Lecture 8 CLUSTERS AS A FORM OF INTER-ORGANIZATIONAL NETWORK INTERACTION key competencies firms and other organizations

Lecture 9 INFORMATION AND COMMUNICATION TECHNOLOGIES IN THE DEVELOPMENT OF NETWORK INTERACTION OF COMPANIES

Lecture 10 PROSPECTS FOR THE DEVELOPMENT OF NETWORK INTERACTION OF COMPANIES IN THE RUSSIAN MARKET

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Calendar plan (schedule) of work production is, of course, a key document of the PPR. The success of the project implementation largely depends on the quality of its development. The calendar plan is a model construction industry, which establishes a rational sequence, priority and timing of work at the facility.

scheduling

Essence scheduling, its role in the construction

Calendar planning is an integral element of the organization of construction production at all its stages and levels. The normal course of construction is possible only when it is thought out in advance in what sequence the work will be carried out, how many workers, machines, mechanisms and other resources will be required for each work. Underestimation of this entails inconsistency in the actions of performers, interruptions in their work, delays in terms and, of course, an increase in the cost of construction. To prevent such situations, a calendar plan, which performs the function of a work schedule within the accepted duration of construction. Obviously, the changing situation at the construction site may require a significant adjustment of such a plan, however, in any situation, the construction manager must clearly understand what needs to be done in the coming days, weeks, months.

The duration of construction is assigned, as a rule, according to the norms (SNiP 1.04.03-85 * Standards for the duration of construction ...) depending on the size and complexity of the facilities under construction, for example, the area of ​​hydro-reclamation systems, types and capacities of industrial enterprises, etc. In some cases, the duration of construction may be planned different from the normative (most often in the direction of tightening the deadlines), if required by the needs of production, special conditions, conservation programs, etc. For facilities built in complex natural conditions, an increase in the duration of construction is acceptable, but this must always be properly justified.

In construction practice, simplified planning methods are often used, when, for example, only a list of works is compiled with the deadlines for their implementation without proper optimization. However, such planning is permissible only when solving small current tasks during construction. When planning large objects of work for the entire period of construction, careful work is needed to select the most appropriate sequence of construction and installation works, their duration, the number of participants, it is necessary to take into account many factors mentioned above. For these reasons, various forms of scheduling are used in construction, allowing in their own way to optimize the planned course of work, the possibility of maneuvers, etc.

• line calendar charts
• network charts

In addition, depending on the breadth of the tasks to be solved, the required degree of detail of solutions, there are different kinds calendar plans that are used on different levels planning.

When developing schedules in PIC and PPR, the best results are achieved when several options for the schedule are compiled, and the most effective one is selected.

Types of calendar plans (schedules)

There are four types of calendar schedules, depending on the breadth of the tasks to be solved and the type of documentation they are included in. All types of calendar schedules should be closely linked to each other.

Consolidated calendar plan (schedule) in the POS determines the order of construction of objects, i.e. the start and end dates of each object, the duration of the preparatory period and the entire construction as a whole. For the preparatory period, as a rule, a separate calendar schedule is drawn up. The existing norms (SNiP 12-01-2004 instead of SNiP 3.01.01-85) provide for the preparation of calendar plans in the PIC in monetary form, i.e. in thousand rubles with distribution by quarters or years (for the preparatory period - by months).

For complex facilities, especially water management and hydraulic engineering, additional summary graphs are compiled, oriented to physical volumes.

When drawing up calendar plans for the construction of hydraulic and water facilities, it is required, as already noted, careful coordination of the progress construction works with the timing of skipping water flow in the river, the timing of blocking the channel and filling the reservoir. All these terms should be clearly reflected in the calendar plan. During the reconstruction of such facilities, minimum breaks in the operation of a hydroelectric complex or hydraulic structure.

At the stage of developing a consolidated calendar plan, the issues of dividing construction into stages, start-up complexes, technological units. The calendar plan is signed by the chief engineer of the project and the customer (as a coordinating authority).

Object Schedule in the PPR determines the sequence and timing of each type of work at a particular facility from the beginning of its construction to commissioning. Typically, such a plan is broken down by months or days, depending on the size and complexity of the object. The object calendar plan (schedule) is developed by the compiler of the PPR, i.e. by the general contractor or a specialized design organization engaged for this purpose.

When developing calendar plans for reconstruction or technical re-equipment industrial enterprise it is necessary to coordinate all terms with this enterprise.

Working calendar schedules usually compiled by the production and technical department construction organization, less often by line personnel during the construction and installation works. Such schedules are developed not for a week, a month, several months. Weekly charts are most widely used. Working calendar schedules are an element operational planning which must be maintained continuously throughout the construction period.

