More recently, Mourão et al. [53] study the sectoring arc
routing problem, which has a natural application in waste collection.
The aim is to partition the service territory into a number of
sectors, so that each sector can be covered by a set of vehicle trips.
G. Ghiani et al. / Computers & Operations Research 44 (2014) 22–32 29
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The authors propose three heuristics to face this problem. The first
two heuristics are made up of two phases. In the first phase the
sectors are determined, whereas in the second phase vehicle
routes are obtained by solving a mixed capacitated arc routing
problem (MCARP). The two variants differ by the heuristic used for
the sectoring phase. In particular, the first sectoring heuristic,
called Circuit of Tasks Heuristic, adds to the selected sector the
tasks of a small demand circuit computed in a balanced graph.
On the other hand, the second sector heuristic, Single Task Heuristic,
adds one task at a time. Finally, the third heuristic, namely the
Best Insertion Heuristic, builds sectors and trips simultaneously.
In particular, each sector is initialized with a different seed-task,
and, in order to ensure that the different sectors are balanced, at
each iteration it is chosen to expand the sector with the least
workload. Then, to limit the increase in workload and to keep the
sectors as compact as possible, one task close to such a sector is
added to it. The three heuristics are tested on three groups with
five MCARP instances each, resembling waste collection operations
in modern towns, old historical town centers, and low-traffic
suburban areas.