Quantitative Analysis Model of Construction Project Cost Control and Its Efficacy Verification
Published Online: Mar 19, 2025
Received: Oct 21, 2024
Accepted: Feb 12, 2025
DOI: https://doi.org/10.2478/amns-2025-0463
Keywords
© 2025 Ting Fan, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Construction project cost control is a more important factor in the three major control of the project. Because the construction project cost control work is good or bad, will directly determine the profitability of the project or not. At this stage, China with the continuous improvement of the socialist market economic system, the deepening of opening up to the outside world, especially after joining the WTO to speed up the internationalization process, so that China’s rapid development of economic construction, so in the investment in fixed assets in the construction of an important position in the construction of infrastructure is also in the stage of rapid development in the last 10 years to maintain a strong momentum of growth [1–4]. However, in the economic development of the construction engineering field at the same time also appeared a large number of problems, which is more prominent is that there is no standardized cost management ideas, technology and economic separation, project investment out of control phenomenon often occurs. At present, in China’s construction field there are serious “three super” phenomenon, “fishing project” phenomenon and “rotten building project” phenomenon, these phenomena are related to the various stages of construction projects. These phenomena are all related to the various stages of construction projects, cost loss of control has an inevitable link [5–7]. Correspondingly, China’s project cost management in recent years has made great progress, cost management departments at all levels continue to formulate and issue regulations, methods, rules, etc., in practice, the determination and control of construction costs play a certain role, but this is only in the overall framework of the planned economic system of patchwork, did not play a fundamental role. China’s engineering project cost management theory and methodology research and the international advanced countries compared to there is still a big gap [8–10].
In recent years, China’s rapid development of the construction industry, construction project development is lucrative, many builders have not paid enough attention to the project development cost control issues, or want to control the cost but there is no effective methods and measures. According to the data show that in the past two decades, China’s construction project development costs over the budget of the situation is very common, most of the projects are in the cost overruns, the construction period is extended under the circumstances of the completion of the [11–14]. At present, China’s construction market has begun to take shape, construction projects are moving towards the direction of large-scale, multi-functional and high-grade development, coupled with the introduction of national macro-control policies, the construction engineering market competition is increasingly intensified [15–16]. As the competition in the whole construction market is more cruel and fierce, the whole construction industry enters the micro-profit era, in order to stand out in the competition, each enterprise pays more and more attention to the cost control, and actively seeks for the problems existing in itself. At present, how to minimize the cost, in the required time to complete the project to meet the requirements of the construction, the development of construction engineering products to meet market demand, is an important issue of concern to construction enterprises [17–20].
This paper firstly introduces the basic principle of the Earned Value Method and the basic process of its application, which achieves the purpose of cost control by analyzing the difference between the target implementation and the target expectation. In order to improve the performance of the method, it is combined with the critical path, and the earned value method based on the critical path is proposed, which divides a whole task into several sub-tasks, calculates the relevant parameters of each sub-task, and judges the logical relationship between each sub-task. Finally, the earned value of each sub-task is calculated to obtain the earned value of the overall task. It realizes the grasp of the execution of all sub-tasks, thus controlling the cost required for the implementation of construction projects.
Project cost control involves using an appropriate cost control system to ensure that costs are within expectations. Project cost is the total cost of resources used in a project from start to finish, including employee salaries, materials, equipment, and other expenses. Cost control of a project by a company not only ensures that the project is carried out according to the objectives, but also helps the company to increase its profits and plays an important role in improving the competitiveness of the organization. Project cost control generally consists of the following steps, first of all, to determine the project cost budget, according to the budget to run the project, during the period of time you need to monitor the cost of the project expenditure, to find out the deviation and the reasons for it, and take measures. The project cost control process is shown in Figure 1.
