societies and trade

organizations. The term MASTERFORMAT was introduced with the 1978 revision of the UCI codes. MASTERFORMAT  provides a standard identification code for nearly all the elements associated with building construction.MASTERFORMAT involves a hierarchical coding system with multiple levels plus keyword text descriptions of each item.In the numerical coding system, the first two digits represent one of the sixteen divisions for work; a seventeenth division is  used to code conditions of the contract for a constructor. In the latest version of the MASTERFORMAT, a third digit is added  to indicate a subdivision within each division. Each division is further specified by a three digit extension indicating another  level of subdivisions. In many cases, these subdivisions are further divided with an additional three digits to identify more  specific work items or materials. For example, the code 16-950-960, "Electrical Equipment Testing" are defined as within Division 16 (Electrical) and Sub-Division 950 (Testing). The keywords "Electrical Equipment Testing" is a standard description of the activity.While MASTERFORMAT provides a very useful means of organizing and communicating information, it has some  obvious limitations as a complete project coding system. First, more specific information such as location of work or  responsible organization might be required for project cost control. Code extensions are then added in addition to the digits  in the basic MASTERFORMAT codes. For example, a typical extended code might have the following elements:   

0534.02220.21.A.00.cf34  

The first four digits indicate the project for this activity; this code refers to an activity on project number 0534. The next five digits refer to the MASTERFORMAT secondary division; referring to Table 9-7, this activity would be 02220 "Excavating, Backfilling and Compacting." The next two digits refer to specific activities defined within this MASTERFORMAT code; the digits 21 in this example might refer to excavation of column footings. The next character refers to the block or general area on the site that the activity will take place; in this case, block A is indicated. The digits 00 could be replaced by a code to indicate the responsible organization for the activity. Finally, the characters cf34 refer to the particular design element  number for which this excavation is intended; in this case, column footing number 34 is intended. Thus, this activity is to  perform the excavation for column footing number 34 in block A on the site.   

4.    Discuss the various factors deciding the activity durations. 

In most scheduling procedures, each work activity has associated time duration. These durations are used extensively  in preparing a schedule. The entire set of activities would then require at least 3 days, since the activities follow one another  directly and require a total of 1.0 + 0.5 + 0.5 + 1.0 = 3 days. If another activity proceeded in parallel with this sequence, the 3  day minimum duration of these four activities is unaffected. More than 3 days would be required for the sequence if there  was a delay or a lag between the completion of one activity and the start of another.

    Durations and Predecessors for a Four Activity Project Illustration

Activity	Predecessor	Duration (Days)
Excavate trench	----	1.0
Place formwork	Excavate trench	0.5
Place reinforcing	Place formwork	0.5
Pour concrete	Place reinforcing	1.0

All formal scheduling procedures rely upon estimates of the durations of the various project activities as well as the  definitions of the predecessor relationships among tasks. The variability of an activity's duration may also be considered.  Formally, the probability distribution of an activity's duration as well as the expected or most likely duration may be used in  scheduling. A probability distribution indicates the chance that a particular activity duration will occur. In advance of actually  doing a particular task, we cannot be certain exactly how long the task will require.  A straightforward approach to the  estimation of activity durations is to keep historical records of particular activities and rely on the average durations from  this experience in making new duration estimates. Since the scope of activities are unlikely to be identical between different  projects, unit productivity rates are typically employed for this purpose. For example, the duration of an activity D ij  such as  concrete formwork assembly might be estimated as:   

                                                       D ij  =

Where A ij  is the required formwork area to assemble (in square yards), P ij  is the average productivity of a standard  crew in this task (measured in square yards per hour), and N ij  is the number of crews assigned to the task. In some  organizations, unit production time, T ij  , is defined as the time required to complete a unit of work by a standard crew 

                                              Learning phase             Steady state phase

                                   

 

                          

               Productivity

 

  Time

Random factors will also influence productivity rates and make estimation of activity durations uncertain. For example, a scheduler will typically not know at the time of making the initial schedule how skillful the crew and manager will  be that are assigned to a particular project. The productivity of a skilled designer may be many times that of an unskilled  engineer. In the absence of specific knowledge, the estimator can only use average values of productivity.

