Project Time Control in Building Construction
CHAPTER ONE
OBJECTIVE OF THE STUDY
Erel and Raz (2000) state that the project time control cycle consists of measuring the status of the project, comparing to the plan, analysis of the deviations, and implementing any appropriate corrective actions. When a project reach the construction phase, monitor and control is critical to deliver the project success. Project monitoring exists to establish the need to take corrective action, whilst there is still time to take action. Through monitoring the activities, the project team can analyze the deviations and decide what to do and actually do it (Gardiner and Stewart 2000,p252). The purpose of monitor and control is to support the implementation of corrective actions, ensure projects stay on target or get project back on target once it has gone off target (Erel and Raz, 2000,p253).
- a) Do unstarted activities really have to await the completion of other activities before they can start? If no, start the activities
- b) If an activity has to wait for the completion of other activities, can that activity be broken down into sub-activities and some of the sub activities completed at an earlier date? If no, break down the activity into sub-activities and start the urgent one at once.
Herroelen and Reyck (1999) also state that managers have to tackle the challenging problem of scheduling activities to minimize the project duration, in which the activities (a) are subject to generalized precedence relations, (b) require units of multiple renewable, non-renewable and doubly constrained resources for which a limited availability is imposed, and (c) can be performed in one of several different ways, refected in multiple activity scenarios or modes.
Optimal timing
Considering optimal timing of project monitoring and control points is significant to success (Falco and Macchiaroli,1998). Falco and Macchiaroli suggest that we should determine the optimal frequency of the monitoring and reviewing to different activities in different stages. It can help us to efficient monitor and correct control so as to reach time and cost target.
Crashing
In recent years, network crashing was developed along with the project time control method (PRC ) for planning and controlling large scale project. The purpose of crashing is the minimization of the pessimistic time estimate in PERT (Program Evaluation and Review Technique) networks by investing additional amounts of money in the activities on the project time control . Sometimes, crashing methods are required to combine in the monitoring and controlling process when the duration of the activity that has to be completed within a specified time (Abbasi and Mukattash,2001,pl81).
CHAPTER TWO
INTRODUCTION
Non-stationary construction processes are commonly characterized by a great number of unexpected incidents and changing boundary conditions as well as by enormous time and cost pressure. In order to ensure the efficient use of valuable resources in spite of these challenges, a scheduling technique is needed that allows for active control and steering. Planning methods that feature adequate adaptability and support the description of parallel processes, unexpected incidents, and stochastic and fuzzy parameters are therefore necessary (Hohmann 1997).
Thus, modern simulation tools can be applied with increasing success. Up to now, these tools for the optimization of construction and logistical processes are predominantly used in the start-up phase of a project. Projects are often affected by unscheduled constraints and limitations, especially in the erection phase, that give reason to deviate from the formerly optimized plan and to find new current solutions.
The concept presented in this paper was developed with particular attention to time control. Experience in this field demonstrates that bar diagrams are still the predominant tools on most construction sites. Even critical path methods are uncommon. Simulations however, can provide much more information, such as the machine’s productivity, possible hidden capacities, and reasons for reduced output (Hohmann 1997).
In order to meet the aforementioned requirements of daily construction business, the application of simulation tools could be extended from the planning phase to the erection phase. A more specific and dynamic data base is needed to effectively address this challenge.
CHAPTER THREE
DATA SOURCES
In discussing the available data sources, an evaluation of the usable instruments must be done. Up to now most research projects develop and analyze data gathered from one type of source, for example RFID. But the reality in construction varies so much that different techniques of data gathering have to be combined.
A suitable mix of these techniques will be established within the ongoing research project. Therefore, different sources of information are identified parallel to the process modeling that in total give significant information about the current state of the construction (Bargstädt 2008).
CHAPTER FOUR
CURRENT STATUS
During the last thirty-five years, a number of authors have tried to define the mathematical expression for defining cash-flow diagrams, which proved an extremely demanding task for a number of reasons lending the ‘search’ for a universal solution still unfinished. A typical diagram presenting the cumulative cost in relation to time for construction projects, here reduced to the ratio of 100% v. 100%, resembles the letter «S» as we have mentioned in the preceding chapter. At the beginning of any project, during the project mobilization and organization phases, the costs grow at a slow pace. Later, when most of the work teams are engaged in the project (in various locations), the costs grow at an approximately constant rate (a relatively straight line in the center of the diagram). Towards the end of the project, when the work teams have finished their jobs, the cost growth decreases. Most of the mathematical models are based on this assumption. Over time, authors from all over the world, working under quite different conditions, have tried to define a universal cost flow forecasting model.