Project cost control flow chart
The operation cycle of the project is generally long, in the whole operation cycle, there are a lot of uncertainties in the impact of factors, and in the decision-making period of the project is not possible to predict all of the project, the slightest error may lead to cost overruns, or even make the whole project aborted, so until the end of the project can not be sure of the final cost of the project. In order to ensure the realization of the goal, the project cost control is divided into pre, during, and post control procedures to complete the entire project cost control process.
There are more technical methods for cost control of engineering projects, and the appropriate means should be chosen according to the specific characteristics of the project. In the existing literature on cost control, the main cost control methods introduced are mostly deviation control method and cost analysis table method, in addition to time, progress, cost method; cost control chart method; linking costs of the crosswalk chart method; cost plan review method; cost of individual cost analysis table method; cause and effect analysis chart method; implementation of corrective measures of cost control table method, and so on.
Cost deviation control method (factor analysis method, image analysis method) is to find out the deviation between planned cost and actual cost through cost analysis on the basis of planned cost. Analyze the reasons for the deviation and take measures to reduce or eliminate the unfavorable deviation so as to realize the target cost method.
There are three kinds of deviations for cost control during project construction: first, actual deviation, i.e., the difference between budgeted cost and actual cost of the project; second, planned deviation, i.e., the difference between planned cost (target cost) and budgeted cost of the project: and third, target deviation, i.e., the difference between actual cost and planned cost of the project. Their calculation formulas are as follows: Cost deviation control method Actual deviation = actual cost - budgeted cost plan deviation = budgeted cost - planned cost target deviation = actual cost - planned cost, the purpose of the project cost control is to strive to reduce the target deviation, the smaller the target deviation indicates that the better the effect of cost control, indicating that the project system is operating in a normal state. The cost deviation control method has the following basic procedures: Determine the range of variation of actual cost according to the planned cost, budgeted cost and minimum cost, and draw the corresponding curve in the cost control chart. According to the cost accounting information, timely tracing points and lines in the chart, drawing the actual cost curve. Analyze the actual cost curve. Net present value (NPV) method Net present value (NPV) refers to the project calculation period of the net cash flow rate of each year (base rate of return) discounted to the beginning of the construction period (the first year of the project calculation period taking into account the time value of money and comprehensive consideration of the project in the entire life of the view, the ability to directly express the net income of the project in monetary terms, can directly illustrate the relationship between the project investment and the cost of capital. In the comparison of multiple programs, calculating the advantages and disadvantages of the net present value of each alternative program is a common method used. The basic steps of the NPV method are as follows: Calculate the NPV of each scenario separately and test it with a discriminant criterion to eliminate the scenarios with NPV<0. Compare the NPV of all options with NPVZO. When the NPV of the cost is the smallest, or the NPV of the benefit is the largest, the best investment plan. Cost analysis table method Cost analysis table method is a method to investigate, analyze and study the construction cost by using the form of table. The form of cost analysis includes several forms such as cost daily report, weekly report, monthly report, cost analysis form and cost forecast report form. The common forms of analysis are monthly cost analysis form, daily or weekly cost statement, monthly costing sheet and final forecast report. In the monthly cost analysis sheet, it is important to indicate the duration of the project, cost items, quantities produced, cost of the project, and unit price of the project. The cost analysis should be made every month for those operating units that may be controlled. The classification of cost and expense items must be consistent with the construction budget (cost plan) in order to analyze and compare, to find out the items that are higher than the planned cost and expense, and to take targeted measures to reduce the cost of the project. Monthly cost analysis sheet Daily or weekly cost statement Project managers should understand the daily and weekly progress and costs of the main works, quickly identify any problems during project implementation, and take effective measures to solve them in time. Therefore, should be made daily, weekly cost analysis table. The daily and weekly cost statements should be timely, detailed, and accurate. They usually only include the cost of labor, machinery operating costs, and the amount of work completed. At the construction site, the daily or weekly cost statement should normally be delivered to site management on a daily basis, along with the daily progress statement of the project. Monthly Costing Statement and Cost Forecast Statement These two statements should include the main contents of the project name, the amount of costs incurred, to the completion of the project is still required to project the amount of costs, the contract budget costs, profit and loss projections, etc. This statement should be completed at the same time as the month-end accounting books are closed. This statement’s accuracy over time is increasing. It is one of the main elements of cost control and also the main task of enterprise cost accounting.