The purpose of the work schedules, on the one hand, is to detail the object calendar plan and, on the other hand, to respond in a timely manner to all kinds of changes in the situation at the construction site. Work schedules are the most common type of scheduling. As a rule, they are compiled very quickly and often have a simplified form, i.e., as practice shows, they are not always properly optimized. Nevertheless, they usually take into account the actual situation at the construction site better than others, since they are compiled by persons directly involved in this construction. This is especially true for accounting weather conditions, features of interaction between subcontractors, implementation of various rationalization proposals, i.e. factors that are difficult to predict in advance.

Hourly (minute) charts in technological maps and maps labor processes compiled by the developers of these maps. Such schedules are usually carefully thought out, optimized, but they are focused only on typical (most likely) operating conditions. In specific situations, they may require significant adjustments.

Simplified scheduling forms

At short term planning, as already noted, in construction practice a simplified form of scheduling is often used in the form of a list of works with deadlines for their implementation. This form is not visual and is not suitable for optimization, but when solving current problems for the coming days or weeks, it is acceptable due to the simplicity and speed of its compilation. Usually this is the result of an agreement on the timing of work between the performers, which is recorded in the form of a protocol of a technical meeting, an order from the general contractor, or another current document.

The simplified form should also include construction planning in cash. In this case, some optimization is possible, but it solves such issues only in an extremely generalized form, since it relates primarily to construction financing. A calendar plan in terms of money is usually drawn up for especially large amounts of work, when a whole object or complex of objects acts as an element of planning. Such plans are typical, for example, for PIC.

Line calendar charts

A linear calendar chart (Ganga chart) is a table of "work (objects) - time", in which the duration of work is depicted as horizontal line segments.

Such a schedule provides opportunities for optimizing construction and installation works according to a wide variety of criteria, including the uniformity of the use of labor, mechanisms, building materials etc. The advantage of line charts is also their clarity and simplicity. The development of such a schedule includes the following steps:

• drawing up a list of works for which a schedule is being made
• determining their production methods and volumes
• determination of the labor intensity of each type of work by calculations based on existing time standards, aggregated standards or local experience data
• drawing up the initial version of the schedule, i.e. preliminary determination of the duration and calendar deadlines for the implementation of each work with the display of these terms on the chart
• schedule optimization, i.e. ensuring a uniform need for resources, primarily in the labor force, ensuring the timely completion of construction, etc., establishing the final calendar dates for work and the number of performers.

The results of each stage of development, the calendar plan, must be carefully verified, because errors, as a rule, are not compensated for at subsequent stages. For example, if at the first stage the volume of any work is estimated incorrectly, its duration and deadlines will be incorrect, and the optimization will be imaginary.

When determining the complexity of work, it is necessary to pay attention to Special attention the reality of the calculations, taking into account specific working conditions. The latter may differ significantly from those accepted in the norms, so the compiler of the calendar plan must be well acquainted with the actual conditions of construction.

The main disadvantage of linear graphs is the difficulty of their adjustment in case of violations of the initial terms of work or changes in the conditions for their implementation. These shortcomings are eliminated with another form of scheduling - network charts.

network charts

The network graph is based on the use of another mathematical model - a graph. Graphs (obsolete synonyms: network, maze, map, etc.) are called by mathematicians "a set of vertices and a set of ordered or unordered pairs of vertices." Speaking in a more familiar (but less precise) language for an engineer, a graph is a set of circles (rectangles, triangles, etc.) connected by directed or non-directed segments. In this case, the circles themselves (or other figures used) according to the terminology of graph theory will be called "vertices", and the non-directional segments connecting them - "edges", directed (arrows) - "arcs". If all the segments are directed, the graph is called directed; if all segments are undirected, the graph is called undirected.

The most common type of work network diagram is a system of circles and directed segments (arrows) connecting them, where the arrows represent the work itself, and the circles at their ends ("events") - the beginning or end of these works.

The figure shows in a simplified way only one of the possible configurations of the network diagram, without data characterizing the planned works themselves. In fact, the network diagram provides a lot of information about the work being done. Above each arrow is written the name of the work, under the arrow - the duration of this work (usually in days).

The circles themselves (divided into sectors) also contain information, the meaning of which will be explained later. A fragment of a possible network diagram with such data is shown in the figure below.

Dotted arrows can be used in the graphics - these are the so-called "dependencies" (dummy jobs) that require neither time nor resources.

