Study On Critical Chain Identification And Buffer Settlement Considering Resource Substitutability

The direct application of TOC to project management led to the development of the 'critical chain'technique which is considered as a great breakthrough in project management. However, there are major disputes along with successful theoretical and realistic researches, such as the indentification of critical chain, the buffer sizing method, and critical chain used in multiple projects. Three core problems are discussed in this paper based on considering resource substitutability.Firstly, the flexible resource's substitutability is defined. Then, models of critical chain identification under different optimization goals such as minimum duration and time-cost tradeoffs are established, while the indexes including substitute rate, substitute cost, and the awards or punishments are introduced into the models. Finally, a scheduling example is given to prove the method's validity, and Genetic Algorithm is usd to solve the after model.After critical chain is identified, buffers have to be obtained. Three comprehensive indexes including resource attributes, project attributes and risk preference of project stakeholders are mentioned. Resource attributes incorporate resource tightness and substitute resource tightness. Project attributes incorporate network complexity and activity importance. In order to validate the feasibility and effectiveness of the proposed buffer sizing model, Monte Carlo simulation technique and Crystal Ball7.0simulation tool are used to compare the model with the two traditional buffer sizing methods. The conclusion is the new buffer sizing model that introduces comprehensive indexes is more realistic and targeted.Based on the former researches, the five detailed steps of critical chain multi-project management are put forward, and then the allocation of bottleneck resources is discussed in detail. There are two cases of bottleneck resources. If activities using bottleneck resource are non-critical chain activity, the comprehensive activity priority calculated by project's importance and activity important is used as the basis of bottleneck resource allocation. If activities using bottleneck resources are activities on critical chains, considering the importance of different projects and the awards or punishments while projects are completed ahead of or behind the deadline, a bottleneck resource-constrained multi-project critical chain scheduling model is built. Particle Swarm Algorithm is used to solve the model, and then an example is used to verify the model and to validate the algorithm.The paper is of realistic and practical means. The academic contributions of present research are as follows:exploring critical chain scheduling problem while flexible resource constrained, enriching the buffer sizing model and making it more targeted, and providing a new way of thinking of critical chain multi-project scheduling problem. The current research is also of practical means through the case study of critical chain's use in a tunnel construction scheduling management, to reduce the project duration and optimal resource allocation.