Iteration is a common phenomenon in design process which improves the design solution and finalizes it for downstream activities as well as for construction. Though iteration is expected, it imposes rework for the design tasks and often delays design completion. In practice, two basic types of iteration can be seen during design. Firstly, activities with sequential dependency can start early if parameter/information produced by the predecessor is estimable. This estimation might not be accurate enough so that reiteration is needed. Secondly, for coupled tasks in complex design process, design can be finalized by “Sit & settle” or through “Repetition” of tasks involved in loop so that design solution converges to a specified workable range. Taking into account the abovementioned issues, probability of rework has been formulated to develop the proposed simulation model. The simulation model has been examined with a few design tasks and found effective quantifying the amount of rework due to iteration and the overall impact on total design duration. Simulation results depict that most of the rework can be scheduled parallel along with other design tasks so that effect of rework is minimal compared to the amount of time can be saved. The results also show that size and position of coupled design tasks have a great impact on design project. KEY WORDS
Iteration, rework, feedback loop, repetition, sit and settle, simulation model, design completion.