Tuning Time Window Effect in Multistop Sequencing

In multistop sequencing logic, OTM considers order time windows and calendars at the stop locations while generating stop sequences for a consolidated shipment. This helps in identifying and rejecting many time infeasible sequences at an early stage in sequencing. To achieve this, OTM computes the effective time windows at the stops based on order time windows and work period ranges of the calendars at the stop locations. The following shows how these effective time windows affect sequencing of stops.

1. No overlap in effective time windows:

In the following figure, since the effective time window of Stop 2 is entirely after Stop 1 time window, Stop 2 cannot appear before Stop 1 in any stop sequence.

2. Insufficient overlap:

In the following case, though there is an overlap in the time windows, this overlap time may not be sufficient to cover the drive time from Stop 2 to Stop 1 and the activity times at the stops. So again in this situation, Stop 2 cannot precede Stop 1 in a stop sequence.

 

3. Sufficient overlap, but high non-overlap:

In the above example, there can be just sufficient overlap in the effective time windows of two stops, but if the time window of Stop 1 starts considerably earlier than that of Stop 2, and/or the time window of Stop 2 ends considerably later than that of Stop 1, it will be beneficial to always sequence Stop 1 earlier than Stop 2. However this decision is optional and is controlled through the logic configuration multistop parameter EXTRA TIME WINDOW OVERLAP BETWEEN STOPS.

For example, suppose effective time windows of Stop 1 and Stop 2 are 8 AM - 12 PM and 11 AM - 6 PM respectively. So, the time overlap is 1 hour. Suppose the total of the drive time from Stop 2 to Stop 1 and the activity times at the stops is 45 minutes. So the minimum time overlap required in this Stop 2 - Stop 1 case is 45 minutes. Therefore there is a chance to get from Stop 2 to Stop 1 before it is too late. However, when EXTRA TIME WINDOW OVERLAP BETWEEN STOPS = 30 minutes, OTM will make the minimum time overlap required in this case 45 + 30 = 1 hour 15 minutes. So, even though there is a chance to get to Stop 1, OTM eliminates that possibility through this parameter setting. This approach is effective in generating more practical and time-feasible sequences.

It is not recommended to set this parameter to a very high value since it could eliminate a large number of good sequences.