New Placement Strategy for Buffers in Critical Chain

Abstract

With the introduction of Critical chain by Goldratt in 1997, there has been a lot of research in the field of resource constraint project scheduling problems (RCPSP) and Buffer Sizing techniques. This paper suggests a Buffer management technique which aims at reducing the make span time yet maintaining the stability of the project. In the theory of CCPM it is suggested to reduce the duration of all the activities by half to remove the excess safety time in each activity. The trimmed duration is collected and made available at the end of the project in the form of project buffer which could be used if the project gets delayed. Another buffer called the feeding buffer is added whenever a noncritical chain joins a critical chain. This increases the project duration if the slack of the last activity in the feeding chain is smaller than the feeding buffer. In such cases, this paper suggests the division of the project buffer into parts, fitting each part at the junction of critical and noncritical chains so that the delay occurred because of addition of feeding buffer can be utilized and the duration of project buffer is shortened. The use of the proposed technique has reduced the project duration by a significant value.