5.   Explain how precedence relationship among activities are defined. 

Precedence relations between activities signify that the activities must take place in a particular sequence.Numerous natural sequences exist for construction activities due to requirements for structural integrity, regulations, and  other technical requirements. For example, design drawings cannot be checked before they are drawn. Diagramatically,  precedence relationships can be illustrated by a network or graph in which the activities are represented by arrows . The  arrows in Figure are called branches or links in the activity network, while the circles marking the beginning or end of each  arrow are called nodes or events. In this figure, links represent particular activities, while the nodes represent milestone events.

  Excavate                    place formwork              place reinforcement                 pour concrete                 Trench       

   Excavate            place formwork         place reinforcement                   pour concrete                      Trench       

                                                                                                                                                                                              

Illustrative Set of Four Activities with Precedences

        More complicated precedence relationships can also be specified. For example, one activity might not be able to start  for several days after the completion of another activity. As a common example, concrete might have to cure (or set) for  several days before formwork is removed. This restriction on the removal of forms activity is called a lag between the  completion of one activity (i.e., pouring concrete in this case) and the start of another activity (i.e., removing formwork in  this case). Many computer based scheduling programs permit the use of a variety of precedence relationships.Three mistakes should be avoided in specifying predecessor relationships for construction plans. First, a circle of activity  precedences will result in an impossible plan. For example, if activity A precedes activity B, activity B precedes activity C, and  activity C precedes activity A, then the project can never be started or completed! Figure 9-4 illustrates the resulting activity  network. Fortunately, formal scheduling methods and good computer scheduling programs will find any such errors in the  logic of the construction plan.

A

                      

        C                        B                                               

                                                            

Example of an Impossible Work Plan

Finally, it is important to realize that different types of precedence relationships can be defined and that each has different  implications for the schedule of activities:  

     Some activities have a necessary technical or physical relationship that cannot be superseded. For example,concrete pours cannot proceed before formwork and reinforcement are in place.  

     Some activities have a necessary precedence relationship over a continuous space rather than as discrete work task  relationships. For example, formwork may be placed in the first part of an excavation trench even as the excavation equipment continues to work further along in the trench. Formwork placement cannot proceed further than the excavation, but the two activities can be started and stopped independently within this constraint.  

     Some "precedence relationships" are not technically necessary but are imposed due to implicit decisions within the  construction plan.

Unit 2

1.   What is the object of scheduling?. 

 Scheduling means putting the plan on calendar basis. A project network shows the sequence and inters dependencies of  activities, their time and their earliest and latest completion time, but these needs to be scheduled to determine  commencement and termination dates of each activity. Using optimum resources or working within resource constraints, it  is a time table of work. A basic distinction exists between resource oriented scheduling techniques. The project is divided  into number of operations.  

2. List out the advantages of scheduling.   

1. By studying of any work and the many alternative methods of execution, we can choose the best one. 

2. It gives a clear  idea regarding the required men, materials and equipments at different stages of work. 

3. Resource utilization is optimized. 

4. Actual progress of the work is monitored with the actual plan. If there is any delay, proper remedial measures can be  taken to avoid such delays.  

3. What is the purpose of work scheduling?   

The bar – chart type work schedule provides a simplified version of the work plan, which can easily be understood by all  concerned with planning, co – ordination, execution and control of the project. 

(b) It validates the time objectives:  

A work schedule shows the planned sequence of activities, data – wise while putting the work plan on a calendar basis, it  takes into account reduced efficiency of resources to adverse climatic conditions and other factors.

 ( c) It evaluates the implications of scheduling constraints:

A work schedule brings out the implications of constraints and enables preparation of a plan of work within the frame work  of these constraints. 

 4. What are the steps involved in schedule chart?   

(a) Select the EST point of activity layout on the graph, and draw a line sloping equal to its rate of execution i.e., 1 unit per  day. 

 (b) Plot the lowest rate slowing line and mark its intersection with the top to foundation horizontal line.  

( c ) Starting from the point of intersection, move forward horizontally on the top line and identify latest completion point of  subsequent activity as indicated by the set back.  

5. What are the factors affecting work scheduling? 

 (a) Time:  

Most of the projects carry time constraints in the form of imposed dates, these dates may include constraints on start and  completion of activities. 

(b) Manpower: 

 Man power is one of the main in the successful execution of projects. The idle labour time is paid for and the strikes and  breakdown of work are kept in view by manpower. 

  (c) Materials:   

Construction materials are increasingly becoming scarce and their procurement is a time consuming process. The schedule  aids in forecasting of materials and their timely supply determines the economics and progress work.

