LegalFarePlan: A Label-Setting Framework for Fare-Transparent Urban Rail Route Planning under Non-Additive Fare Rules

LegalFarePlan is a route-planning framework for urban rail systems whose fare for one paid journey may differ from the sum of fares across legally separated journey legs. It explicitly models exit-and-reentry operations, including station costs, transfer rules, an extra-time budget, and a split limit. The artifact provides Dijkstra shortest-time and direct-route baselines, a greedy heuristic, bounded exact label-setting, and Pareto-frontier search. On a 57-station semi-synthetic benchmark covering 360 origin-destination pairs, bounded exact search found positive modeled fare reductions for 71.11% of pairs, averaging 3.78 and reaching 9.0 synthetic fare units under a 45-minute extra-time budget.