Wednesday 16 February 2022

Time-based project management


Project time (duration) management is aimed at planning, monitoring, adjusting, analyzing the timing and reserves of work in order to complete the project in a timely manner.

Time management implies:

· distribution of project implementation time by successive stages of its implementation;

· scheduling the implementation of the project and its individual works, and

· monitoring their compliance.

To implement the project within the framework of predetermined calendar deadlines, budgets, in compliance with the required indicators of product quality is much easier in words than in practice. Project implementation management in modern conditions is associated with a large share of uncertainty that does not depend on the project manager.

The project consists of a large number of diverse activities, such as various meetings and meetings, preparation of reports, interaction with the consumer and much more. The success of individual activities included in the project, and the project as a whole, is determined by the ability of the project manager to manage the time of his and his subordinates.

For most people, time is a resource (an irreplaceable resource). For the project manager, time is primarily a limitation, and only the skillful implementation of time management functions ensures the use of time as a kind of resource.

It is important to have an understanding of the factors of time loss. During the implementation of the project, the loss of time is expressed in:

· additional time spent on rescheduling the schedule of work. This may be due to the following reasons:

- errors were made by key project participants at the stage of determining the content of the work, expressed in the failure to take into account some of the objectives of the project, inaccuracies in the definition of project participants, the main milestones in the implementation of the project and the development of SDR;

- the planning process is based on incomplete data;

- little time is given to evaluate the performance of the project;

- historical data and previous experience are not taken into account when performing assessments;

- scheduling is carried out exclusively by the planning team, while those who will carry out the schedule should be actively involved in this process;

- resource requirements are not properly planned;

- risks are not taken into account when planning the work schedule;

- the actual state of the project is not reflected in the current schedule of work. This may be due to the fuzzy organization of the exchange of information between the performers and the project office, with the fact that when problems arise, people can panic and generally forget about the existence of the plan. As a result, discrepancies between the current and baseline work schedules are not tracked, the decisions necessary for the project are not made - "the plan and the project exist separately from each other";

· elimination of marriage. Loss of time to eliminate defects arises as a result of performing work not in accordance with quality requirements, for example, when using unqualified human resources or their excessive loading, low-quality materials, etc .;

· downtime/delay in the performance of work, which is primarily due to the lack of conditions for their implementation. This can be expressed in non-working weather conditions, interruptions in the supply of materials or equipment due to the fault of suppliers, etc.

Project time management includes the processes necessary and sufficient to ensure the timely completion of the project:

1. definition of works;

2. determination of the sequence of works;

3. estimation of the duration of work;

4. development of a calendar plan;

5. optimization and control of the calendar plan.

Let us consider in more detail the essence of these processes.

1. Definition of works. The process of defining work begins at the planning stage, is carried out on the basis of the previously performed SDR. At this stage, you need to specify the structure of each work, i.e. set the following parameters:

- identifier - a unique code that uniquely identifies the work in the project;

- Description – a brief description used in the network diagram of the project. Usually describes the essence of the work;

- Initial duration (duration). Estimate the time required to complete the work, taking into account its nature and the resources required. The estimation of the duration of work is influenced by time constraints, assumptions of the need for labor resources, their qualifications and experience in the implementation of previous projects;

- percentage of completion - the share of the completed part of the work as a percentage;

- the remaining duration for the work performed;

- calendar – a list of working and non-working periods, adopted for the performance of work in the project;

- early start and end, late start and end;

- Time reserves – free and complete. The free reserve determines the time for which it is possible to delay the performance of work without changing the early start of all subsequent work. A full reserve determines the time by which work can be delayed without changing the duration or timing of the completion of the entire project. Defined as the difference between late and early end of work;

- actual beginning and ending;

- previous work - work on which the timing of the performance of this work, which is technologically or logically preceding it, depends;

- subsequent work - work, the timing of which depends on the performance of this work, technologically and logically following this one.

2. Determining the sequence of work The sequence of work is determined by building a network model of the project.

A network model is a graphical representation of the works and milestones of the project and their interrelations. The network model is not a flowchart, it models only the logical dependencies between elementary works.

There are 4 types of logical connection between works:

1) "End – Beginning". 

Successor work can only begin after the predecessor work is finished.

2) "Beginning – Beginning". 

The successor work can only begin after the predecessor work begins. For example, technical editing may not start before normal editing is complete, but in order to start technical editing, it is not necessary to wait for the end of regular editing. With the help of such a connection, tasks that must be performed almost simultaneously are combined.

