Planning cycles
•Strategic plans might cover the next four years and be updated annually;
•Aggregate plans might cover the next year and be updated every quarter;
•Master schedules may cover the next three months and be updated monthly.
•This pattern of repeated cycles actually makes planning a lot easier.
•Most operations are relatively stable, so the plans for one period can be used as the basis for plans in following periods.
Short-term Schedules
•Short-term schedules give detailed timetables for jobs, people, materials, equipment and all other resources.
•Short-term schedules give the sequences of activities, and the times when they should be done.
•The aim of these schedules is to organise the resources needed for the master schedule, giving low costs, high utilisations, or achieving some other measure of performance.
Approach to scheduling
•Backward scheduling, where schedulers know when a job has to be finished. Then they can work back through all the activities to find the date when the job must be started.
•Forward scheduling, where schedulers know when a job can start. Then they can work forward through all activities to find the date when the job will be finished.
Scheduling rules
The more complicated methods are usually too difficult and time-consuming for short-term schedules, and most organisations use simple methods, often based on scheduling rules:
•First come, first served
•Most urgent job first
•Shortest job first
•Earliest due date first
Example
•ZambrucciTransport has to schedule the following six jobs for a heavy lift crane.
•How can it design a reasonable schedule?