Advanced Schedule Management of Mall Projects

Seo-kyung Won 1, a , Seon-chong Kang 2, b , and Sun-kuk Kim 3,c

1 Dept. of Architectural Eng., Kyung Hee Univ., 1, Kyunggi-do, Korea, 449-701 2 Samsung Engineering & , Kyunggi-do, Korea, 3 Dept. of Architectural Eng., Kyung Hee Univ., 1, Kyunggi-do, Korea, 449-701 a [email protected], b [email protected], c [email protected]

ABSTRACT

Since the projects are scheduled relatively tight in time for the prompt payback of the investment cost, the accuracy of structural framework schedule at the preconstruction stage should be ensured. Hence, delay factors in construction schedule should be thoroughly identified and dealt with at the preconstruction stage. The delay of structural work schedule causes the delay in the overall project schedule, increased overhead cost, and crashing of the overall project. The objective of this paper is to propose an improved management of a shopping complex project schedule, in which the proper scheduling for the work completion in time is ensured by identifying the principal factors for the delay of structural framework and their correlation ranked through a regression analysis.

KEYWORDS : structural work, schedule management, delay factor

1. INTRODUCTION

The developer of a shopping mall wants a prompt payback from the development project by completing the project as soon as possible. Thus, the shopping complex construction projects are scheduled quicker than ordinary construction projects. Moreover, reflecting the current trend of becoming bigger and more complicated, many functional facilities are additionally designed. The contractor must, thus, plan the schedule management very well in advance. Nonetheless, there have been many reported instances of not completing the structural framework in time. As the result, the remaining construction is forced to shorten its completion time, and the overall project is sometimes crashed. This leads to a reduced profit of the projects. This study aims to investigate the delay factors for the structural framework of the shopping complex through case studies of similar shopping complex projects in the past in order to propose a method to complete the construction project in time through the prevention of these delay factors. It is hence hoped that this research can be used as a reference for similar projects in the future by proposing an improved management plan and process.

2. PRELIMINARY RESEARCH

2.1 Literature review

Before carrying the research, similar case studies and previous research reports were examined. The literature review found there have been references on cost reduction through shortening of the construction time such as “Evaluation of Time-Affecting Factors in High-Rise Construction”

1259 (Hong, Young T., et al. 2004) and “Development of an Effective Time Scheduling Mechanism of the Structural Framework for the High-rise ” (Han, Choong H., et al. 2004). Additionally, there was a study to compute the construction duration, which affects the quality and cost of the construction structure, based on actual data estimate, i.e. “The Estimation of Construction Duration for High School Buildings Based on the Actual Data” (Kwon, Dong C., el al. 2004). This study involved a construction of high school buildings and computed the construction duration by including the weather condition of the particular region of the construction in the analysis of variables.

2.2 Cases analysed

This study investigated problem areas for the domestic construction contractors in carrying out mega- size shopping mall construction projects to analyze the causes of the problems and to devise alternative plans. In many cases, the construction duration for these projects is scheduled as quickly as possible by the developer, and the duration of the structural framework takes a very high proportion of the entire construction duration. Additionally, when the duration of the structural framework is delayed in schedule due to any reasons including unavoidable circumstances, the remaining construction is often crashed. As the result, the quality and the cost management become difficult, and both the developer and the contractor can not attain the satisfactory outcome. The actual data of ten domestic shopping mall projects from 2002 to 2004 are collected and analyzed for this study. The types of the data are those factors that can influence the construction duration as listed in the table 1 below.

