Reduction of construction time as a result of increasing the shift to three

Salnikov Konstantin Evgenevich PhD in Economics Docent, the department of Economic Expertise and Financial Monitoring, Institute of Cybersecurity and Digital Technologies of MIREA – Russian Technological University 141206, Russia, Moskovskaya Oblast' oblast', g. Pushkino, ul. Pisarevskaya, 13A, kv. 73 salkonevg@gmail.com Other publications by this author

Experts distinguish three types of construction duration: actual, calculated, normative.

The standard duration of construction is determined in accordance with SP 48.13330.2010 "Organization of construction". This document is the main one for rational planning and, very importantly, mandatory for use ^[1]. Construction is carried out within certain deadlines, determined by the enlarged network schedules of the construction process, on which planning is based. The estimated duration is determined on the basis of such factors: the requirements of investors, the specific features of a particular object and others that affect the process of its implementation.

The period separating the start and completion of construction is the actual duration of this process. Its calculation should be carried out taking into account a number of factors:

socio-economic factors that serve to assess the construction indicators that are needed in order for the final result (commissioning of the facility) to be achieved;

various indicators of the project: the method of organizing the construction process, design solutions, required capacity, etc.;

technical level of construction: "innovation" of the process as a whole, automation of individual processes.

According to the source ^[2], the reduction of construction time ensures the presence of the following effects:

on the part of the contractor (in the process of construction production);

on the part of the customer (if the object is put into operation ahead of time or on time).

It is possible to highlight the main points due to which the effect of the customer is achieved and, therefore, its value is determined:

the time separating the moment of investing and making a profit is shortened;

the turnover of invested resources is accelerating; the early start of commissioning of the facility ensures early receipt of revenue from it.

Construction costs are reduced by about 0.8%-0.9% if its duration is reduced by a year ^[3]. Accordingly, it becomes about 2.1-2.3% more expensive if the construction time increases.

Currently, the Ministry of Regional Development of the Russian Federation is developing new construction standards for orders that are funded from the state budget. The new regulations will apply to all construction projects financed in this way. So, the terms of construction of such social facilities as a school – 11 months, a kindergarten – 6 months, an underground passage – 4 months, etc. are already approximately known. Experts note that such improvements will lead to almost 10% budget savings ^{[4] [5]}.

Not only with the help of new standards, it is possible to achieve an objectively established construction period – in this context, the design solution plays an equally important role. Project management covers a wide range of tasks, which include the preparation of a calendar schedule (plan) of work, the distribution of responsibility (appointment of the director of the construction project, selection of the project team), control over the execution of the plan, as well as quality control of work.

In accordance with ^{[6] [7] [8]}, with proper timing management, the project becomes more controllable, risks are reduced, better and faster management decisions are made, and an assessment of the possibilities for the construction project to be completed ahead of schedule is provided. That is why the introduction of high-quality project timing management is a very urgent task, both for the construction industry and for many other industries.

Construction is inevitably accompanied by the emergence of problematic issues, which can be solved in two ways, proposed by the management of construction projects. After reviewing the literary sources ^{[9] [10] [11]}, you can conditionally divide them. The first group includes methods aimed at investigating individual methods by which deadlines are managed. Konovalova A.V. described them in detail in her publications ^[12]. Critical chain methods, according to this author, are being improved due to the fact that buffers of time and resources are being determined for the tasks assigned to the project.

The second group of methods is focused on managing deadlines for specific purposes. Musina D.R. ^[13], for example, wrote in her article about how the shift method of project implementation will affect the calendar period allotted for its construction. Based on her calculations, it can be stated that in some cases the project may be more costly due to the delay in its implementation than the infusion of additional funds. This happens, in particular, with a high level of inflation, when the cost of a construction project increases significantly due to an increase in the cost of resources, including labor and material. In most cases, the most significant share of material costs is the cost of operating the means of mechanization, taking into account the time of use and the cost of operating one machine hour. These indicators are contained in the relevant collections of the GESN 2001-01 ^[14]. The cash flow of projects that can be classified as long-term changes in accordance with certain patterns considered by S.V. Volodin ^[15]. Thus, this factor identified a number of factors that influence such programs in terms of their cost and timing.