6. What is the purpose of numbering events? 

 i. It simplifies the identification and description of a n activity in terms of event numbers. 

ii. The activities are coded as i- j where i and j are the event numbers as commencement and termination of an activity.  

iii. It helps in developing identification code for computer application. 

 iv. It systematizes the computations of critical path for each activity as far as possible, the number of the proceeding event

it should be less than that of the succeeding event.  

7. Define the following terms:     

         1. Critical path:  

        The longest path through the network is called critical path and its length determines the minimum durations in which  the project can be completed.    

        2. PERT (Program Evaluation and Review Technique):  

        PERT is vent oriented. It is parabolistic model i.e., it takes into account uncertainties involved in the estimation time of a  job or an activity. It uses three estimates of the activity time, optimistic time and pessimistic time and, most likely time.     

        3. Dummy activity:  

        It is superimposed activity, which does not represent any specific operation or process. It has zero duration and  consumes no resources, its purpose is twofold.

 (a) To provide a logical link to maintain the correct.

 (b) To simplify the description of concurrent activities in terms of event numbers. The dummy activity is drawn like any  other activity, but with dotted lines. 

 8. What is the significance of critical path?    

        (a) It is the longest path in the network; however it is possible for a network to have more than one critical path. The  sum of the durations of critical activities along the critical path determines the duration of the project.

        (b). It is the most sensitive path, any change in duration critical activities along the critical path is bound to effect the  duration of the entire project.   

9. Define the following terms.      

         1. EST (Earliest Start Time):  

        This is the earliest time an activity can be started, assuming that all the activities prior to it have taken place as early as  possible.       

        2. LST (Latest Start Time) :  

        This is the latest time an activity can start consistent, with the completion of the project in the stipulated time. The LST  of an activity is determined by subtracting the activity duration from the LFT of succeeding event. 

         3. EFT (Earliest Finish Time):  

        It is the earliest time by which an activity can be completed assuming that all the activities prior to it begin at their EST.   

        4. LFT (Latest Finish Time):  

        It is the latest time by which an activity must be completed to ensure the completion of project within the stipulated  time.  

10. What are the classifications of networks?  

        1. Skeleton network   

        2. Master network  

        3. Detail network  

        4. Summary network. 

 11. Define the following terms:      

         (a) Float:   

The difference between the latest start time  and earliest start time of an activity is called as float. Float is a measure of the  amount of time by which the start of an activity can be delayed consistent with the completion of the project on time.      

        (b) Total Float:

        Total float of an activity is defined as the difference between the maximum duration of time available for the  completion and duration required to carry out that duration.  

12. What is mean by resource leveling and crashing?        

        Resource leveling: 

 The aim is reduce the peak resource requirements and smooth out period to period assignment within a constraint on the  project duration.       

        Crashing:   

Higher amounts of direct activity cost would be associated with smaller activity duration times, while longer duration time  would involve comparatively lower direct cost. Such deliberate reduction of activity times by putting in extra effort is called

Crashing.  

13. Define the following terms:       

1. Normal cost: 

           Normal cost is the lowest possible direct cost required to complete an activity.      

 2. Normal time: 

           Normal time is the maximum time required to complete an activity at normal cost.       

3. Crash time:            

        Crash time is the minimum possible time in which an activity can be completed using additional resources.       

4. Crash cost:            

        Crash cost is the direct cost i.e., anticipated in completing an activity within the crash time.  

14. Define activity cost slope.       

        Activity cost slope is the rate of increase in the cost of activity per unit with a decrease in time. The cost slope indicates  the additional cost incurred per unit of time saved in reducing the duration of an activity.

Activity Cost slope =              crash cost – Normal cost   .

                                                  Normal time – Crash time  

SIXTEEN  MARKS QUESTIONS

   1.Explain Critical path method with neat sketches.  

The most widely used scheduling technique is the critical path method (CPM) for scheduling, often referred to as critical  path scheduling. This method calculates the minimum completion time for a project along with the possible start and finish  times for the project activities. Indeed, many texts and managers regard critical path scheduling as the only usable and  practical scheduling procedure. Computer programs and algorithms for critical path scheduling are widely available and can

efficiently handle projects with thousands of activities.  