Table 1. Brief description of project data No DATA No DATA 1 Name of project 14 Duration of earthwork 2 Site area (m 2) 15 Duration of sub-structural work 3 Building area (m 2) 16 Duration of super-structural work 4 Total floor area (TFA, m2) 17 External finishing work 5 Number of basement 18 Internal finishing work 6 Number of floors 19 Working cycle of substructure 7 Underground depth 20 Working cycle of superstructure 8 Total building height 21 Starting date of structural work 9 Framework of substructure 22 Area of basement 10 Framework of superstructure 23 Percentage of basement to total floor area 11 Starting date 24 Shape factor 12 Completion date 25 Average floor height 13 Overall construction duration 26 Delayed time (dy’s) Note) 2002~2004. Data on ten domestic field sites (Samsung Corporation, Inc., Dept. of Construction, Samsung Engineering & Construction)

These potential factors of influence, which are suspected of delaying the framework construction, were selected from the collected data and were prioritized by multi-voting. Among the potential factors of influence, those factors of importance, which can be quantified for the analysis, were selected as listed in table 2, and then more detailed data for each factor were collected again.

Table 2. Prioritization of potential influence factors in shopping mall projects M M M M M M M ran Category Potential influence factors total 1 2 3 4 5 6 7 k Inadequate review of construction documents 9 3 1 3 3 1 1 21 13 Characteristi (drawings, contract, etc.) cs of projects Site condition influencing the construction 9 9 3 9 9 9 9 57 1 duration Application Inadequate documentation of influence factors on 9 3 9 3 3 3 9 39 5 of the actual the duration data Different format for the documentation form at 3 9 9 3 9 9 9 51 2 construction sites

1260 Inadequate data on the productivity by unit cycle 3 9 3 9 3 9 9 45 3 Low reliability 9 9 3 3 3 1 9 37 7 Difficulty in integration and analysis of PMIS 3 3 9 1 3 3 2 23 11 usage Applying an annual average for the computation of 3 3 1 9 1 3 3 23 12 idle days Method of Applying unit cycle by the experiential figure 9 3 3 9 3 9 3 38 6 schedule Lack of computation standard for the duration of 9 3 3 1 3 3 9 45 10 planning completion Selection of lifting equipments based on the 1 3 1 9 3 1 3 21 14 weight Delay in obtaining the construction permit 3 1 3 1 9 9 9 35 9 Delay in the approval of the construction drawings 9 3 9 1 9 3 3 37 8 developer and materials Change in the scope of the construction due to the 9 9 3 1 3 9 9 43 4 budget or decision delay

3. CORRELATION ANALYSIS OF DELAY FACTORS IN FRAMEWORK

3.1 Testing of the hypothesis

These prioritized potential factors of influence among all potential factors of framework construction delay were subjected to detailed data collection. Then, these factors were tested for the variables of analysis in order to examine their validity. A correlation analysis was conducted on the data collected at the aforementioned ten construction sites by using a statistical program package, SPSS. The examples are provided in the following figure 1.

1) percentage of basement to TFA (accepted) 2) shape factor (accepted) Pearson correlation of C1 and C2 = 0.774 Pearson correlation of C1 and C2 = 0.798 P-Value = 0.009 P-Value = 0.006 P-Value : 0.009 < 0.05 P -Value : 0.006 < 0.05

Figure 1. Verification of prioritized potential influence factors (examples of basement percentage and shape coefficient factors)

In addition, such factors for the evaluation of the conditions surrounding the construction site (construction road coefficient), productivity data (the productivity of concrete, formwork, steel reinforcing bars), evaluation of the equipment effect (the number of crane tower used during the structural framework, construction start-cycle for each floor) and other factors of influence on overall construction were analyzed by the method shown in figure 1. The analysis result was used to select or reject the potential factors of delay as proposed in the beginning of this study. Figure 2 lists the important factors of delay, which passed the analysis of correlation test, among all potential factors of delay as proposed in the beginning of this study.

