A ship loader handling millions of dollars’ worth of bulk material a week was to be replaced. Every day it was going to be out of action would cost the owners a large amount of revenue.
The engineering team had put forward a plan that showed the target shutdown dates could be met and the owner’s team wanted to assess how much confidence they could have in these forecasts.
Working with the owner’s team planner, Broadleaf prepared a model schedule network in Primavera Risk Analysis (PRA) that was aligned with the master schedule. The model was used to identify the major drivers and activity durations that encapsulated the uncertainty in the schedule. Using our specialised approach to limiting bias and ensuring realistic range assessments, we facilitated a workshop with members of the owner’s and engineering teams to assess the uncertainty in the key drivers and task durations. The results were documented and incorporated into the model.
An initial set of model outputs was examined. They showed little chance of meeting the target shut down durations and key milestones. This was inconsistent with the engineering team’s expectations even though they agreed with the schedule model and the uncertainty parameters used.
An examination of the reasons for the unexpectedly pessimistic forecast revealed that some activities had been linked to completion of a large piece of work when in fact they only really depended on the first one or two stages of that activity. In the deterministic model the dates met the required milestones but any appreciable variation in task durations pushed them out.
The model network logic was redrawn with the revised, more realistic, logic and this resulted in a significant reduction in the base duration. This revision was implemented in the master schedule with the same effect.
The revised implementation approach was carried over into detailed preparation for the upgrade and the model was reevaluated. It showed that the project had a high level of confidence in the key milestone dates being met.
A report on the exercise and its conclusions was used to support an application for approval to proceed and this was granted.