The critical path itself represents the set or sequence of predecessor/successor activities which will take the longest time to  complete. The duration of the critical path is the sum of the activities' durations along the path. Thus, the critical path can be  defined as the longest possible path through the "network" of project activities. The duration of the critical path represents

the minimum time required to complete a project. Any delays along the critical path would imply that additional time would  be required to complete the project. 

There may be more than one critical path among all the project activities, so completion of the entire project could be  delayed by delaying activities along any one of the critical paths. For example, a project consisting of two activities  performed in parallel that each require three days would have each activity critical for a completion in three days.

Formally, critical path scheduling assumes that a project has been divided into activities of fixed duration and well defined  predecessor relationships. A predecessor relationship implies that one activity must come before another in the schedule. No resource constraints other than those implied by precedence relationships are recognized in the simplest form of critical  path scheduling.     

An Activity-on-Branch Network for Critical Path Scheduling

An Activity-on-Node Network for Critical Path Scheduling

2.   Explain Activity float and schedules. 

A number of different activity schedules can be developed from the critical path scheduling procedure described in the  previous section. An earliest time schedule would be developed by starting each activity as soon as possible, at ES(i,j).  Similarly, a latest time schedule would delay the start of each activity as long as possible but still finish the project in the  minimum possible time. This late schedule can be developed by setting each activity's start time to LS(i,j). 

 Activities that have different early and late start times (i.e., ES(i,j) < LS(i,j)) can be scheduled to start anytime between ES(i,j)  and LS(i,j). The concept of float is to use part or all of this allowable range to schedule an activity without delaying the  completion of the project. An activity that has the earliest time for its predecessor and successor nodes differing by more  than its duration possesses a window in which it can be scheduled. That is, if E(i) + Dij < L(j), then some float is available in  which to schedule this activity.

 Float is a very valuable concept since it represents the scheduling flexibility or "maneuvering room" available to complete  particular tasks. Activities on the critical path do not provide any flexibility for scheduling nor leeway in case of problems. For  activities with some float, the actual starting time might be chosen to balance workloads over time, to correspond with  material deliveries, or to improve the project's cash flow.  

3.   Describe various methods of presenting project schedules. 

Communicating the project schedule is a vital ingredient in successful project management. A good presentation will greatly  ease the manager's problem of understanding the multitude of activities and their inter-relationships. Moreover, numerous  individuals and parties are involved in any project, and they have to understand their assignments. Graphical presentations  of project schedules are particularly useful since it is much easier to comprehend a graphical display of numerous pieces of  information than to sift through a large table of numbers. Early computer scheduling systems were particularly poor in this  regard since they produced pages and pages of numbers without aids to the manager for understanding them. It is  extremely tedious to read a table of activity numbers, durations, schedule times, and floats and thereby gain an  understanding and appreciation of a project schedule. In practice, producing diagrams manually has been a common  prescription to the lack of automated drafting facilities. Indeed, it has been common to use computer programs to perform  critical path scheduling and then to produce bar charts of detailed activity schedules and resource assignments manually.

With the availability of computer graphics, the cost and effort of producing graphical presentations has been significantly  reduced and the production of presentation aids can be automated.    Network diagrams for projects have already been introduced. These diagrams provide a powerful visualization of the  precedences and relationships among the various project activities. They are a basic means of communicating a project plan  among the participating planners and project monitors. Project planning is often conducted by producing network  representations of greater and greater refinement until the plan is satisfactory. 

An Example Bar Chart for a Nine Activity Project

Bar charts are particularly helpful for communicating the current state and schedule of activities on a project. As such, they  have found wide acceptance as a project representation tool in the field. For planning purposes, bar charts are not as useful  since they do not indicate the precedence relationships among activities. Thus, a planner must remember or record  separately that a change in one activity's schedule may require changes to successor activities. There have been various  schemes for mechanically linking activity bars to represent precedences, but it is now easier to use computer based tools to  represent such relationships.

