Shift Work Optimization
Problem description
Shift scheduling or employee work scheduling, is an integral part of any business that operates on shift work. Effective scheduling helps businesses reduce labor costs, boost staff morale, improve efficiency, and much more. Typically, the schedules will have constraints, such as "no employee should work two shifts in a row". Finding a schedule that satisfies all constraints can be computationally difficult.
Below we describe two examples of such work:
Crew scheduling
Most transportation systems use software to manage the crew scheduling process. Crew scheduling becomes more and more complex as you add variables to the problem. These variables can be location, skill requirement, shift of work and set roster of people. In the Transportation industries, such as Rail or mainly Air Travel, these variables become very complex. In Air Travel for instance, there are numerous rules or "constraints" that are introduced. These mainly deal with legalities relating to work shifts and time, and a crew members qualifications for working on a particular aircraft. Add numerous locations to the equation and Collective Bargaining and Federal labor laws and these become new considerations for the problem solving method. Fuel is also a major consideration as aircraft and other vehicles require a lot of costly fuel to operate. Finding the most efficient route and staffing it with properly qualified personnel is a critical financial consideration. The same applies to rail travel.
Nurse Scheduling problem
The Nurse Scheduling problem (NSP) consists of generating a schedule of working and rest days for nurses working in hospital units. The schedule should determine the shift assignments of nurses for a predetermined window of time, and must satisfy requirements imposed by the Rules of Procedure of hospitals. A proper solution to the NSP is crucial to guarantee the high level of quality of health care, to improve the degree of satisfaction of nurses and the recruitment of qualified personnel.
Constraints
Many variations of the problem exist, including the following:
- Working group needs specific skills and positions (like leader, supervisor, ...)
- Person has specific skills and working position
- Every shift team member has (at least) two shifts off after an attended shift
- Working group needs specific tools or instruments
- Absence prevents arranging to certain shift
- A shift must have a group in team of exactly number of persons (or less, defined by size)
- Person has the amount to be paid by the hour
- Groups can be formed without certain skills, but get penalties
The formulation is defined as a specific set of soft constraints together with the weights associated with each of them. The SWO problem is formulated as a combinatorial optimization problem whose objective function is to minimize the weighted sum of penalty points and cost.
Example
Example above: 20 persons, 15 shifts, 2 groups (when necessary). Cost, necessary skills and interpersonal relationship optimization
Add-ons
In addition we can consider of certain additional constraints:
- Psychological profile of employee
- Like or dislike coworker
- Optimization process can be combined with Job Shop Scheduling (Read more)