CHAPTER FIVE
CONCLUSION
The data about a total of 24 completed construction projects were collected for research purposes. In addition to the basic data about the construction buildings in question (type of building, period of construction, agreed and actual cost of construction, agreed and actual duration of construction), the data about monthly (scheduled) costs of construction were added, on the basis of which the necessary data for modeling a time-cost curve for each of the completed projects were obtained.
As it was expected, deviations between the planned and the actual timeframes, as well as the planned and the actual costs of construction occurred in most cases.
The risk factor data and the impact of risks on the actual final cost of construction and the actual final timeframe were collected as well. The data were obtained on the basis of interviewing various participants in the construction process (engineering supervisors, investors, architects and contractors) who defined the type and the intensity of impacts during the construction.
In the process of modeling the s-curve manifold statistical methods and techniques were utilized. We used several statistical packages for data processing, mainly the SPSS packages. Several different models have been considered, yet the polynomial curve of the following shape proved best for statistical purposes.
The survey shows that most projects encounter cost and time over-runs (Williams Ackermann, Eden, 2002,pl92). According to Wright (1997)’s research, a good rule of thumb is to add a minimum of 50% to every time estimate, and 50% to the first estimate of the budget (Gardiner and Stewart, 1998, p251). It indicates that project is very complex and full of challenge. Many unexpected issues will lead the project cost and time over-runs. Therefore, many technologies and methods are developed for successful monitoring and control to lead the project to success. In this article, we will discuss in the construction phase, how can a project manager to be successful in time and budget control. Another part we will discuss what pitfalls will wait for the manager in his endeavors to monitor and control the project.
For the purpose of achieving time and cost target, the manager need to set up an efficient management framework including: reporting structure, assessing progress, and communication system. The employees’ responsibility and authority need to be defined in the reporting structure. The formal and informal assessing progress can help getting a general perspective between reality and target. It is significant to help identify what is the risk and should be monitored and controlled. Project success is strongly linked to communication. The efficient communication system benefit for teamwork and facilitate problem solving ( Diallo and Thuillier, 2005 ).
In construction phase, many activities are carried out based on the original plan. It is need to know what kind of activities or things are most likely to lead the project delay and disruption. Therefore, the first step is ranking the priority of the activities. Because the duration of a project is determined by the total time of activities on critical path, any delay in an activity on the critical path will cause a delay in the completion date for the project (Ackermann Eden, Howick and Williams,2000,p295). Therefore, the activities on critical path should firstly to be monitored and controlled. Secondly, monitoring the activities with no free float remaining, a delay in any activity with no free float will delay some subsequent activity inevitably. These subsequent delays will discomfit the resource schedule significantly. Some resources are unavailable because they are committed elsewhere. Thirdly, monitoring the activities with less than a specified float, because if an activity has very little float, it might use up the time before control decision is made once such an activities has a variance with the target. Fourthly, managers should monitor high risky activities. High risky activities are most likely to overrun or overspend. Fifthly, managers should monitor the activities using critical resource. Some resource is critical because they are very expensive or limited (Cotterell and Hughes, 1995)
REFERENCES
- Bargstädt H.-J. and K. Ailland. 2008. Capturing the real time state of construction for simulation,IABSE Conference, Helsinki, Finland, Conf. Proceedings.
- Bayer J. 2003. Simulation in der Automobilproduktion, Springer, Berlin.
- Beißert U., M. König, D. Steinhauer, and H-J. Bargstädt. 2007. Constraint-Based Simulation of Outfitting
- Processes in Shipbuilding and Civil Engineering, 6th EUROSIM Congress on Modelling and Simulation, Conf. Proceedings, Ljubljana, Slovenia.
- Buchhop E. 2007. Zeitliche Erfassung von Kernprozessen als Teil der Prozessanalyse, bdvb-Award Geschäftsprozess-und Projektmanagement, CT Salzwasser-Verlag, Bremen.
- Bundesministerium für Verkehr, Bau- und Wohnungswesen. 2004. Richtzeichnungen für Ingenieurbauten, Verkehrsblatt-Verlag, Dortmund.
- Chen Z., H. Li and C.TC. Wong 2002. An application of bar-code system for reducing construction wastes,
- Automation in Construction, Vol. 11, no. 5, pp. 521–533.
- Ergen E., B. Akinci, and R. Sacks. 2007. Tracking and locating components in a precast storage yard utilizing
- radio frequency identification technology and GPS, Automation in construction, Vol. 16, pp. 354–367, 25.07.2006.
- Hohmann G. 1997. Von der Netzplantechnik zur Simulation – Analyse von Bauprozessen mit Hilfe von