Abstract
Urban rail fare systems may be non-additive: the fare of a single paid journey from an origin to a destination can differ from the sum of fares over multiple legally separated journey legs. This paper presents LegalFarePlan, a fare-transparent route-planning framework that models legal exit-and-reentry operations as explicit, auditable constraints.
Methodology
The framework considers a transit network, fare function, transfer rules, station-level exit/re-entry costs, an extra-time budget, and a split limit to compute explainable route plans over paid journey segments. The implementation includes:
- Dijkstra shortest-time and direct route-planner baselines
- Greedy split heuristic
- Bounded exact label-setting
- Pareto-frontier search
Evaluation
Evaluation uses controlled synthetic data and a 57-station semi-synthetic benchmark with 360 OD pairs. On the semi-synthetic benchmark, bounded exact search identifies positive modeled fare reductions for 71.11% of OD pairs, with a mean reduction of 3.78 and a maximum reduction of 9.0 synthetic fare units under a 45-minute extra-time budget.
These results demonstrate method behavior and reproducibility; they are not empirical conclusions about MTR or any transit operator.
Blogger's Review: The LegalFarePlan framework introduces a novel approach to fare planning by transparently modeling legal exit-and-reentry operations. Its effectiveness in fare reduction highlights the potential for real-world applications, warranting further exploration of its adaptability across various transit networks.