They indicate that the "event" to which the dotted arrow points can only occur after the event from which the arrow originates.

There should be no dead ends in the network diagram, each event should be connected by a solid or dashed arrow (or arrows) with any previous (one or more) and subsequent (one or more) events.

Events are numbered approximately in the order in which they will occur. The initial event is usually located on the left side of the graph, the final event - on the right.

A sequence of arrows in which the beginning of each subsequent arrow coincides with the end of the previous one is called a path. The path is indicated as a sequence of event numbers.

In a network diagram, there can be multiple paths between start and end events. The path with the longest duration is called the critical path. The critical path determines the total duration of activities. All other paths have a shorter duration, and therefore the work performed in them has time reserves.

The critical path is indicated on the network diagram by thickened or double lines (arrows).

Two concepts are of particular importance when drawing up a network diagram:

Early start of work - the period before which it is impossible to start this work without violating the accepted technological sequence. It is determined by the longest path from the initiating event to the start of this work.

Late finish is the latest end date for a job that does not increase the total duration of the job. It is determined by the shortest path from a given event to the completion of all work.

When evaluating time reserves, it is convenient to use two more auxiliary concepts:

Early finish is the deadline before which the work cannot be completed. It is equal to the early start plus the duration of this work.

Late start - the period after which it is impossible to start this work without increasing the total duration of construction. It is equal to the late finish minus the duration of the given work.

If the event is the end of only one job (that is, only one arrow is directed to it), then the early end of this job coincides with the early start of the next one.

The total (full) reserve is the maximum time for which the execution of this work can be delayed without increasing the total duration of the work. It is determined by the difference between late and early start (or late and early finish - which is the same).

Private (free) reserve - this is the maximum time for which you can delay the execution of this work, without changing the early start of the next one. This fallback is only possible when the event includes two or more activities (dependencies), i.e. two or more arrows (solid or dotted) point to it. Then only one of these jobs will have an early finish that coincides with an early start of the subsequent job, while for the others these will be different values. This difference for each work will be its private reserve.

In addition to the described type of network graphs, in which graph vertices ("circles") represent events, and arrows represent jobs, there is another type in which the vertices are jobs. The difference between these types is not fundamental - all the basic concepts (early start, late finish, general and private reserves, critical path, etc.) remain unchanged, only the ways of writing them differ.

The construction of a network diagram of this type is based on the fact that the early start of the subsequent work is equal to the early end of the previous one. If this job is preceded by several jobs, its early download should be equal to the maximum early completion of previous jobs. The calculation of late dates is carried out in the reverse order - from the final to the initial one, as in the "nodes - events" network diagram. For a finishing activity, late and early finish are the same and reflect the length of the critical path. The late start of the next activity is equal to the late finish of the previous one. If a given work is followed by several works, then the minimum value from the late beginnings is decisive.

Network "nodes - work" graphs appeared later than "nodes - events" graphs, therefore they are somewhat less known and relatively less often described in educational and reference literature. However, they have their advantages, in particular they are easier to build and easier to adjust. When adjusting "completed - work" graphs, their configuration does not change, but for "nodes - events" graphs, such changes cannot be excluded. However, at present, the compilation and correction of network graphs are automated, and for a user who only their time reserves, it does not really matter how the schedule is made, i.e. what type it is In modern specialized planning and computer software packages operational management the type "tops - works" is generally used.

Network diagrams are corrected both at the stage of their compilation and use. It consists in optimizing construction work in terms of time and resources (in particular, the movement of labor). If, for example, the network schedule does not ensure the completion of work within the required time frame (normative or established by the contract), it is adjusted in time, i.e. shortening the critical path. This is usually done

due to the time reserves of non-critical work and the corresponding redistribution of resources

by attracting additional resources

by changing the organizational and technological sequence and the relationship of work.

In the latter case, the graphs "vertices - events" have to change their configuration (topology).

Adjustment for resources is made by constructing linear calendar graphs for early beginnings, corresponding to one or another variant of the network diagram, and adjusting this variant.

Automated construction management systems usually include computer programs that, to one degree or another, automate almost all stages of compiling and adjusting network schedules.

Reference literature

• SNiP 1.04.03-85 "Standards for the duration of construction and groundwork in the construction of enterprises of buildings and structures";
• MDS 12-81.2007 " Guidelines for the development and execution of a project for the organization of construction and a project for the production of works.

Often, during the development of various kinds of projects, a task execution plan is drawn up. Tools Microsoft Excel allows you to create a network diagram, which serves to solve the problem of planning project stages.