1261 PotentialPotential influenceinfluence factors factors InfluenceInfluence factors factors

 Difficulty in quantitative assessment of the site condition (percentage of basement)  Difficulty in quantitative assessment of the  Difficulty in quantitative assessment of the site condition (percentage of basement) site condition (shape factor)  Difficulty in quantitative assessment of the  Difficulty in quantitative assessment of the site condition (shape factor) site condition (road coefficient)  Lack of documentation for the actual construction  Lack of documentation for the actual construction duration in reference to the plan duration in reference to the plan  Influence of productivity by the construction  Influence of productivity by the construction material type (concrete, formwork, steel bars) material type (concrete, formwork, steel bars)  Influence of working cycle for each substructure  Number of equipments used in the structural  Influence on the construction delay by the framework construction total floor area  Influence of working cycle for each substructure  Influence of working cycle for each superstructure  Influence on the construction delay by the total floor area  Influence on the construction delay by the floorage (building area)  Influence on the construction delay by the ground lot area

Figure 2 Selection of important delay factors in construction

3.2 Computation of the delay rate

This correlation was analyzed for each factor in order to derive a method to compute the delay rate and the relationship among these delay factors. The following four factors were selected based on the importance of the influence on the delay rate as the result of the correlation analysis. Hence, the important factors of influence on the delay of the structural framework construction in the shopping complex construction project are listed as follows.

 total area (D1)  process-cycle for each substructure  percentage of basement (D3)  shape coefficient factor (D4) The following regression equation for the computation of the delay rate is derived based on the data of four factors. Y = 0.433 - 0.000020 * D1 + 0.00407 * D2 + 0.590 * D3 + 0.540 * D4 (1)

4. IMPROVEMENT ON THE SCHEDULE MANAGEMENT FOR A SHOPPING MALL PROJECTS

The delay rate can be computed using the multivariate regression equation, and this computed delay rate can improve the computation of the construction duration by major construction materials. In other words, the important factors, which can cause a construction delay during the initial stage, are identified to calculate the delay rate so that the necessary increase or reduction in the material usage can be computed in advance. Moreover, the standard productivity can be computed so that it can be used with the standard progress chart to select better suppliers or cooperative partners and to eliminate any causes of delay in the construction duration on the part of the suppliers. It works by controlling the construction process based on the framework duration, which is computed on the basis of the standard productivity

1262 appropriate for the project, so that the suppliers or cooperative partners can provide the appropriate personnel and materials in advance before the delay occurs. The next step is to improve on the process of integrating the actual data into the schedule management for a shopping complex project. The planed, actual, and delayed data for the construction by the construction material type is entered as input data by the year, month, and date. Then, the progress feedback is continually entered into the construction management plan during each stage of the construction. Therefore, a better progress plan can be devised on the basis of the quantity and cost used in the construction by entering the input data (weighted by the cost) of the quantity of major construction material type used for each structural part and space of the construction, thus improving upon the existing progress chart by the feedback from up-to-date account settlement reports (now, weighted by the cost of the major construction material type).

Construction cost

Milestones Schedule Breakdown of the construction Breakdown of the construction cost by the quantity of cost by the construction the major construction materials Computation of the material type appropriate weight for (by each floor and structural part) each construction project

Actual data in reference to the plan

Planned progress Actual progress (by the current month (by the current month and the cumulative) and the cumulative)

Report of the progress (by the cumulative graph)

Figure 3 Improvement on the construction progress chart by the feedback from account settlement reports

5. CONCLUSIONS

This paper aimed to help the quality and cost management of shopping mall projects by ensuring the timely and cost-efficient progress of the construction in consideration of the subsequent construction duration through the improvement on the management of the framework construction for a shopping mall projects. Although there have been similar studies on construction projects other than the shopping mall construction, their scope and method are different from this paper. This study focused on the process management of the framework construction as the important research topic based on the unique characteristics of shopping mall construction projects. We intend to build upon the actual data, which were used for the derivation of the proposed computation equation for the delay rate as an alternative for the improvement on the existing schedule management, to collect and analyze more data continually in the future. It is planned to supplement the inadequate actual data of the past and to upgrade the improvement alternative in our follow-up study. We hope that this research will help the construction companies in carrying out a short-term construction project satisfactorily.

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