Abstract: Classical buffer sizing methods do not take into account the impact of the activity time characteristics when extracting the security time and determining the buffer, thus making the extracted safety time and the determined buffer too large. In order to reflect the time constraints of the activities, a buffer sizing method based on activity time characteristics is proposed. The buffer determination is divided into two aspects:buffer size determination and buffer position determination. Firstly, the safety time extraction ratio is determined by defining the duration elasticity factor to quantify the activity time extraction ratio and the amount of project buffer; then, the centralized and decentralized management of buffer is determined according to the characteristic of period of activities obeying lognormal distribution. The simulation results show that considering the activity time characteristic, the project duration can be shortened effectively, the buffer consumption is reduced, and the project's on-time completion rate is improved.

Key words: critical chain project management, flexible time limit, flexible start time, safety time, Buffer