Workforce scheduling and routing problems: literature survey and computational study
Summary (2 min read)
- 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.
- 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....
...…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....
"Workforce scheduling and routing pr..." refers background or methods in this paper
...Such instances are the ones by Solomon (1987) and Castro-Gutierrez et al (2011), which represent a total of 183 instances for these initial experiments....
...The prefixes used to identify each of the data sets are as follows: Sol refers 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…...
...There are a few benchmark data sets for the VRPTW, here we refer to the ones by Solomon (1987) and Castro-Gutierrez et al (2011) which we adapt for our computational experiments....
...Solomon (1987) VRPTW data set has been used broadly in the literature....
...We consider here the following data sets from the literature: (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…...
"Workforce scheduling and routing pr..." refers methods in this paper
...Then, local heuristics based on destroy and repair moves are used to improve the solutions (Ropke and Pisinger, 2006)....
"Workforce scheduling and routing pr..." refers background in this paper
...Many types of personnel scheduling problems have been tackled in the literature (Baker, 1976; Miller, 1976; Golembiewski and Proehl Jr, 1978; Cheang et al, 2003; Ernst et al, 2004; Alfares, 2004)....
"Workforce scheduling and routing pr..." refers background in this paper
...If the vehicle arrives before the time window, it must wait until the time window opens to perform the delivery (Desrochers et al, 1992; Kallehauge et al, 2005)....
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Frequently Asked Questions (2)
Q1. What contributions have the authors mentioned in the paper "Workforce scheduling and routing problems literature survey and computational study" ?
The authors refer to these scenarios as Workforce Scheduling and Routing Problems ( WSRP ) as they usually involve the scheduling of personnel combined with some form of routing in order to ensure that employees arrive on time at the locations where tasks need to be performed. The first part of this paper presents a survey which attempts to identify the common features of WSRP scenarios and the solution methods applied when tackling these problems. The second part of the paper presents a study on the computational difficulty of solving these type of problems. The computational study provides an insight into the structure of the adapted test instances, an insight into the effect that problem features have when solving the instances using mathematical programming, and some benchmark computation times using the Gurobi solver running on a standard personal computer.
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.