EFFECT OF LEARNING IN LINE-OF-BALANCE SCHEDULING

Arditi, D., Tokdemir, O.  B. and  Suh, K.  "Effect of Learning on Line-of-Balance Scheduling," International Journal of Project Management, Vol. 19, No.  5, pp. 265-277.

 ABSTRACT: An approach to formulate learning rates and to include them in line-of-balance (LOB) calculations is proposed in this paper.  Learning rates are generated by modifying historical learning rates of typical construction activities and by incorporating the impact of relevant factors such as number of operations in one unit, activity complexity, and job and management conditions.  Fuzzy set theory is used to develop production rules to treat both factual and uncertain information.  An S-type membership function is used to interpret the fuzzy data and to produce adjustment factors that are in turn used to modify consecutive learning rates until an adjusted learning rate is obtained.  The adjusted learning rate is then used to calculate expected worker-hours and activity durations at each unit.  A final LOB diagram is generated using this information.  Different pairs of curves represent the start and the finish times of each activity in sets of units that make use of different numbers of crews.  Learning reduces project duration and resource requirements.  The proposed approach demonstrates the potential for formalizing the inclusion of learning effects into the LOB scheduling of repetitive-unit construction.

SCHEDULING SYSTEM FOR REPETITIVE UNIT CONSTRUCTION USING LINE OF BALANCE TECHNOLOGY

Arditi, D., Tokdemir, O.  B. and  Suh, K.  "Scheduling System for Repetitive Unit Construction Using Line of Balance Technology," Engineering Construction and Architectural Management, Vol.  8, No.  2, pp.  90-103.

 ABSTRACT:  Although line-of-balance scheduling can be superior to bar charts and networks in repetitive-unit construction, there are indications that its use is not widespread.  In this study, the major limitations of the existing line-of-balance methodology are identified and then eliminated by developing a computer program called RUSS.  An effective algorithm that facilitates the implementation of line-of-balance scheduling is developed.  A tool that handles logical and strategic limitations caused by the particular characteristics of repetitive activities is provided.  A learning model is developed and incorporated into line-of-balance calculations.  The program is designed to optimize resource allocation by using multiples of the natural rhythm of activities.  An optimum crew size that guarantees maximum productivity in an activity is used throughout the line-of-balance calculations to achieve cost-optimized schedules.  Non-linear and discrete activities are incorporated into the line-of-balance calculations.  RUSS displays the line-of-balance diagram of every individual path in the unit network.  It is believed that a system such as RUSS will make the line-of-balance method more appealing to contractors of repetitive projects.

PROBLEMS AND SOLUTIONS IN REPETITIVE SCHEDULING

Arditi, D., Tokdemir, O.  B. and  Suh, K.  "Problems and Solutions in Repetitive Scheduling," Journal of Construction Management, Vol. 128, No. 6, pp. 545-556.

 ABSTRACT:  The line-of-balance (LOB) method of scheduling is well suited to projects that are composed of activities of linear and repetitive nature.  The objective of this study is to set down the basic principles that can be used in the development of a computerized LOB scheduling system that overcomes the problems associated with existing systems and creates solutions to problems encountered in the implementation of repetitive-unit construction.  The challenges associated with LOB scheduling include developing an algorithm that handles project acceleration efficiently and accurately, recognizing time and space dependencies, calculating LOB quantities, dealing with resource and milestone constraints, incorporating the occasional non-linear and discrete activities, defining a radically new concept of criticalness, including the effect of the learning curve, developing an optimal strategy to reduce project duration by increasing the rate of production of selected activities, performing cost optimization, and improving the visual presentation of LOB diagrams.

INTEGRATED LINE OF BALANCE SYSTEM FOR HIGH RISE BUILDING CONSTRUCTION

Arditi, D., Srigungvarl P. and Tokdemir, O.  B.  “Integrated Line Of Balance System For High Rise Building Construction”, Construction Management and Economics, 2002, 20, 353-364.

In this study a computerized system to schedule high-rise building construction, is developed by using the line-of-balance technology assisted by an expert system.  Reviewing the recent literature on the techniques available for scheduling and controlling construction projects of repetitive nature, it is found that Gantt charts are inadequate and that there are serious problems with using network methods in such circumstances.  There is evidence that the construction of high-rise buildings has a highly repetitive nature but differs in some respects from other repetitive projects such as pipelines or pavement construction.  Two new concepts have been introduced into line-of-balance methodology to accommodate the special conditions encountered in high-rise building construction.  These two concepts, namely ‘‘flexible” unit networks and “Multi-Level” LOB diagrams have been coded into a scheduling module (LOBPLANS).  A series of databases have been compiled regarding the productivity of resources.  An expert system module (LOBEX) has been developed to facilitate decision-making at network generation level.  The scheduling module, the databases, and the expert system have been organized into an integrated system (CHRISS) by means of communication and command routines that interface between the modules and user input.  A 16-storey building project has been used in testing CHRISS’ performance.  The integrated system proved to be user friendly and reliable.