Earned value (EV), the actual amount of work done at a given stage in the implementation of a project and the hours worked (or costed) at the budgeted rate. Also called the budgeted cost of completed work. Earned value method is mainly used for the performance management of the project, its fundamental content for the comparison of the project implementation process of the actual and planned differences and similarities, attention is paid to the actual individual project tasks, in terms of content, time, cost, quality and other aspects of the difference with the plan, and then according to these differences, you can predict, adjust the remaining tasks in the project. The basic information it compares is the value of work at a certain stage in the construction plan with the value of the content of the actually completed project at the same stage, as well as the actual corresponding expenditure costs, which is used to judge whether the construction costs and construction progress are consistent with the plan and to reach the performance of this stage.
Earned value method, also known as earned value method or deviation analysis method [21], is a method used to analyze the difference between target implementation and target expectation. Earned value method by measuring and calculating the budgeted cost of the completed work and the actual cost of the completed work, compared with the budgeted cost of the planned work to get the cost deviation and schedule deviation of the project, so as to achieve the purpose of judging the implementation status of the project cost and schedule plan. It has three basic parameters: The budgeted cost of the planned workload, referred to as BCWS, BCWS refers to the budgeted man-hours and costs required for the workload required to be completed by the plan at a certain stage in the project implementation process, also known as the planned value (PV). The formula for calculation is:
BCWS mainly reflects the workload that should be completed by the program. The actual cost of completed workload, referred to as ACWP, also known as the actual cost (AC). ACWP refers to the man-hours or costs consumed by the workload actually completed at a certain stage in the process of project implementation, mainly reflecting the actual consumption indicators of project implementation. Budgeted cost of completed workload, referred to as BCWP, BCWP refers to the workload actually completed at a certain stage in the project implementation process and the man-hours or costs calculated according to the budget, i.e. earned value (EV). The calculation formula is:
The basic idea of Earned Value Method is to introduce the “Earned Value” as an intermediate variable in the project implementation process, so as to control the progress and cost in the project implementation process, and to draw relevant conclusions through the analysis, to make a scientific prediction on the performance evaluation of the current project status and the subsequent status, and to give early warning of possible abnormalities in advance, so as to facilitate the proposal of practical and feasible control programs. It will give early warning of possible abnormalities, so as to propose practical control programs.
Through the setting of the above three basic parameters, four performance indicators are constructed in Earned Value Management to measure the time status of the project:
Cost Variance (CV) is the difference between the budgeted plan for the amount of work accomplished and the actual costs incurred during the inspection period. It is calculated by the formula:
If
If
If
The progress variance (SV) is the difference between the budgeted cost of the actual and planned workload completed at the date of inspection. The formula for calculation is:
If
If
A
The Cost Performance Indicator (CPI) is the ratio of the budgeted plan to the actual costs incurred for the workload completed during the inspection period. It is calculated using the formula:
If
If
If
The Schedule Performance Indicator (SPI) is the ratio of the budgeted cost of the actual and planned workload completed at the date of the inspection. The formula is:
If
If
If
By analyzing the available data, the Earned Value Method can also be used to estimate the status of subsequent portions of the project, creating Earned Value Method predictors that can be used to analyze the status of subsequent uncompleted portions of the project:
The Estimate at Completion (EAC) is an estimate of the total cost to complete the project based on the current level of cost performance. The formula is:
The Estimate to Complete (ETC) is an estimate of the cost of the remaining work elements of the project with reference to the current level of cost performance. It is calculated using the formula:
It can also be calculated on the basis of the cost utilization rate of the project so far:
The BAC in the formula is the initial total budget data for the project.