Similarly with any other collective activity, labor needs organization, planning and management. So, resources and work must be coordinated in space and time.

The modern style of leadership in the construction industry is unthinkable without the on-line organization of work. This means that when developing a calendar plan, a competent manager assigns a key role in it to the formation of teams. At the time of the formation of the calendar planning, the selection of machines and mechanisms should be completed and the most complete and rhythmic loading of the operated key machines should be ensured thanks to a competently compiled schedule. The machines must have a full load of 2 or 3 shifts without downtime and transportation^[16].

The performance of machines and mechanisms should be the only criterion in determining the duration of their operation. This means that calculations should begin with determining the duration of mechanized work, on the parameters of which all further work on the schedule depends, determining the duration of manual work.

The main type of work during the development of the calendar plan is a technological process that is carried out on the private front by the forces of a permanent staff of performers (teams, links), whose unifying factor is a single final product. So rebar workers, carpenters and concrete workers, united in links, are engaged in the construction of monolithic foundations. In other words, the nomenclature of works means various works (installation, general construction, special), which are carried out by separate teams during the construction of the facility.

It requires the consolidation of technological operations in order to obtain such a nomenclature – from them comes the formation of TKR (technological complexes of works). Key conditions for their formation:

the ability to combine individual technological operations so that they are carried out on one private front;

the leading work, which is the work with the greatest labor intensity or carried out with the involvement of the leading mechanism. At the same time, other works in this case become accompanying. When the leading work is completed, its result is expressed by the finished type of structure structures or an intermediate stage of construction (for example, a pit), which is necessary from a technological point of view;

carrying out individual works in strict technological compatibility mode with the possibility of carrying them out by a team (complex or one specialized).

The compilation of the nomenclature of types of work is carried out in accordance with the technological sequence of their implementation.

The formula for calculating the duration of work without interruption at the ti facility looks like this:

t_i = (?Q_k)/(N_i?* n_i), (1)

where:

?Q _k – the total labor intensity of individual work, people-days.;

N _i – the number of people in the team performing the i-th type of work, people.;

n _i is the number of shifts per day when performing the i–th type of work.

The amount of work is proportional to the duration of the complex of works on private fronts. If there are the same volumes of work on private fronts, it is necessary to divide the total duration of the complex of works by the number of private fronts.

The specific conditions of the construction process affect the daily number of shifts (shifts) for all work complexes. Often, work in one shift is carried out when it comes to work:

for which increased caution is required (for example, carrying out glass works) or special working conditions;

during which mainly women work (plastering and painting works).

Two shifts are necessary for carrying out work involving mechanisms and machines, as well as construction and installation work.

Three shifts are recommended to be introduced in the case of:

continuous technological process (for example, with continuous concreting of large structural elements);

the use of mechanisms that are expensive and require a small number of workers for maintenance;

availability of unlimited work fronts (construction of tunnels and mines);

the need to reduce the total duration of the construction process, if all other possibilities are exhausted.

At the beginning of the formation of teams, the most optimal conditions of the construction process and methods of work are first selected.

The final construction products also affect the process of choosing the composition of the teams. When planning, they assume the immutability of the composition of the brigades during the change of fronts, that is, we are talking about a constant intensity of work.

A private front is a part of an object or a separate independent object, for which only one brigade can be involved. The brigade is an association of workers of various specialties. At the same time, the main task is to ensure that they can work together on the same private front.

Construction processes are of three types: non-mechanized (they are also called small mechanization), mechanized with an accompanying link of workers, mechanized.

