A Mobility Equity Metric for Multi-Modal Intelligent Transportation Systems
Heeseung Bang, Aditya Dave, Filippos N. Tzortzoglou, Andreas A. Malikopoulos
TL;DR
The paper addresses equitable mobility in multi-modal intelligent transportation systems by introducing Mobility Equity Metric (MEM) and Mobility Index (MI), where MI at node $i$ is defined as $\varepsilon_i = \sum_{m\in\mathcal{M}} e^{-\kappa_i c_m} \cdot \left\{ \sum_{s\in\mathcal{S}} \beta^s \sigma_{i,m}^s(\tau_m) \right\}$. MEM uses a population-weighted Gini-based dispersion across origins to quantify how evenly MI is distributed, enabling cross-network comparisons. A control framework is developed where a system planner routes compliant public-transit vehicles to maximize MEM while accounting for non-compliant private vehicles via a cognitive-hierarchy model and a BPR latency function $t^{ij}(x^{ij}+q^{ij})=t^{ij}_0\left(1+0.15\left(\dfrac{x^{ij}+q^{ij}}{\gamma^{ij}}\right)^4\right)$. The planner optimizes mode weights $w_m$ under a constraint on travel-time disparity $\delta^{pv}(w)\leq\gamma$, and non-compliant drivers solve level-0 to level-2 shortest-time routing problems. Numerical simulations on a 16-node grid with 15 trips demonstrate how MEM, transit share, and compliance interact to affect network performance, illustrating the trade-offs between equity and efficiency in routing decisions. Overall, the framework provides a pathway to design MEM-aware routing in real-world multi-modal ITS, with implications for policy and planning under varying adoption and compliance scenarios.
Abstract
In this paper, we introduce a metric to evaluate the equity in mobility and a routing framework to enhance the metric within multi-modal intelligent transportation systems. The mobility equity metric (MEM) simultaneously accounts for service accessibility and transportation costs to quantify the equity and fairness in a transportation network. Finally, we develop a system planner integrated with MEM that aims to distribute travel demand for the transportation network, resulting in a socially optimal mobility system. Our framework results in a transportation network that is efficient in terms of travel time, improves accessibility, and ensures equity in transportation.