When applying the earned value method in project management, the following basic processes should be followed: By organizing project related information and then setting project objectives. Determine the observation and monitoring points for process control in the project plan. Determine the BCWS at the monitoring points based on the cost plan of the cost budget. Count the actual value of the project implementation cost at the time point of the monitoring point and calculate the budgeted cost corresponding to the actual volume of work based on the cost budgeted data of the project, i.e., determine the ACWP and BCWP. Calculate the cost and schedule deviation, or cost and schedule execution indicator, as the project implementation phase performance, and also use it to determine the project implementation status. Find the reasons for the out-of-scope deviations and formulate corrective measures to rectify the project implementation problems. The above process, the use of the earned value method in the implementation of the project must be the steps, in practice, but also need to be based on the actual characteristics of the project and the specificity of the data transmission, processing, analysis, use of targeted operations.
Critical Path Method (CPM) is a very effective and practical method for engineering management [22], its working principle is to firstly decompose an overall project to the smallest sub-activities through the WBS work breakdown structure, and anticipate and calculate the working time of the sub-activities, including the earliest start time, earliest finish time, latest start time and latest finish time of each sub-activity, and then organize the logical relationship and sequence between the sub-activities to form a network diagram of the project, from which a path with the longest working duration in the project is found, which is the critical path. Then organize the logical relationship and sequence between the sub-activities to form a network diagram of the project, from which a path with the longest work duration in the project is identified, i.e. the critical path, and the detailed steps are as follows. According to the logical relationship between the sub-activities to draw a network diagram, each node indicates the event, the arrow indicates the activity, so that you can have a comprehensive and holistic concept of the full cycle of the project. In the activity that is the arrow to indicate the time required to carry out each activity. Network diagram from left to right, calculate the earliest end time of each sub-project (EF), EF is equal to the sub-project’s earliest start time (ES) and the duration of the sum. The time of the remaining sub-projects is calculated using this method, and the final result is the time required for the completion of the entire project. Network diagram from right to left, calculate the latest finish time (LF) of each sub-project based on the time required for the project, and then calculate the latest start time (LS) of each sub-project by dividing LF by the duration of the sub-project. The difference between the latest start time (LS) and the earliest start time (ES) or the difference between the earliest finish time (EF) and the latest finish time (LF) represents the working time difference of the sub-project. According to the calculation of the working time difference, the data is zero, which means that the sub-project is on the critical path, and all the sub-projects with zero time difference finally produce the critical path of the whole project.
The critical path and non-critical path of the project are differentiated, and the second level of Earned Value Management Analysis is proposed [23], i.e., the Earned Value Method can be applied at any level of the WBS. The first step is to divide all the tasks into many sub-tasks, then calculate and determine the relevant parameters of each sub-task, and at the same time determine the logical relationship between the sub-tasks, and finally calculate the Earned Value of each sub-task to arrive at the Earned Value of the whole task. In this way, project managers can have a clear grasp of the implementation of all sub-tasks, conduct a thorough analysis of the entire task, and effectively control the cost of project implementation.
The person in charge of the project control, the first to determine the project’s critical path, and the entire task of the critical path and non-critical path on the activities to distinguish, and will focus on the supervision of the activities on the critical path in the control process need to apply the second level of the earned value of the project management, based on the critical path of the basic process of the will be the value of the management of the analytical method is shown in Figure 2.
Flowchart of project earned value management
One of the most important features of this article is that when analyzing the earned value of a project, the critical path and the non-critical path are separated, and two other parameters are introduced on the basis of the three basic parameters of the earned value management analysis, namely BCWPk and BCWPnk. where BCWPk refers to the earned value of activities on the critical path of the project, while BCWPnk refers to the earned value of activities on the non-critical path of the project. Similarly, BCWS differentiates in the same way. Using the above parameters it is possible to calculate the schedule deviation on the critical path and non-critical path of the project.
