Impact of soft logic on the probabilistic duration of construction projects

Current probabilistic scheduling models are based on a single network and assume the sequences (or links or logic) between activities to be fixed. However, some links may be changeable or soft. The presence of a soft link from one activity to another indicates that the execution of these activities has several alternative sequences. This study simulates the duration of an example project by considering uncertain activity durations and probabilistic soft links. The simulated results are compared with those obtained by the program evaluation and review technique (PERT) and three other simulation-based models. The comparisons reveal that the results generated by a simulation are close to those of PERT when the simulation incorporates soft logic. Practical lessons learned by activating soft logic also are discussed.