Let's make a simple chart using a Gantt chart.
First you need to create the table itself with columns with appropriate headings.

After that, you can see a new window in which we select the "Alignment" tab. Alignment in the fields, specify "Centered", and in the display settings, check the box next to "Wrap by words".

Go to the working window and set the borders of the table. We select the headings and the required number of cells for the table, open the "Home" section, and in it, using the corresponding icon in the list, select the "All Borders" item.

As a result, you can see that the table frame with headers has been created.

The next step is to create a timeline. This is the basic part in a network diagram. A certain set of columns corresponds to a particular period in the planning of project tasks. AT this example will create a 30 day timeline.

For now, we leave the main table and select thirty columns near its right border in the context of this example. It is worth noting that the number of rows = the number of rows in the previously created table.

Go to the "Home" section and select "All borders" in the borders icon as well as with the table created earlier.

In this example, we define the plan for June 1-30. And we enter the corresponding dates in the timeline. For this, the "Progression" tool will be used.

After clicking on the "Progression" item, a new window will appear. In it, we mark the location by line (in this example), and select dates as the type. Depending on what time interval is used, select the "Day" item. Step value - 1. Set the date June 30 as the final value and confirm the action.

Next, the timeline will be filled with days from 1st to 30th. Next, you need to optimize the table for its convenience by selecting the entire time period and pressing the right mouse button. Select "Format Cells" from the context menu.

A new window will appear in which you need to open the "Alignment" tab and set the value to 90 degrees. We confirm the action.

But the optimization is not complete. Go to the main section "Home" and click on the "Format" icon and select autofit by line height in it.

And to complete the optimization, we do a similar action and select autofit according to the column width.

As a result, the table has acquired a complete form.

The final step will be to fill the first table with the relevant data. Also, if there is a large amount of data, then by holding down the "Ctrl" key on the keyboard, drag the cursor along the border of the numbering field down the table.

And as a result - the table is ordered. And you can also fill in the rest of the fields of the table.

In the "Home" section, you need to click on the "Styles" icon and in it click on the "Conditional Formatting" icon. And in the list that appears, select the item "Create a rule".

After this action, a new window will open in which you need to select a rule from the list of rules. Select "Use formula to determine formatted cells". The appropriate selection rule specifically for our example is shown in the box.

Let's analyze the elements of the formula:

G$1>=$D2 is the first argument, which specifies that the value in the timeline be equal to or greater than a certain date. The first part of the element points to the first cell, and the second part to the desired part of the column regarding the plan.
G$1I - check values ​​for truth
$ - allows you to set the values ​​as absolute.

To set the color of the cells, click "Format".

Optimization of the company's work, especially manufacturing enterprise, is one of the most important conditions for the existence of the company. Not only competition requires an uninterrupted flow production process. Modern tendencies minimizing the cost of manufactured products primarily involves the elimination of downtime and the consistency of operations.

To solve these problems, a technique for optimizing activities and calculating the timing of work is used. The developed network schedule allows you to determine the logical sequence of individual operations, the possibility of combining them in time, as well as the deadlines for completing everything. production cycle works.

What's this?

One of the methods for effective planning of the activities of a manufacturing enterprise is the construction of a network diagram. Initially, it was used in construction and determined not so much the sequence of work as the timing of reaching construction site teams of workers of different specialties. It's called the "work schedule".

AT modern conditions, when large enterprises mass-produce products, to facilitate and increase productivity, the whole process is divided into simple operations. Therefore, the network schedule "migrated" from construction to almost all industries.

So what is displayed in this document? First, all the operations necessary for the release of goods (production of services) are listed in detail. Secondly, the logical interdependence between them is determined. And, finally, thirdly, not only the timing of each specific work is calculated, but also the time required to complete the production process.

By exposing the internal dependencies of project activities, the network schedule becomes the basis for scheduling equipment and workforce utilization.

The concept of "operation" in network planning

In the network schedule, you can evaluate the periods of start (end) of work, forced downtime and, accordingly, the maximum delay in the production of certain operations. In addition, critical operations are identified - those that cannot be performed with a deviation from the schedule.

Understanding the terminology of planning, it is necessary to clearly understand what an operation is. Most often, this is understood as an indivisible part of the work that requires time to complete. Further, we understand that the operation is associated with costs: time and resources (both labor and material).

In some cases, no resources are needed to perform some actions, only time is required, which takes into account the network schedule. An example of this is the expectation of concrete hardening (in construction), the cooling time of rolled parts (metallurgy), or simply the approval (signing) of a contract or permits.

Most often, operations in planning are given a name in the imperative mood (develop a specification); sometimes verbal nouns are used for names (specification development).