The specific formula for calculating schedule deviation on the critical path:
Can be based on the project’s overall progress deviation and critical path progress deviation can reflect the progress of the project where the checkpoints are located, specifically the following situations. The entire project progress deviation SV is greater than the value of 0, and SVK is also greater than the value of 0. The overall progress of the project is ahead of the critical path progress is also ahead of the critical path, indicating that the project running activities are faster than the planned speed, the project can be completed earlier, in this case, you need to pay attention to the cost of the project whether there is an overrun of the situation. The progress deviation SV of the whole project is greater than 0, while SVK is less than 0. The overall progress of the project is ahead of schedule, but the progress of the task activities on the critical path is lagging behind than expected, from which there is out because the task activities on the non-critical path are ahead of schedule than expected, in which case, the project should redeploy its sources of supply to the tasks on the critical path, so that the project can be completed as soon as possible. The project can be completed as soon as possible. The progress deviation SV of the whole project is less than 0, while SVK is greater than 0. The whole project is behind the expected development, but the task activities on the critical path are ahead of the expected development, from which the task activities on the non-critical path are longer than the expected time of the plan to lead to the emergence of the phenomenon, in which case, it is necessary to consider ways to deal with the non-critical path according to the specific time of the task activities. Carry out time to consider ways to deal with, if the path of the task activities in the latest start time, then you can not consider the situation: if the task activities have exceeded the expected plan for the latest start time, then the need for appropriate deployment of resources to the activity. The progress deviation SV of the whole project is less than 0, and SVK is also less than 0. The whole project is lagging behind the expected plan, and the activities on the critical path are also lagging behind, in which case, additional human resources or equipment should be assigned to the lagging tasks, so as to shorten the duration of the tasks on the critical path, and to improve the project’s progress.
A bridge construction company has undertaken the construction of 12 bridges in the past three years, and the project cost overruns of five bridges are related to schedule delays. A bridge construction project is selected as an example.
Before drawing the network plan, firstly, according to the requirements of the construction organization and process flow, to clarify the relationship between the specific work of mutual dependence or constraints. That is, to clarify the work package before the start of construction, must be the first to complete what immediately before the work, and the work of the parallel construction links. Clarify the relationship between work and work, for the drawing of the network plan can clearly reflect the actual situation of the bridge construction project, is very important step. Because if there is a mistake in the representation of work relationships, then the calculation of time parameters will also produce errors, which will also affect the determination of the critical path and the prediction of the total duration of the project. Once the work relationships have been clarified, the duration of each specific work package is estimated. The reliability of work duration estimation has a significant impact on the overall quality of the project program.
This paper then considers three conditions based on the WBS decomposition chart and the construction sequence: which work packages need to be performed before the completion of a particular work package, which work packages need to be performed after the completion of a particular work package, and which work is performed in parallel with that work. The duration of the work is determined according to the time required under normal conditions, and the relationships between the work tasks for the bridge construction project are drawn. The specific relationship content is shown in Table 1.
Bridge construction project work relationship table
| Job code | Work package name | Tight work | Duration (day) |
|---|---|---|---|
| A | Bridge, channel | 24 | |
| B | Precast beam field | 24 | |
| C | Box girder prefabrication | B | 92 |
| D | Hollow plate prefabrication | B | 66 |
| E | Old bridge demolition | A | 48 |
| F | Foundation of the bridge (hole grouting, column, beam) | E | 128 |
| G | Support stone | F | 12 |
| H | Beam mounting | G | 32 |
| I | Reaming and wet seam | H | 15 |
| J | Bridge dress | I | 32 |
| K | Wall guard | I | 23 |
| L | Expansion joint installation | J, K | 9 |
| M | Sideway board installation | J, K | 12 |
| N | Marking line | L, M | 2 |
| O | The bridge is demolished by the way | N | 16 |
According to the working relationship Table 1, to understand the duration of each process and the order before and after, according to the principle of drawing network plan diagram, draw the network plan diagram of the bridge construction project, network plan diagram as shown in Figure 3. Finally, through the calculation of network planning time parameters, it can be determined to complete the total duration of the project, the earliest start time and the earliest possible end time of each sub-work, the latest must start and the latest must end time, as well as before and after the work of the various time differences, to find out the key work and the key lines in the network planning diagram.