5. Explain Scheduling with Resource Constraints and Precedence 

Two problems arise in developing a resource constrained project schedule. First, it is not necessarily the case that a critical  path schedule is feasible. Because one or more resources might be needed by numerous activities, it can easily be the case  that the shortest project duration identified by the critical path scheduling calculation is impossible. The difficulty arises  because critical path scheduling assumes that no resource availability problems or bottlenecks will arise. Finding a feasible  or possible schedule is the first problem in resource constrained scheduling. Of course, there may be a numerous possible  schedules which conform with time and resource constraints. As a second problem, it is also desirable to determine  schedules which have low costs or, ideally, the lowest cost.    Numerous heuristic methods have been suggested for resource constrained scheduling. Many begin from critical path  schedules which are modified in light of the resource constraints. Others begin in the opposite fashion by introducing  resource constraints and then imposing precedence constraints on the activities. Still others begin with a ranking or  classification of activities into priority groups for special attention in scheduling.One type of heuristic may be better than  another for different types of problems. Certainly, projects in which only an occasional resource constraint exists might be  best scheduled starting from a critical path schedule. At the other extreme, projects with numerous important resource  constraints might be best scheduled by considering critical resources first. A mixed approach would be to proceed  simultaneously considering precedence and resource constraints.   

A simple modification to critical path scheduling has been shown to be effective for a number of scheduling problems and is  simple to implement. For this heuristic procedure, critical path scheduling is applied initially. The result is the familiar set of  possible early and late start times for each activity. Scheduling each activity to begin at its earliest possible start time may  result in more than one activity requiring a particular resource at the same time. Hence, the initial schedule may not be  feasible. The heuristic proceeds by identifying cases in which activities compete for a resource and selecting one activity to  proceed. The start time of other activities are then shifted later in time. A simple rule for choosing which activity has priority  is to select the activity with the earliest CPM late start time (calculated as LS(i,j) = L(j)-Dij) among those activities which are  both feasible (in that all their precedence requirements are satisfied) and competing for the resource. This decision rule is  applied from the start of the project until the end for each type of resource in turn.

UNIT-III

1.   List out any 5 indirect cost. 

Temporary utility ,Cleaning  ,Unloading ,Ware housing ,Work shop 

2.   What is meant by Contigencies?              

        Contigency is a cushion of cost to deal with uncertainities.Few factors resulting in contigencies are minor design  changes,under estimate of cost,lack of experience,unanticipated price changes,safety problems etc. 

3.   What is meant by Budget?

         Budget is an estimate of cost planned to be spent to complete a particular activity. 

4. What are the types of cost flow? 

        1) Cash Inflow 

        2) Cash outflow 

5. What is meant by Cost Forecasting?

         Cost Forecasting is the requirement of cost to continue with the project at the desired speed. 

6.  What is meant by Cash Flow control?

        Cash Flow control is the additional planning required to arrange the cash to meet the demand for the funds. 

7.  What are the sources of cash inflow?

1.  Sales of goods,

2. Investment from the owner, 

3. Debt financing (loan),

4. Sales of shares 

8.  What are the sources of cash outflow?

1.  Purchase of shares,

2. Payment of dues on loan,

3. Payment of bills,

4.Taxes 

9.  List out the cost control problems

         Equipment rate variance 

        Equipment operating variance 

        Labour  rate variance 

        Material wastages 

        Equipment  variance 

        Other common reasons 

10. What are the project cost budget monitoring parameters?

         Budget cost of work Scheduled(BCWS) 

        Budget cost of work Performed(BCWP) 

        Actual cost of work Performed (ACWP) 

11. What are the methods of measuring progress of work?

         Ratio method 

        Repetitive type of work progress 

         Non Repetitive complexwork progress 

        Start/Finish method 

12. What are the types of accounting?

         1) Financial Accounting

         2) Cost Accounting 

13. What are the types of Assets?

         1) Current Assets 

        2) Liquid Assets 

        3) Fixed Assets

         4) Intangible Assets 

14. What are the types of Liabilities?

         1) Current Liabilities 

        2) Fixed Liabilities 

        3)

15. Give the hourly Productivity forecasting formula. 

                    C f =w*h f *u t 

 Where, 

         C f =Total units of work               

         W=Total units of work               

         h f =Time Per unit               

         u t =Cost per unit time 

16 MARKS QUESTIONS

1.  Explain Forecasting for Activity Cost Control 

For the purpose of project management and control, it is not sufficient to consider only the past record of costs and  revenues incurred in a project. Good managers should focus upon future revenues, future costs and technical problems. For  this purpose, traditional financial accounting schemes are not adequate to reflect the dynamic nature of a project. Accounts  typically focus on recording routine costs and past expenditures associated with activities. Generally, past expenditures  represent sunk costs that cannot be altered in the future and may or may not be relevant in the future. For example, after  the completion of some activity, it may be discovered that some quality flaw renders the work useless. Unfortunately, the  resources expended on the flawed construction will generally be sunk and cannot be recovered for re-construction  (although it may be possible to change the burden of who pays for these resources by financial withholding or charges;  owners will typically attempt to have constructors or designers pay for changes due to quality flaws). Since financial  accounts are historical in nature, some means of forecasting or projecting the future course of a project is essential for  management control.  