Operation types

When compiling a network schedule, there are several types of work:

• merge - this operation is immediately preceded by more than one work;
• parallel operations are performed independently of each other and, at the request of the design engineer, can be performed simultaneously;
• a crushing operation implies that after its execution, several unrelated jobs can be performed at once.

In addition, there are a few more concepts necessary for planning. The path is the time to complete and the sequence of interdependent operations. A critical path is the longest path of the entire system of work. In the event that some operation on this path is not performed on time, the deadlines for the implementation of the entire project are disrupted.

And the last: event. This term usually refers to the beginning or end of some operation. The event does not require resources.

What does the chart look like

Any graph familiar to us is represented by a curve located on a plane (less often in space). But the type of network plan is significantly different.

The network diagram of the project may look two ways: one technique involves the designation of operations in the nodes of the block diagram (OS), the second uses connecting arrows (OS) for this. It is much more convenient to use the first method.

The operation is indicated by a round or rectangular block. The arrows connecting them define the relationships between the actions. Since the titles of works can be quite long and voluminous, the numbers of operations are put down in the blocks, and a specification is drawn up for the schedule.

Schedule Design Rules

For proper planning, you need to remember a few rules:

1. The graph unfolds from left to right.
2. Arrows indicate links between operations; they may intersect.
3. Each simple work must have its own serial number; any subsequent operation cannot have a number less than that of the previous one.
4. The graph cannot have loops. That is, any looping of the production process is unacceptable and indicates an error.
5. You cannot use conditions when a network graph is built (an example of a conditional order: “if an operation is performed .., perform work ... if not, do not take any action”).
6. To indicate the beginning and end of work, it is more convenient to use one block that defines the initial (final) operations.

Construction and analysis of the graph

For each job, three things need to be clarified:

1. A list of operations that must be completed prior to this job. They are called preceding in relation to the given one.
2. A list of operations that are performed after a given action. Such works are called the following.
3. The list of tasks that can be carried out simultaneously with the given one. These are parallel operations.

All the information received gives analysts the necessary basis for building logical relationships between the operations included in the network diagram. An example of building these relationships is shown below.

The real schedule requires a serious and objective assessment of the production time. Determining the time and entering it into the schedule makes it possible not only to calculate the duration of the entire project, but also to identify the most important nodes.

Graph Calculation: Direct Analysis

Estimation of time costs for the performance of one operation is made on the basis of standard labor costs. Thanks to the direct or inverse calculation method, you can quickly navigate the order of work and identify critical steps.

Direct analysis allows you to determine the early start dates for all operations. Reverse - gives an idea of ​​late dates. In addition, using both analysis techniques, you can not only establish the critical path, but also identify time intervals by which you can delay the execution individual works without disrupting the overall timing of the project.

Direct analysis looks at the project from start to finish (if we talk about the drawn up schedule, then the movement along it occurs from left to right). During the movement along all chains of operations, the time for completing the entire complex of works increases. Direct calculation of the network diagram assumes that each subsequent operation begins at the moment when all previous ones end. At the same time, it must be remembered that the next job starts at the moment when the longest of the immediately preceding ones ends. At each step of direct analysis, the execution time of the settlement operation is added. This gives us the values ​​of early start (ES) and early finish (EF).

But you need to be careful: the early end of the previous operation becomes the early start of the next one only if it is not a merge. In this case, the start will be the early end of the longest of the previous works.

reverse analysis

The reverse analysis takes into account such parameters of the network schedule: late completion and late start of work. The name itself suggests that the calculation is carried out from the last operation of the entire project towards the first (from right to left). Moving towards the start of work, you should subtract the duration of each activity. Thus, the most late dates start (LS) and end (LF) of work. If the time frame of the project is not initially set, then the calculation starts from the late end of the last operation.

Calculation of temporary reserves

Having calculated the network schedule of work in both directions, it is easy to determine temporary downtime (sometimes the term “fluctuation” is used). The total possible delay time for the execution of an operation is equal to the difference between the early and late start of a particular action (LS - ES). This is the time reserve that will not derail the overall time frame for the project.

After calculating all the fluctuations, they begin to determine the critical path. It will go through all operations for which there is no timeout (LF = EF; and respectively LF - EF = 0 or LS - ES = 0).

Of course, in theory, everything looks simple and uncomplicated. The developed network schedule (an example of its construction is shown in the figure) is transferred to production and implemented. But what is behind the numbers and calculations? How to use possible technological downtime or, conversely, avoid force majeure situations.