Network plan diagram
The result of activity time calculation is shown in Table 2, by analyzing Table 2, the total time difference of each work package on the critical path is 0 and it is the line with the longest duration from the starting point to the end point of the network plan, while the total time difference of A, E, F, G, H, I, J, M, N, and O are all 0. Therefore, the critical path of the project is the right-of-way bridge approach project, the demolition project of the old bridge, the lower foundation project of the bridge, the support seat cushion stone work, girder installation work, hinge joint and wet joint work, bridge deck paving work, sidewalk panel installation work, sign and marking work, and right-of-way bridge demolition work.
Activity time calculation results
| Job code | Node number | Earliest starting time | Earliest end | Late start time | The end of the day | Total jet lag | Critical path | |
|---|---|---|---|---|---|---|---|---|
| i | j | ES(i,j) | EF(i,j) | LS(i,j) | LF(i,j) | TF(i,j) | ||
| A | 2 | 7 | 0 | 24 | 0 | 24 | 0 | ⎷ |
| B | 2 | 3 | 0 | 24 | 100 | 124 | 100 | |
| C | 3 | 4 | 24 | 116 | 124 | 216 | 100 | |
| D | 3 | 5 | 24 | 98 | 144 | 218 | 120 | |
| E | 7 | 8 | 24 | 75 | 24 | 75 | 0 | ⎷ |
| F | 8 | 9 | 75 | 205 | 75 | 205 | 0 | ⎷ |
| G | 9 | 10 | 205 | 216 | 205 | 216 | 0 | ⎷ |
| H | 10 | 11 | 216 | 246 | 216 | 246 | 0 | ⎷ |
| I | 11 | 12 | 246 | 259 | 246 | 259 | 0 | ⎷ |
| J | 12 | 13 | 259 | 289 | 259 | 289 | 0 | ⎷ |
| K | 12 | 14 | 261 | 281 | 282 | 292 | 11 | |
| L | 13 | 15 | 286 | 300 | 290 | 304 | 4 | |
| M | 13 | 16 | 292 | 301 | 292 | 301 | 0 | ⎷ |
| N | 16 | 17 | 301 | 303 | 301 | 303 | 0 | ⎷ |
| O | 17 | 18 | 303 | 318 | 303 | 318 | 0 | ⎷ |
Therefore, it is important to distinguish between the different paths when analyzing the earned value report afterwards. If a specific project is on the critical path, a negative Earned Value should be given extra attention by the project manager. Since the total duration of all projects on the critical path is critical to the determination of the total duration time, and thus on this line, the maneuvering time is zero, on this line in any one of the construction process if there is a delay in the schedule, will extend the total duration. Correspondingly, advancement of the schedule will reduce the total duration. So in this line, any one of the minor or major deviations, are likely to increase the total cost of the project or delay the schedule, or even the project will go bankrupt; if it is a non-critical path on the work of the minor deviations, then as long as it does not affect the total duration and total cost of the project, can not be adjusted. Unless the delay exceeds the maneuvering time, then the project leader should pay attention. Because under certain conditions, the non-critical path can be turned into a critical path, which in turn affects the overall project process.
The budgeted cost of a bridge construction project mainly includes direct costs, indirect costs and taxes paid. Among them, project direct cost includes: direct engineering cost and measure cost. In fact, project cost control based on critical path earned value method is mainly project direct cost control. Project direct engineering costs include labor costs, material costs, machinery costs, and subcontracting costs. Specifically, each work package layer is decomposed into specific sub-projects, i.e., the most basic unit, which are decomposed into labor, machinery and other budget costs. Taking Work Package A (Right-of-way Bridge and Approach Road) as an example, its cost is composed of three sub-projects, i.e., Temporary Road, Temporary Occupancy, and Temporary Right-of-way Bridge Installation. Therefore, when we calculate the budgeted cost of this work package in September, we combine the budgeted cost of September formulated by the company, and count the labor cost, machinery cost and subcontracting cost of these three items of the project, and finally total the budgeted cost of this work package. The costs of the other work packages on the project, as well as their subcontract costs, can be tallied. The direct project budget cost of each project of the bridge construction project is shown in Table 3, and it can be seen from the table that the project budget cost of project C is the highest, which is 5390087 yuan.