3) "End – End". 

The successor work can be completed only after the predecessor work is completed. This relationship combines tasks that must be performed almost simultaneously, but one cannot end until the other is completed. For example, the delivery-acceptance of the program goes simultaneously with the correction of errors found in the process of delivery-acceptance, until the correction of errors is completed, the delivery-acceptance will not end.

4) "Beginning – End". 

The successor work can only be completed after the predecessor work begins. Typically, this relationship is used when work A is a fixed-start date task that cannot be changed. In this case, the start date of the subsequent task does not change as the duration of the previous task increases. For example, such a connection is used when it is necessary to plan the supply of expensive equipment and preparatory work should be carried out during all available time before delivery.

To set the time intervals between works, it is possible to use a time lag - the delay between the follower and the predecessor. The time lag can have both a positive value (delay) and a negative one (advance).

In addition to the considered logical connections between the works in practice, there are other situations. For example, there are works that cannot be logically linked to any of the project's works. There are also works that have time constraints and should be scheduled for some specific timeframe, which have a connection with the calendar date, and not with the logical predecessors or followers of these works in the project. In this case, you need to specify the type of constraint. Depending on the type of restriction you choose, the work will be scheduled in time accordingly:


The use of works of different types allows you to build the most optimal model of the project.

Choosing a work constraint type resolves the issue of work scheduling and helps the user to optimally model the project from time parameters that do not depend on the number of resources assigned to the work. The type of constraint affects the point in time at which the schedule will be scheduled, regardless of its duration. However, the duration of the work itself may depend on the number of resources assigned to the task.

But that's not always the case. Sometimes the duration of work does not depend on the number of resources and has a strictly defined duration, for example, according to the technological cycle. You can take these features into account using the type of work.

Consider the types of work.

Any work can be evaluated by three parameters:

· duration;

· the number of resources required (the number of people assigned to work);

· amount of work (labor)

according to the formula:

Work = Duration x Resources

Depending on these parameters, three types of work can be distinguished:

· work with fixed labor costs,

· work with a fixed duration,

· work with a fixed amount of resources.

When you change the type of work, one of the parameters in the formula is fixed and it is determined which parameter of the work will be calculated:

Fixed work is work in which any changes to the duration or number of assigned resources do not affect the amount of work.


Work = Duration x Resources


(A certain amount of work is set, for example, 1 person can dig a 2x2 hole with a depth of 1 m in 2 days, and maybe 2 people in 1 day).

Fixed-duration work is a job in which any changes in the scope of work or the number of resources assigned do not affect the amount of work duration.

Duration = Work / Resource Units

(For example, the technological cycle of manufacturing a part is 1 hour. 1 person works, 8 parts are made per shift on 1 machine. If you put 2 people, they will make 16 parts per shift, but the cycle of its manufacture will not change).

Sometimes when assigning 2 people to work, instead of one, they either load halfway or do the work 2 times faster. To take this into account, the resource effort factor will help. If you use fixed-duration work, you can't get the job done faster.

To take into account the coefficient of resource efforts when performing work, it is necessary to fix the amount of work. In this case, you can reduce the resource unit utilization in proportion to the increase in the number of resources that are assigned.

Fixed resource work is a job in which any changes in the scope of work or duration do not affect the amount of resources that are assigned.

Resource Units = Work / Duration

If you also fix the amount of work, you can automatically change the duration of work with a fixed amount of resources in proportion to the number of resources assigned to it. resource loads will not be recalculated

3. Estimating the duration of work. Estimate the duration of work can be done in 4 ways:

  • · according to the standards;
  • · by scope of work;
  • · by analogues;
  • · with the involvement of experts.

4. Development of a calendar plan. 

For the effective use of time, it is necessary to master not only personal skills, but also existing techniques, of which among the most accessible and basic are network models that show the logical relationship of work.

The network model is widely used in the development of the calendar schedule.

The development of a calendar plan is the most important stage in project planning. The success of the entire project depends to a greater extent on the effectiveness of project deadline management. If the project is completed with a delay in time, then with a high degree of probability the project budget will be exceeded and the quality of the final product or service will be reduced. It would be good to be able to say that "With the resources available, the project will take such and such a time", however, the reality is that most projects have well-defined start and end dates. For example, you'd like to start immediately, but people or materials won't be ready for another two weeks. Be that as it may, stakeholders expect or need the project to be completed by a certain time. Scheduling is a classic problem for all projects. A problem that every project manager should be able to solve.