Management experts suggest assigning the most experienced employees to perform critical operations. In addition, when assessing the risks of a project, it is necessary to pay special attention not only to these steps, but also to those that directly affect the critical path. If it is not possible to control the progress of work as a whole, then it is necessary to find time to obtain primary information from the operations of the critical path. It is about talking directly with the performers of such works.

Network diagram - a tool for optimizing the company's activities

When it comes to the use of resources (including labor), it is much easier for a manager to manage them if there is a network schedule for the production of work. It shows all the downtime and employment of each individual employee (team). The use of an unemployed worker at one facility to implement another allows you to optimize the company's activities as a whole.

Don't overlook another practical advice. In reality, project managers are faced with the "desires of senior management" to see the work done "yesterday". In order to avoid panic and the release of marriage, it is necessary to strengthen resources not so much on the operations of the critical path, but on those that directly affect it. Why? Yes, because there is no downtime on the critical path, and it is often impossible to reduce the time of work.

Section VI.

NETWORK MODELING OF CONSTRUCTION PRODUCTION

147. What are the disadvantages of line charts?
Line graphs are easy to implement and clearly show the progress of construction work. However, they cannot reflect the complexity of the simulated construction process and therefore have the following disadvantages:
- the calendar schedule is static: it does not reflect the entire dynamics of the construction process and needs to be constantly adjusted. But while it is being adjusted, agreed upon and approved, new changes occur, as a result of which the revised schedule again does not reflect the actual state of affairs;
- it is difficult to determine how construction is going on in a linear schedule this moment- ahead or behind, and for how long;
- according to the linear schedule, it is difficult to determine how the non-fulfillment of one or several works affects the performance of other works, and for how long;
- on the calendar chart works that determine the construction time are not allocated; the role of secondary works is not visible, as a result of which the construction management is forced to disperse its attention to all works, not concentrating it on the decisive sections of the construction site;
– a line graph does not make it possible to predict the course of events at a construction site, which complicates the choice right decision construction manager for subsequent work.

148. What is a network diagram?
A network diagram is a graphic representation of the technological sequence of work at an object or several objects, indicating their duration and all time parameters, as well as the total construction period.
Construction management should be based on a pre-developed model of the construction and installation process, starting from preparatory work and ending with the commissioning of the facility.

149. What are distinctive features network graph in comparison with linear and cyclogram?
The main features of a network diagram are:
- the presence of a relationship between the work and the technological sequence of their implementation;
- the possibility of identifying works, the completion of which primarily determines the duration of the construction of the facility;
- the ability to select options for the sequence and duration of work in order to improve the network schedule;
- facilitating the control of work over the progress of construction;
- the possibility of using a computer to calculate the parameters of the schedule in planning and managing construction.

150. What elements does the network diagram consist of?
A network diagram consists of four elements: activities, events, expectations, and dependencies.

151. What does the term "work" mean?
Work is technological process, requiring time, labor and material resources and leading to the achievement of a certain planned result. Work on the graph is indicated by a solid arrow, the length of which may not be related to the duration of the work (if the graph is not made on a time scale).

152. What does the term "event" mean?
The fact of completion of one or more works, necessary and sufficient for the beginning of subsequent works, is called an event. This means that the event takes place instantly, so it does not require time, material or labor costs. The event is depicted as a circle, inside which a certain number is indicated - the event code.

153. What types of events can there be?
Events can be initial, final, initial and final.
The initiating event starts the construction of the facility and has no previous activities. This event begins the development of the network diagram.
The end event has no follow-on work and ends the work in the network.
Events limit the work under consideration and in relation to this work they can be initial and final.
The start event for the activity in question determines the start of the activity and is the end event for previous activities.
The end event determines the fact of the end of this work and is the initial for subsequent work.

154. What does the concept of "waiting" mean?
In construction, there may be a need for breaks between work performed. Such breaks can be technological and organizational.
Technological breaks may be associated with the need for curing concrete, hardening the screed for rolled roofing, drying plaster before painting, etc.
Organizational breaks may occur when teams are busy the right professions at another facility, waiting for the warm season to perform landscaping work, and so on.
Such technological breaks are called waiting. Waiting is a process that takes time and does not consume material and labor resources. The wait is depicted, like the work, with a solid arrow indicating the duration and the name of the wait.

