Effects of overtime work and additional resources on project cost and quality

Delays are an endemic feature of the construction industry. Typically, when a delay occurs in a project, the project manager often expedites progress through activity-crashing with respect to available float and time-cost relationships. An accelerated schedule is thus obtained either by prescribing overtime working hours or by procuring additional resources or a combination of both. However, excessively prolonged overtime work can generate quality problems, such as rework, and additional resources. With this in mind, there is a need for a model to assist project managers with understanding the complex nature of attaining a trade-off between overtime working and the procurement of additional resources. Thus, using system dynamics modelling, the effects of prolonged overtime work on project cost and quality are examined. To overcome project delays, several options representing various combinations of prescribing over-time work and injecting additional resources are analysed. Utility theory is then applied to determine the most appropriate solution for mitigating project delays. The modelling approach offered in this paper should be particularly useful for large projects and for projects on confined sites where potential cost savings and improved quality standards are likely to be the most significant.