Geography Reference
In-Depth Information
Fig. 7.7
Joint activity participation on Saturday (meeting: P1, P2, P3, and P4)
The critical index concept of a link has been proposed to evaluate the use priority of
links in real taxi services. This definition helps to choose a feasible and comfortable
space-time path for scheduling joint activity participation. In addition, the concept
of the utility index of an opportunity has been presented to evaluate the use of
critical links while choosing an available opportunity in the prism. A high index
value means that the opportunity has a higher probability of using the popular paths
of taxi drivers. These two concepts can facilitate activity scheduling services using
a feasible mechanism of incorporating taxi drivers' choices of travel paths.
With the help of the extended TVNBP, the critical links and opportunities were
identified in two steps. The first step is to find all available activity opportunities
between origins and destinations within the extended TVNBP. The second step is
to filter these available activity opportunities by analyzing a number of alternative
space-time paths to find the shortest space-time path for the opportunity connecting
an origin and a destination with optimal values of the link critical index and the
utility index of opportunities.
The joint activity participation scheduling problem was modeled as a multi-
objective optimization problem. Five objectives were used in this problem: (i)
minimizing travel distance; (ii) minimizing travel time; (iii) maximizing expected
participation activity time; (iv) minimizing the added travel time over alternative
space-time paths; and (v) maximizing the utility index of the selected critical activity
opportunity. The problem was solved by modifying the NSGA-II algorithm to limit
the search space to focus only on critical links and available activity opportunities in
the extended TVNBP. In this way, the joint activity participation scheduling problem
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