     Budgeted Cost

 The budgeted cost is derived from the detailed cost estimate prepared at the start of the project. The factors of cost would  be referenced by cost account and by a prose description.

•    Estimated total cost

 The estimated or forecast total cost in each category is the current best estimate of costs based on progress and any  changes since the budget was formed. Estimated total costs are the sum of cost to date, commitments and exposure.

Methods for estimating total costs are described below.  

     Cost Committed and Cost Exposure!!

 Estimated cost to completion in each category in divided into firm commitments and estimated additional cost or exposure.  Commitments may represent material orders or subcontracts for which firm dollar amounts have been committed.  

     Cost to Date

 The actual cost incurred to date is recorded in column 6 and can be derived from the financial record keeping accounts.  

     Over or (Under)

A final column in Table 12-4 indicates the amount over or under the budget for each category. This column is an indicator of  the extent of variance from the project budget; items with unusually large overruns would represent a particular managerial  concern. Note that variance is used in the terminology of project control to indicate a difference between budgeted and  actual expenditures. The term is defined and used quite differently in statistics or mathematical analysis.   

2.  Explain the types of Accounting systems. 

The cost accounts described in the previous sections provide only one of the various components in a financial accounting  system. Before further discussing the use of cost accounts in project control, the relationship of project and financial  accounting deserves mention. Accounting information is generally used for three distinct purposes:  

     Internal reporting to project managers for day-to-day planning, monitoring and control.  

     Internal reporting to managers for aiding strategic planning.  

     External reporting to owners, government, regulators and other outside parties.

External reports are constrained to particular forms and procedures by contractual reporting requirements or by generally  accepted accounting practices. Preparation of such external reports is referred to as financial accounting. In contrast, cost or  managerial accounting is intended to aid internal managers in their responsibilities of planning, monitoring and control.   Project costs are always included in the system of financial accounts associated with an organization. At the heart of this  system, all expense transactions are recorded in a general ledger. The general ledger of accounts forms the basis for  management reports on particular projects as well as the financial accounts for an entire organization. Other components of  a financial accounting system include:  

     The accounts payable journal is intended to provide records of bills received from vendors, material suppliers,  subcontractors and other outside parties. Invoices of charges are recorded in this system as are checks issued in  payment. Charges to individual cost accounts are relayed or posted to the General Ledger.  

     Accounts receivable journal provide the opposite function to that of accounts payable. In this journal, billings to  clients are recorded as well as receipts. Revenues received are relayed to the general ledger.  

     Job cost ledgers summarize the charges associated with particular projects, arranged in the various cost accounts  used for the project budget.  

     Inventory records are maintained to identify the amount of materials available at any time.  

In traditional bookkeeping systems, day to day transactions are first recorded in journals. With double-entry bookkeeping,  each transaction is recorded as both a debit and a credit to particular accounts in the ledger. For example, payment of a  supplier's bill represents a debit or increase to a project cost account and a credit or reduction to the company's cash  account. Periodically, the transaction information is summarized and transferred to ledger accounts. This process is called  posting, and may be done instantaneously or daily in computerized systems.

In reviewing accounting information, the concepts of flows and stocks should be kept in mind. Daily transactions typically  reflect flows of dollar amounts entering or leaving the organization. Similarly, use or receipt of particular materials represent  flows from or to inventory. An account balance represents the stock or cumulative amount of funds resulting from these  daily flows. Information on both flows and stocks are needed to give an accurate view of an organization's state. In addition,  forecasts of future changes are needed for effective management.  

3.  Explain cash flow control. 

Project managers also are involved with assessment of the overall status of the project, including the status of activities,  financing, payments and receipts. These components include costs incurred (as described above), billings and receipts for  billings to owners (for contractors), payable amounts to suppliers and contractors, financing plan cash flows (for bonds or  other financial instruments), etc. . 

In this case, costs are not divided into functional categories , such as labor, material, or equipment. Thus, the aggregation of  different kinds of cost exposure or cost commitment has not been performed. The elements  include:  

•Costs

 This is a summary of charges as reflected by the job cost accounts, including expenditures and estimated costs.  