There are two most common methods of project planning:

  • · Critical Path Method (CPM)
  • · method of evaluation and revision of plans (PERT).

Both methods reflect what needs to be done, how long each particular activity will last, in what order the work will be done, and who is designated as responsible for them.

When developing a schedule, the manager sometimes needs to highlight the main (key) events of the project, for example, the signing of the contract, commissioning, the completion of the stage. These works are called milestones. Usually a milestone has zero duration, and with the right choice of milestones, they turn into a series of natural checkpoints.

1) Control of the calendar plan by the critical path method

Control of the timing of the project work can be carried out using the critical path method. An important prerequisite for applying the CPM method is the assumption that the execution time of each work is precisely known. As a result of using the CPM method, you can get answers to the following questions:

  • - In what minimum time can the project be completed?
  • - At what time should the individual works begin and end?
  • - What work is "critical" and must be completed exactly on time so as not to disrupt the project deadline?
  • - How long can the deadline for "uncritical" work be postponed so that it does not affect the project deadline?

2) Control of the calendar plan by the PERT method

The PERT method is focused on the analysis of such projects for which the duration of all or some of the work cannot be determined precisely. First of all, we are talking about the design and implementation of new systems. In such projects, many works have no analogues. As a result, there is uncertainty in the timing of the project as a whole.

Using the PERT method provides answers to the following questions:

  • - What is the expected time to complete the work equal?
  • - What equals the expected project execution time?
  • - With what probability can the project be completed in the specified time?

In order to use the PERT method, the following three estimates must be defined for each work i whose execution time is a random variable:

Optimistic time ai is the time to complete work i in the most favorable conditions.

The most likely time mi is the time it takes to perform work i under normal conditions.

Pessimistic time bi is the time of work i in adverse conditions.

Given that the turnaround time is well described by the beta distribution, the average or expected time ti of work to be completed i can be determined by the formula

ti = (ai + 4 mi + bi)/6.

If the work time i is known exactly and is equal to di, then

ti = ai = mi = bi= di.

With the above three estimates of lead times, we can also calculate the generally accepted statistical measure of uncertainty – variance 2i or variation vari of work time i:

s2i = vari = ((bi - ai )/6 ) 2.

If the work time i is known exactly, then s2i = vari = 0.

Let T be the time it takes to complete the project. If the project has work with an indefinite execution time, then the time T is a random variable. The expected expected value of the project execution time E(T) is equal to the sum of the expected values of the work time lying on the critical path. The CPM method can be used to determine the critical path of the project. 


At this point in the project analysis, the execution time of the work is assumed to be equal to the expected time ti. The variation (variance) of the total time required to complete the project, assuming the independence of the times of work, is equal to the sum of the variations of the works of the critical path. If two or more works are interdependent, then the specified amount gives an approximate idea of the variation in the time of completion of the project.

3. Optimization and control of the calendar plan.

 In order for the developed schedule to be used in reality, it is necessary to optimize it in order to introduce into the schedule the existing restrictions on the timing of work, available resources and the budget laid. In other words, you need to optimize your schedule. Optimization is a multi-criteria and iterative procedure. Based on these optimality criteria, three optimization steps are performed:

  • · temporary;
  • · resource;
  • · cost.

The purpose of the temporary optimization of the schedule is to bring the project terms in line with the required (contractual, contractual or other). To reduce the duration of work, you must use one of the following methods:

  • · re-evaluation of the duration of work;
  • · additional detailing of the work;
  • · change the number of resources assigned to work (for specific types of work).

Resource optimization can be carried out for the following reasons:

  • · the time frame for which the work is planned does not coincide with the time frame within which the resources are allocated;
  • · the number of resources required exceeds the number of available resources.
  • · the amount of work planned for a certain period of time cannot be completed by the available number of resources. This situation is called a resource conflict, and the procedure for resolving it is called resource leveling. This is the main element of the resource optimization process.

In the process of resource alignment, the manager can do the following operations:

  • · increase the number of available resources,
  • · change the degree of resource load and their number on the works.

Modify the project schedule so that the number of available resources described ensures that the planned amount of work is completed within the planned time frame. This procedure is carried out by postponing the timing of the work, taking into account the technology of their implementation.

Cost optimization of the calendar project plan pursues the following goals:

  • · reduction of the cost of individual works of the project;
  • · optimization of the cost of the entire project;
  • · alignment of the volume and cost of work planned for a certain period of time and financial costs planned for the same period.

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