155. What does the concept of “dependence” mean?
There may be technological dependencies between certain types of construction and installation works (for example, it is impossible to carry out finishing work, installation technological equipment in the absence of a roof, landscaping without laying underground utilities, etc.).
Dependency (sometimes also called fictitious work) reflects the technological or organizational relationship of work. Addiction requires neither time nor resources; it determines the technological sequence of events.
Dependence is depicted on the network diagram by a dotted arrow.
Dependence can be technological (shows the necessary sequence of work) and resource or organizational, associated with the transfer of teams or the transfer of construction vehicles from site to site.

156. What is the concept of "path" in a network diagram?
Each activity in the network schedule has its own duration, calculated on the basis of the amount of work to be performed. Having passed from the initial event to the final one, sequentially, along the chain of work and dependencies, we can calculate the total duration of work in each chain.
A path is a continuous sequence of activities in a network diagram. The length of the desired path in time is determined by the sum of the duration of the works that make up this path.
In a network diagram, there can be several paths between the initiating and ending event, which vary in duration.

157. What is the full path of a network diagram?
The path from the initial to the final network event is called complete. The section of the path from the initial event to this event is called the previous one, and the path from this event to any subsequent one is called the subsequent path.

158. What is a critical path in a network diagram?
The critical path of a network diagram is the complete path from the initial to the final event, which has the greatest length (duration) of all complete paths. Its time length determines the time for completion of all activities in the network.
There can be multiple critical paths in a network diagram.
Increasing the duration of activities on the critical path increases the total duration of activities; accordingly, the reduction of these works leads to a general reduction in the construction period of the facility.
The critical path on the network diagram is highlighted with a thick line or in some other way.

159. What is a critical zone in a network diagram?
A path whose length is slightly less than the critical path is called subcritical. By reducing the duration of activities on the critical path, the subcritical path can become critical.
The combination of critical and subcritical paths forms a critical zone in the network diagram. Identification of the critical zone in the network schedule allows you to identify the work that needs to be paid attention to if it is necessary to reduce the construction time, either when designing the network schedule, or when monitoring the progress of construction.

160. What is a job code?
In a network diagram, each job is between two events (the initial one, from which it exits, and the final one, into which it enters). Each event has its own number, so each work gets its own code, consisting of the numbers of its initial and final events.

161. What are the basic rules for building a network graph?
There are certain rules for constructing a network graph:
- for the convenience of building a network graph, the direction of the arrows should be taken from left to right, avoiding, if possible, crossing lines;
- each work must have its own code. In the case of performing parallel jobs that have a common beginning and end, additional events must be introduced, otherwise various works will receive a single name;

- in the network diagram there should not be "dead ends" (events from which no work comes out) and "tails" (events that do not include any work);

– numbering (coding) of events must correspond to the sequence of work in time, i.e. previous events are assigned lower numbers;
- the numbering of events should be done only after the complete construction of the network and the conviction that the network is technologically built correctly;
- the initial version of the network diagram is built without taking into account the duration of its constituent works, providing only a technological sequence (in this case, the length of the arrows does not matter).

162. What does the concept of "time reserve" mean?
Comparing the length of the critical path with the length of any non-critical path, we establish that it is possible to increase the length of non-critical works for a certain amount of time without increasing the overall construction time of the facility. These days constitute a reserve of time, which can be private or general.

163. What is a private time reserve?
The private reserve of work time is the amount of working time by which the duration of this work can be increased or its start can be postponed so that the early start of subsequent work does not change.

164. What is the general reserve of time?
Under the total (full) reserve time is understood the amount of working time by which the duration of this work can be increased, provided that the duration of the largest of the paths passing through this work does not exceed the length of the critical path.

165. What is the calendar ruler used for when developing a network diagram?
When developing a network diagram, it is a non-scale model, but it becomes necessary to present it in a familiar form on a time scale that is available for use at any level of management. To link the chart to calendar time, a calendar ruler is used. By linking network events to a calendar, you can clearly see when what work is being done and when it should be completed.
A large-scale chart is usually built according to the early dates of events.

166. How to determine the earliest possible date for the completion of an event?
An event that includes one work can be started when the event of the previous work has occurred and the work of the event in question has been completed.
If the event under consideration includes several activities, then it is possible to proceed to the subsequent activity only when the longest activity included in this event is completed. Having data on the duration of each work included in this event, it is possible to determine for this event the earliest possible date for its completion.
The earliest possible date for the completion of an event is equal to the early start of the previous event and the duration of the longest path preceding this event.

167. How to determine the latest of the admissible dates for the completion of an event?
If the work in question has one successor, then its late finish is equal to the late finish of the successor minus the duration of the work in question.
If the job under consideration has two or more subsequent jobs, then its late completion will be the minimum of the difference between the late finishes of subsequent jobs and their duration.

