Automated Staff Scheduling Software Tim Curtois The OR Society Criminal Justice Special Interest Group 27 June 2012

Automated staff scheduling 2 Background  The software was originally developed as part of a PhD research project on automatic scheduling for healthcare personnel  The research was published and a demo put online  ASAP was approached by a software company interested in licensing the technology  The University of Nottingham formed a spin-out company to license the software engine

Automated staff scheduling 3 The Modelling Approach  During the research we collected data and benchmark instances from lots of different sources (e.g. industrial collaborators, other researchers)  Became clear that the problems varied significantly from one workplace to another not just in terms of problem size (e.g. staff numbers, planning horizon length, numbers and types of shifts) but also in the variety of working constraints and rules  Developed a model that would allow end-users to define custom rules and their priorities  Priorities are specified with weights/costs (number values). A penalty/cost is incurred when a rule cannot be satisfied  Objective is to minimise the sum of all penalties due to constraint violations

Automated staff scheduling 4 Example Constraints  Employee working constraints - Min/max hours worked, min/max consecutive days on or off, shift rotations, night shifts, weekends, shift requests etc  Cover/demand constraints - Min/max required employees during shifts/time periods (possibly skill/task based)  Ensuring employees work together (or do not work together)  Training/supervision, car-sharing, productivity based constraints  Similar skills, couple with children, or two employees just don't get on!

Automated staff scheduling 5 Problem Versions 1. Pre-defined shifts with fixed start and finish times (e.g. early shift, day shift, late shift, night shift) 2. Shift start and finish times not pre-defined, additional constraints e.g.  Earliest/latest shift start and finish times  Min/max shift lengths  Break lengths and times (often depending on shift lengths and start times)  Tasks assigned during shifts

Automated staff scheduling 6 Methodologies  Exact based (e.g. Branch and Price) Advantages  Works very well on smaller instances  Can provide optimal solutions or information on how close to optimal the solution is Disadvantages  On larger instances can require infeasible amounts of memory and computation times and so may not always return a solution  Heuristic based (e.g. Metaheuristics) Advantages  More robust and always returns a solution regardless of instance size and computation time Disadvantages  Outperformed by exact based methods on smaller instances  No information on how close to optimal the solution is

Automated staff scheduling 7 Demo  … (Software available at