Application of Relationship Diagramming Method (RDM) for Resource-constrained Scheduling of Linear Construction Projects

The traditional techniques for project scheduling such as Arrow Diagramming Method (ADM) and Precedence Diagramming Method (PDM) are continuously undergoing improvisation in order to replicate real-time construction scenario. Quite often, these methods are criticized for their limited information capturing ability. Relationship Diagramming Method (RDM) proposed by Plotnick in the recent past, is an improved variant of PDM, which can store additional information on relationships that would improve the scheduling process. In addition to basic data on the activities, additional information can be represented through five codes in RDM. Sequencing of activities in a construction project is primarily driven by the construction logic and/or the availability of resources. There is scope for arriving at alternate sequences with varying availability of resources to achieve the objectives of project scheduling as long as the construction logic is preserved. In order to achieve such a resource-constrained project scheduling, additional information on the restraints of the activities are necessary, which can be modelled using RDM through one of the five codes of RDM. The objective of this paper is to explore and exploit the Reason/Why code of RDM. The Reason and Why codes are associated with a restraint and for recording the description respectively. An activity's dependence on a resource has been captured using Reason/Why code in this study. It has been attempted to understand the impact of varying resource availability using an empirical equation on sequencing such resource dependent activities and its effect on critical path. The proposed concept is tested with data from a repetitive high rise construction project. The preliminary results have been well received.