Workforce scheduling and routing problems: literature survey and computational study
Summary (2 min read)
1 Introduction
- In recent times, employees often need to be more flexible regarding the type of jobs they perform and similarly, employers need to make compromises in order to 1 Moreover, in some cases workforce should perform tasks at different locations, e.g. nurses visiting patients at their home, and technicians carrying out repairs at different companies, etc.
- The authors are interested in those workforce scheduling problems in which personnel is considered flexible (in terms of tasks and working times) and mobile (travelling is required in order to do the job).
- In each subsection of Section 4 the authors also review the different solution techniques (optimisation, heuristics and hybrid approaches) that have been used to tackle these problems.
2 Workforce Scheduling and Routing Problems
- 1 Description of the Problem Workforce Scheduling and Routing Problem (WSRP) refers to those scenarios involving the mobilisation of personnel in order to perform work related activities at different locations.
- The number of activities varies depend- ing on the duration of the working shift, but assuming that each activity needs to be performed at a different location, a routing problem also arises.
- The authors include the characteristics that appear the most in the literature.
- Matching employees’ skills to the tasks assigned has been tackled for complex organisations (Cordeau et al, 2010).
- A maximum difference dependency establishes a limit for the start on the second activity from the end of the first activity.
3 Vehicle Routing Problem with Time Windows
- The routing part in many of the problems considered here as examples of WSRP is based on the vehicle routing problem with time windows .
- The delivery vehicle must arrive at the location within that specified time window.
- Extensions of the VRPTW include other features such as multiple trips, multiple depots and synchronisation of vehicles.
- This applies to the case when employees could perform more than one trip on a day to visit the same location.
- Other researchers use hybrid methods that employ heuristics for the generation of columns within a column generation setting (Bredström and Rönnqvist, 2008) or use heuristics to improve an initial solution found with mathematical programming (Fischetti et al, 2004).
4 Workforce Scheduling and Routing Problems in the Literature
- In this section the authors review some of the problems tackled in the literature that can be considered as a type of workforce scheduling and routing problem (WSRP).
- Additionally, nurses have time limitations on the number of working hours per day or the starting and ending time.
- Additional features of home care include prioritising visits.
- Other methods include hyperheuristics Misir et al (2010).
- Some telecommunication companies require scheduling employees to perform a series of installation and maintenance jobs, e.g. Cordeau et al (2010).
5 Computational Study
- As the above survey reveals, workforce scheduling and routing problems (WSRP) arise in a variety of scenarios.
- Figure 1 gives an insight into the performance of the solver in one of instances of size 25 for which the optimal solution was found.
- Instances in the considered data sets have a range of time window sizes.
- Then on average, activities in the Mov, Sec and Sol instances require more than 1 employee and this is illustrated in Figure 11.
- In the procedure to generate connected activities the authors needed to consider the already given time windows for each activity.
6 Conclusion
- A workforce scheduling and routing problem (WSRP) refers to any environment in which a skilled diverse workforce should be scheduled to perform a series of activities distributed over geographically different locations.
- The problems identified include but are not limited to: home health care, home care, scheduling of technicians, security personnel routing and rostering, and manpower allocation.
- The survey part of this paper also sought to identify the solution methods that have been employed in the literature when tackling WSRP scenarios.
- The authors acknowledge the authors (Castro-Gutierrez et al, 2011; Rasmussen et al, 2012; Misir et al, 2011; Günther and Nissen, 2012) who kindly provided us the original data sets to perform this study.
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Cites background from "Workforce scheduling and routing pr..."
...In addition, Castillo-Salazar et al. (2014) presented a survey on routing and scheduling problems that summarises the key characteristics of the problems as well as the corresponding solution methodologies developed and applied to realistic problem settings....
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...…constrained problems is broader since it covers all possible types of resources, including vehicles, machinery, specialised equipment and anything that can enable the delivery of service and products to the customers, i.e., not only skilled personnel as in the Castillo-Salazar et al. (2014) survey....
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References
379 citations
"Workforce scheduling and routing pr..." refers background in this paper
...Such models have been tackled using constraint programming, branch and bound, and branch and price (column generation) (Barnhart et al, 1998; Desrosiers and Lübbecke, 2005)....
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...Such models have been tackled using constraint programming, branch and bound, and branch and price (column generation) (Barnhart et al, 1998; Desrosiers and Lübbecke, 2005)....
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351 citations
"Workforce scheduling and routing pr..." refers background or methods in this paper
...…homes to administer medication or provide treatment (Cheng and Rich, 1998), care workers aiding members of the community to perform difficult tasks (Eveborn et al, 2006), technicians carrying out repairs and installations (Cordeau et al, 2010), and security guards performing night rounds on…...
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...Finally, the combination of a set partitioning model and a repeated matching algorithm, to find suitable pairs of employees and routes in a hybrid approach has also been used to tackle Home Care (Eveborn et al, 2006, 2009)....
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...4.2 Home Care The home care problem also called domiciliary care, refers to the provision of community care service by local authorities to their constituents (Akjiratikarl et al, 2007)....
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...Start and End Locations can be from one location, where all employees start at the main office (Eveborn et al, 2006), up to many locations (perhaps as many as the number of employees) assuming each employee may start from their home....
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344 citations
"Workforce scheduling and routing pr..." refers background or methods in this paper
...We then use the MIP model by Rasmussen et al (2012) to tackle all the adapted instances from the 5 data sets....
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...…(1) VRPTW instances by Solomon (1987), (2) multi-objective VRPTW instances by CastroGutierrez et al (2011), (3) home health care instances by Rasmussen et al (2012), (4) security personnel scheduling instances by Misir et al (2011) and (5) field technicians scheduling instances by Günther…...
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...…to the 168 instances from Solomon (1987), Mov refers to the 15 instances from Castro-Gutierrez et al (2011), HHC refers to the 11 instances from Rasmussen et al (2012), Sec refers to the 180 instances from Misir et al (2011) and Tech refers to the single instance from Günther and Nissen…...
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...Such dependencies, although present in the real world, are not incorporated in most instances from the literature with the exception of those by Rasmussen et al (2012)....
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...We set the weights in the objective function to the same values suggested by Rasmussen et al (2012)....
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314 citations
"Workforce scheduling and routing pr..." refers background or methods in this paper
...4.1 Home Health Care Bertels and Fahle (2006) describe home health care (HHC) as visiting and nursing patients at their home....
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...This problem is related to the home health care problem described earlier (Bertels and Fahle, 2006; Cheng and Rich, 1998)....
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...Another example of combining two approaches is when using constraint programming to obtain a good feasible solution and in a second stage applying a series of meta-heuristics including simulated annealing and tabu search (among others) to improve the quality of the solution (Bertels and Fahle, 2006)....
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...…example of combining two approaches is when using constraint programming to obtain a good feasible solution and in a second stage applying a series of meta-heuristics including simulated annealing and tabu search (among others) to improve the quality of the solution (Bertels and Fahle, 2006)....
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302 citations
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Frequently Asked Questions (2)
Q2. What have the authors stated for future works in "Workforce scheduling and routing problems literature survey and computational study" ?
The authors consider some extensions for future work. Secondly, to apply a different MIP model or extend the one by Rasmussen et al ( 2012 ), seeking to include other features such as: employees capacity ( number of hours allowed to work within the time horizon ), employees breaks, and balancing the number of activities in routes.