Parameters for minimizing travel time with GA Spatial and MSO

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Parameters for minimizing travel time with GA Spatial and MSO 

Wed March 16, 2022 09:56 AM

Parameters for minimizing travel time with GA Spatial and MSO

 

In a GA spatial scenario, travel time is always considered to ensure that workers have enough time for work time, drive time and break within a shift, every day. But you may observe in some cases that the solution generated is not optimal with regard to minimizing the overall travel time. This may be due to a “Time limit” too small or a slow convergence, but this may also be due to the model parameters that are not properly set.

 

 

Include Travel Time in Total Time

 

The optimization parameter “Include Travel Time in Total Time?"  should be set to true, if travel time from the labor start location to the first visit of a shift and the travel time from the last visit of a shift to the labor end location should be with the shift hours. Otherwise, the first visit start time will be at shift start time.

 

Minimize total travel time weight

 

By default, the following objectives sorted by importance are considered by the GA spatial optimization model. Priority is defined by an internal parameter weight that can be change in the “Additional Parameters” page.

  1. Maximize the total number of assigned work orders (unperformedCostWeight=100)
  2. Minimize the overall time between the start of the first work order and the end of the last work order (turnaroundTimeCostWeight=10)
  3. Minimize total travel time (Spatial only) (transitionCostWeight=5)
  4. If the flag “Complete High Priority Work First” is “Consider”, assign priority work orders first (highPriorityFirstCostWeight = 1)
  5. If the flag “Match Skills?” is on, try to match work orders to closest skill level possible (allocationCostWeight=0.9)
  6. If secondary labor craft is being used, maximize the number of default laborers used in comparison to the number of non-default laborers [flag “Match on Secondary Labor?”] (secondaryCraftAllocationCostWeight=0.8)
  7. minimize non default work zone allocation [flag "Allow Secondary Work Zone Assignment?"] (nonDefaultWorkZoneAllocationCostWeight = 0.7)

 

By default, travel time is minimized but this is not the most important objective. The most important has normally to be “Maximize the total number of assigned work orders” as otherwise the best/cheapest schedule would be to do nothing.

If the focus is to minimize travel time, you should increase transitionCostWeight (eg  to 20), to be greater than the value of the parameter turnaroundTimeCostWeight.

 

If the parameter is not displayed in the “Additional Parameters” page, you will have to add it in the parameter template with the menu “Spatial Scheduling Template”. Go to “Additional Parameters”, add a new parameter:

  • Parameter Name: Transition cost weight
  • Value: 5 (or 20 if for all new scenario)
  • Parameter ID: transitionCostWeight
  • Type: MODEL
  • Description: Weight for the transition cost objective

Note that a new parameter will only be available in a new scenario.

 

Consider home location for transition cost

 

By default, with the current version (7.6.8/8.1) the travel time from and to home of the worker is not considered in the total driving time to be minimize. To consider it you need to define and set this additional parameter to true:

  • Parameter Name: Consider home location for transition cost
  • Value: false (or true if you want to change the default value at template level)
  • Parameter ID: considerHomeLocationForTransitionCost
  • Type: MODEL
  • Description: if true the travel time between home location and first/last visit is a shift is considered when minimizing travel time. Other only time between visit is minimized.

 

As a limitation, when this parameter is set to true, it enforces on every shift a start and end from home location, so that an interruptible work record cannot be split overnight.

 

 

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