168. What is the purpose of developing a "card-determinant" network diagram?
The card-determinant of the network diagram is the source document for the calculation of the network diagram. With the help of the identification card, the duration of each work is assigned based on the accepted methods of work production, the composition of the team and shifts are assigned.

169. What data is needed to draw up a map-determinant of the network diagram?
The initial data for the development of a map-determinant of the network diagram (Fig. 4) are:
- the exact name and composition of each work;
- data on the teams available in the construction organization and their composition;
- information on the productivity of labor achieved by these brigades;
- data on the supply of building materials and structures, equipment;
- information about current normative documents(SNiP, ENiR, instructions and guidelines for the production of work);
- data on the mechanisms that construction and installation organizations have.

Rice. 4. Card-determinant of works and resources of the network diagram

170. How to determine the duration of work?
Having determined the complexity of the work, you can determine the duration of the work in two ways:
- having appointed the strength of the brigade, divide the labor intensity of the work by the number of workers in the brigade;
- having assigned the duration of the work in days, divide the labor intensity of the work by its duration; in this case, we will find out the required strength of the brigade.
But these provisions do not apply to the performance of mechanized work. In this case, it is necessary to determine the required number of machine shifts of work and, dividing by the number of mechanisms and their shifts, obtain the duration of work in days; in accordance with ENiR, we appoint the composition of the installation team.

171. How are network graphs stitched together?
For certain types construction and installation works, local schedules can be developed, which must be combined into a single network schedule for the construction of buildings and structures.
In connection with this, it is necessary to link related works (this is the so-called "stitching" of the schedule). This linking must be done with the help of boundary events, i.e. events that are common to different local schedules and occur as a result of the completion of the work included in these schedules.

172. How to construct diagrams of labor and material resources?
As a result of calculating the network parameters and the possibility of linking it to the calendar, it is possible to identify the need for labor and material resources at each moment of the construction of the facility. To do this, a resource demand diagram is built, the horizontal vector of which is tied to the calendar, and the vertical vector indicates the amount of resources consumed. The construction of the diagram is based on the constancy of the expenditure of resources during the performance of each work. Adding the needs of work vertically within a certain calendar period provides the necessary information.
In order to correctly link the network to the calendar, the start dates of a particular work must correspond to the early start of work, located in the left sector of events.
Works that have a slack should be highlighted on the network diagram (on the graph they may have a broken line in that part of the work where there is a partial slack), and only that part of the work where there are resources is projected onto the diagram (Fig. 5 and 6). ).

Fig.5. An example of calculating a network diagram directly on the diagram

Fig.6. Building a network graph on a time scale and a diagram of the movement of labor (the number above the arrow is the number of people employed in this work)

173. For what purpose is the network schedule adjusted?
The first stage of developing a network schedule ends with the calculation of its parameters, determining the duration of the critical path and its trajectory. However, the initial (rather, initial) version of the schedule rarely turns out to be immediately optimal. Most often, the network has to be adjusted, bringing it into line with the normative or directive deadline for the construction of the facility, with the resources available to the performers (labor, material, necessary mechanisms).
After receiving the first version of the network schedule with the definition of the critical path, the calculation of time parameters for each work and the definition of time reserves, the network schedule needs to be analyzed.
Under the adjustment (optimization) of the network schedule, we mean the introduction of possible changes into its original version in order to achieve beneficial results and bring the schedule parameters to the indicators for which the network is planned.
To make these amendments, it is necessary to find the most profitable and possible technological solutions, and sometimes design solutions associated with a reduction in the period of construction and installation work or with a change in the technological sequence of their execution.
Adjustment of the network schedule can be made according to the given construction time, according to labor and material resources and other necessary indicators.

174. How is the network schedule adjusted in time?
If the initial version of the network schedule has a critical path that does not exceed the established construction deadline, then such a schedule can be considered optimal and recommended for execution.
In cases where the critical path in the original version of the network schedule exceeds the established construction time, it is necessary to adjust the schedule in terms of the “time” indicator in order to reduce the critical path period.
You can shorten the critical path in the following ways:
- redistribute labor resources from non-critical work to critical work, as a result of which the duration of non-critical work may increase within the available time reserves, and critical work will be reduced;
- to attract additional labor and material resources to perform critical work;
- review the network topology (change the technological sequence of work); increase the number of captures; perform separate construction and installation operations, where technology and safety of work allow in parallel);
- change, if possible, design solutions in order to reduce the duration of construction (increase the factory readiness of structures, conveyor-block assembly of coating structures, use prefabricated structures instead of monolithic ones, etc.).