When forming teams for a non-mechanized process, the main condition is that during the performance of a particular type of work they are involved evenly. This indicates the same rhythm of flows, that is, each type of work is performed approximately the same way. The same workload of all specialists is required. The increase in the quantitative composition of the brigade is a multiple relative to the normative composition of the link. This makes it possible for all specialists to be loaded equally. In the case when non-mechanized work is carried out, a link with a minimum work completion time is accepted.

It is required to determine the regulatory (directive) time of all types of work in order for this condition to be fulfilled:

t = (?q _slave)/(N _n), (2)

where:

q _slave – the labor intensity of the workers of the normative composition of the link;

n is the number of shifts per day;

N is the number of workers in the link.

The time that the operation of the main mechanism takes is decisive for the duration in the case of a mechanized process. For the latter , the formula for calculating the duration of the work is as follows:

t = (?q _mach)/(N _n), (3)

where:

q _mash – labor intensity of machinists;

n is the number of shifts per day;

N is the number of workers in the team.

The time that the work of the leading link takes is taken as directive, when teams with an accompanying link of workers are calculated for the mechanized process. The link engaged in carrying out mechanized work is accepted as the lead.

For a mechanized process with an accompanying link of workers, the duration of the work coincides with the duration of the work carried out by the leading mechanism:

t = ?q _mash, (4)

t = (?q _slave +?q _mash)/N _n, (5)

where:

q _slave – labor intensity of workers;

q _mash – labor intensity of machinists;

n is the number of shifts per day;

N is the number of workers in the team.

A desirable condition is the rhythmic work of all workers. Brigades should be formed taking into account:

deadlines for the execution of works;

the technological sequence of their management;

constant workload of all the workers of the brigade, 10-20 workers per foreman;

the composition of the links (qualification and numerical;

labor intensity of work;

Next, let's look at an example with a roof device, for which we will calculate the composition of the brigade based on the data contained in Table 1. Means of small mechanization serve this technological process. The performance of its individual technological operations is regulated by temporary norms, which do not provide for labor costs in machine shifts. For this reason, the brigade is calculated as non-mechanized ^[17].

Table 1. Data for the calculation of the roof installation team

The time t of the work of each i-th link that is part of the brigade is determined:

t_i = q_i/N_i, (6)

where:

q _i – the complexity of the work of the 1st link, people-days.;

N _i is the number of people in the i–th link.

In the case of different working hours of the links, there is an increase in the number of links in the work, the duration of which is high. This increase is a multiple of the ratio ki, which is equal to:

k_i = t_i/t_i^min, (7)

where: 

t _i ^min is the shortest duration of work of the units that are part of the brigade.

Insulation and vapor barrier of the coating are carried out with the participation of identical links, and therefore it is necessary to summarize their labor intensity. That is, the work of the first link will last:

t1 = (20+40) / 2 = 30 days.

The working time of the 2nd link on the laying of cement mortar is equal to:

t2 = 60 / 2 = 30 days.

The working time of the 3rd link on the roofing carpet device is equal to:

t3 = 200 / 2 = 100 days.

The work of the first and second links takes much less time than the work of the third link, therefore, it is necessary to increase the number of links by k times on the device of the roofing carpet:

k = 100 / 30 ? 3.

We accept the following composition of the roof installation team, people.:

- insulator 4 p . – 1 person .;

- insulator 3 p . – 2 people .;

- insulator 2 p . – 1 person .;

- roofer 4 p . – 3 people .;

- roofer 3 p . – 1 person .

Total in the team: 10 people.

As a result of the study, the following conclusions can be formulated on the issue of reducing the duration of construction as a result of increasing the shift to 3 and excluding weekends.

When developing a calendar plan, it is necessary first of all to take into account the results of the calculation and formation of brigades. The given method of calculation and formation of teams at the technological complex of works, allows you to divide the TCR into 3 types of processes and determine the duration of each of them. With the help of this technique, the duration of work for each brigade on separate private fronts is calculated.

In addition, due to the described methodology, TCRs can be divided into several types of processes. The described methodology allows us to determine each process in terms of its duration. It also provides the ability to calculate the time that any team needs to perform work on any of the private fronts.