•Billings

 This row summarizes the state of cash flows with respect to the owner of the facility; this row would not be included for  reports to owners.  

•Payables

 The Payables row summarizes the amount owed by the contractor to material suppliers, labor or sub-contractors.  

•Receivables

 This row summarizes the cash flow of receipts from the owner. Note that the actual receipts from the owner may differ  from the amounts billed due to delayed payments or retainage on the part of the owner.  

•Cash  Position

This row summarizes the cash position of the project as if all expenses and receipts for the project were combined in a  single account. Each of the rows shown in Table 12-8 would be derived from different sets of financial accounts. Additional  reports could be prepared on the financing cash flows for bonds or   

4.  Explain Schedule control 

Construction typically involves a deadline for work completion, so contractual agreements will force attention to schedules.  More generally, delays in construction represent additional costs due to late facility occupancy or other factors. Just as costs  incurred are compared to budgeted costs, actual activity durations may be compared to expected durations. In this process,  forecasting the time to complete particular activities may be required. 

 The methods used for forecasting completion times of activities are directly analogous to those used for cost forecasting.

For example, a typical estimating formula might be:  

 Where  D f  is the forecast duration, W is the amount of work, and h t  is the observed productivity to time t. As with cost  control, it is important to devise efficient and cost effective methods for gathering information on actual project  accomplishments. Generally, observations of work completed are made by inspectors and project managers and then work  completed is estimated. Once estimates of work complete and time expended on particular activities is available, deviations  from the original duration estimate can be estimated.  This figure is constructed by summing up the percentage of each activity which is complete at different points in time; this  summation can be weighted by the magnitude of effort associated with each activity. In Figure, the project was ahead of the  original schedule for a period including point A, but is now late at point B by an amount equal to the horizontal distance  between the planned progress and the actual progress observed to date.

Illustration of Planned versus Actual Progress over Time on a Project

 Schedule adherence and the current status of a project can also be represented on geometric models of a facility.   In evaluating schedule progress, it is important to bear in mind that some activities possess float or scheduling leeway, whereas delays in activities on the critical path will cause project delays. In particular, the delay in planned progress at time t may be soaked up in activities' float (thereby causing no overall delay in the project completion) or may cause a project  delay. As a result of this ambiguity, it is preferable to update the project schedule to devise an accurate portrayal of the  schedule adherence. After applying a scheduling algorithm, a new project schedule can be obtained.   

Illustration of Planned versus Actual Expenditures on a Project

5.  Explain the Project budget. 

For cost control on a project, the construction plan and the associated cash flow estimates can provide the baseline  reference for subsequent project monitoring and control. For schedules, progress on individual activities and the  achievement of milestone completions can be compared with the project schedule to monitor the progress of activities.  Contract and job specifications provide the criteria by which to assess and assure the required quality of construction. The  final or detailed cost estimate provides a baseline for the assessment of financial performance during the project. To the  extent that costs are within the detailed cost estimate, then the project is thought to be under financial control. Overruns in  particular cost categories signal the possibility of problems and give an indication of exactly what problems are being  encountered. Expense oriented construction planning and control focuses upon the categories included in the final cost  estimation. This focus is particular relevant for projects with few activities and considerable repetition such as grading and  paving roadways. 

 For control and monitoring purposes, the original detailed cost estimate is typically converted to a project budget, and the  project budget is used subsequently as a guide for management. Specific items in the detailed cost estimate become job  cost elements. Expenses incurred during the course of a project are recorded in specific job cost accounts to be compared  with the original cost estimates in each category. Thus, individual job cost accounts generally represent the basic unit for  cost control.

 Alternatively, job cost accounts may be disaggregated or divided into work elements which are related both to particular  scheduled activities and to particular cost account. In addition to cost amounts, information on material quantities and labor  inputs within each job account is also typically retained in the project budget. With this information, actual materials usage  and labor employed can be compared to the expected requirements. As a result, cost overruns or savings on particular items  can be identified as due to changes in unit prices, labor productivity or in the amount of material consumed.  

The number of cost accounts associated with a particular project can vary considerably. For constructors, on the order of  four hundred separate cost accounts might be used on a small project.  These accounts record all the transactions associated  with a project. Thus, separate accounts might exist for different types of materials, equipment use, payroll, project office,  etc. Both physical and non-physical resources are represented, including overhead items such as computer use or interest  charges.