STEP 4: CREATE SCENARIOS
In Step 4, the planner develops scenarios to model various elements of the problem. Each scenario is generated by making one or more of the following changes to the baseline model set-up:
• Adding or deleting products, locations, resources or lanes
• Changing demand allocations
• Adding or relaxing constraints.
The Scenario Summary Sheet (overleaf) records these changes to the baseline model and the results of the scenario model runs. Changes and model results are summarized in terms of demand, resource utilization, lanes, and flow. A diagram visualizes the scenario network. In this way, each scenario represents an alternative network plan.
Often, those managing the network and its resources will be skeptical and reluctant to accept an initial scenario run that predicts significant cost savings from current conditions. These results may be characterized as “too optimistic”. The assumptions, parameters or constraints may be challenged and adjusted until the scenario run yields a more modest improvement – one that the line organization is willing to be accountable for obtaining.
But such a “pessimistic” outcome may be resisted by the planners who rightfully have faith in their validated model. The wise planner anticipates this give and take, and budgets time for optimistic, pessimistic, and most-likely cases. These can then be presented to management to show the likely range of scenario outcomes.
For MTT, several scenarios place the 32 oz upgrade at different plants. Each scenario was run with optimistic, pessimistic, and most-likely cases. Scenario I upgrades a production line in Jonesville (P1). Lanes to branch distribution centers are set up to receive products from Jonesville or Sommersville, with an added constraint that each DC order must be for a full truckload.
When the model was run, the optimizer moved 300,000 cases of 32 oz production from Sommersville to Jonesville. Of these cases, 200,000 were formerly cross-docked through Jonesville to its branch DCs. In terms of resources, Sommersville was relieved of 450 hours of production, while 300 hours were added to Jonesville. The difference is due to the greater efficiency of the newly upgraded line in Jonesville.
Simpsons (DC 23) could not satisfy the full truckload constraint from Jonesville and was reassigned to Sommersville. DCs 11 & 12 – Harrystown and Clinton, along with all the Virginia and West Virginia DCs, received all of their 32 oz products from Jonesville.
Often, some cost categories of concern at the outset of modeling prove to be insignificant once results are in. Or, an important stakeholder may have a fixation on some minor element of network cost. The Cost Summary section of the Scenario Summary Sheet includes these minor or occasionally irrelevant costs in order to remove any concerns or doubts. In our model, crossdocking costs and reduced overtime are insignificant and do not matter to the choice of network plan. Yet the planner includes these to satisfy the concerns and interests of key decision-makers.