Budget cost (Yuan)
| Job code | Labor cost | Materials cost | Mechanical charge | Subcontract charge | Tot |
|---|---|---|---|---|---|
| A | 594198 | 0 | 713063 | 1069565 | 2376826 |
| B | 0 | 300009 | 0 | 199989 | 499998 |
| C | 0 | 2083942 | 0 | 3306145 | 5390087 |
| D | 0 | 24 | 0 | 1028894 | 1028918 |
| E | 0 | 0 | 0 | 810287 | 810287 |
| F | 10230 | 1620774 | 12506 | 1840152 | 3483662 |
| G | 0 | 5939 | 0 | 147295 | 153234 |
| H | 728381 | 1092598 | 849784 | -20 | 2670743 |
| I | 0 | 36355 | 0 | 219428 | 255783 |
| J | 0 | 573492 | 0 | 382336 | 955828 |
| K | 0 | 160135 | 0 | 740862 | 900997 |
| L | 0 | 160813 | 0 | 107211 | 268024 |
| M | 0 | 55991 | 0 | 37312 | 93303 |
| N | 0 | 0 | 26 | 515806 | 515832 |
| O | 0 | 0 | 0 | 216950 | 216950 |
The evaluation of the earned value method is for the cost of each project during the period from the start of construction to the monitoring time point. If the evaluation and calculation are carried out in real time, on the one hand, the progress advancement is not obvious, and the evaluation can not see the obvious effect, and on the other hand, real-time collation of data and analysis of the report need to take up manpower and material resources. Therefore, by matching the progress plan and budget plan, the earned value method monitoring node of the project implementation process is determined at the end of each month. Table 4 shows the values of the three basic parameters (BCWS, BCWP, ACWP) of the earned value method for the whole project and the critical path.
The three parameters of the entire project earning method
| Year | Month | Whole project | Critical path | ||||
|---|---|---|---|---|---|---|---|
| BCWS | ACWP | BCWP | BCWSk | ACWPk | BCWPk | ||
| 2020 | 1 | 6.54 | 7.18 | 6.08 | -- | -- | -- |
| 2 | 7.82 | 8.59 | 7.69 | -- | -- | -- | |
| 3 | 85.84 | 98.1 | 82.73 | 40.16 | 37.17 | 40.68 | |
| 4 | 159.45 | 180.98 | 178.67 | 78.64 | 72.93 | 76.45 | |
| 5 | 222.09 | 250.86 | 251.61 | 110.12 | 106.81 | 104.2 | |
| 6 | 1057.85 | 1185.38 | 1012.64 | 529.82 | 533.24 | 524.23 | |
| 7 | 1826.51 | 2037.48 | 1820.59 | 930.5 | 937.98 | 951.32 | |
| 8 | 4064.82 | 3943.15 | 3866.95 | 2119.29 | 2042.32 | 2083.52 | |
| 9 | 4976.98 | 4903.07 | 5126.27 | 2609.59 | 2567.14 | 2553.71 | |
| 10 | 6090.14 | 6060.26 | 5851.22 | 3171.92 | 3143.22 | 3152.31 | |
| 11 | 7615.52 | 7602.21 | 6727.19 | 3969.35 | 3916.76 | 4087.72 | |
| 12 | 8332.9 | 8237.39 | 9033.49 | 4341.46 | 4289.93 | 4542.6 | |
| 2021 | 1 | 10009.36 | 9695.82 | 9678.32 | 6017.9 | 5933.65 | 6195.78 |
| 2 | 10256.56 | 9920.6 | 9461.66 | 6265.17 | 6159.75 | 6246.37 | |
| 3 | 10516.55 | 10162.41 | 10516.73 | 6525.14 | 6406.24 | 6525.18 | |
| 4 | 11055.02 | 10679.08 | 11055.03 | -- | -- | -- | |
| 5 | 12429.54 | 11995.88 | 12429.46 | -- | -- | -- | |
Figures 4 and 5 show the changes of the three basic parameters of the project and the critical path, respectively. From Figures 4 and 5, it can be seen that during the construction of the project, the overall project cost control is relatively reasonable, thanks to the reasonable planning of the construction plan in the early stage and the targeted corrective measures in the process. In addition, compared with the gap between the three major parameters of the critical path, the fluctuation of the whole project is greater, especially in March 2021, the gap between the two values of BCWS and ACWP of the whole project is 3,541,400 yuan, and the gap between the two values of BCWS and ACWP of the critical path is only 1,189,000 yuan, and its gap is only one-third of the whole project. Overall, the control of the critical path is more in place.
Changes in the three basic parameters of the project
Changes in the three basic parameters of key paths
Figure 6 shows the total cost of the project predicted on the basis of the deviation of the entire project for each month, the red straight line target cost control line, from the scatter distribution in the figure can be seen in the early part of the project there has been a risk of over-budgeting, and even the possibility of substantial over-budgeting. Through the process of evaluating the calculation of indicators, early warning systems, and analyzing the causes by region, to achieve better cost control. For example, in December 2020, it was shown that the forecast cost was much lower than the target cost, which was only 112.5 million yuan, and the reason for this was because some of the cost of construction materials and machinery had not been paid. Through the analysis and control of each node, the ultimate goal of cost control is achieved.
Cost forecast
Figure 7 shows the distribution of the duration forecast based on the critical path. From the figure, it can be seen that during the implementation of the project, the project team pays great attention to monitoring the progress of the critical path. The longest time that the critical path exceeds the planned duration is 20 days, and the longest time that is shortened is 18 days, which is mainly due to the imbalance of resource deployment (manpower, material and machine) on the critical path. Most of the time, the deviation can be controlled within 8 days, which is within the controllable range. At the end of the project, the schedule was gradually adjusted to fit the planned duration, and the task of completing and delivering the project on time was finally achieved. In summary, this paper adopts the critical path based earned value method to evaluate and control the cost and schedule of the construction process, which can play a good role in cost control in the actual project. Especially because the typical nodes of each month are analyzed, which makes the process management very reliable, and the corrections and adjustments are very timely, and achieves the goal of optimizing the construction and controlling the cost-schedule.
Progress prediction
In this paper, the critical path earned value method is applied to cost control of bridge A construction project of a bridge construction company, which helps the company to solve the problem of cost control of this construction project.
In the process of construction of this project, the overall cost control is reasonable due to the reasonable planning of the construction plan in the early stages. The fluctuation amplitude of the whole project about the three main parameters is larger than that of the critical path, and in March 2021, the gap between the two values of BCWS and ACWP of the whole project is three times of the gap between the two values of BCWS and ACWP of the critical path. It is concluded that the three major parameters of the project are more controlled by applying the critical path earned value method proposed in this paper.
There is always a risk of over-budgeting in the early stage of the project, and through the implementation of the method in this paper, the predicted cost in December 2020 is only 112.5 million yuan, which is far below the target cost. The goal of cost control was achieved. The longest and shortest time that the critical path exceeded the planned duration were 20 and 18 days, respectively. Most of the time, the deviation can be controlled within 8 days, which is within the controllable range. In summary, this paper adopts the earned value method based on the critical path to control the cost and schedule of the construction process, which plays a good role in controlling the cost of the project, achieves the purpose of optimizing the construction, and verifies the effectiveness of the cost control method proposed in this paper.