Topology-Aware Gap Analysis for National DC Fast-Charging Networks: The Case of Türkiye

Abstract

This study evaluates the functional adequacy of DC fast-charging infrastructure using a network-based framework that moves beyond station counts to assess corridor continuity, traffic demand, and targeted expansion strategies. A graph representation of the national intercity highway system integrates public DC fast-charging stations as network seed nodes, and accessibility is quantified through multi-source shortest-path analysis. Minimum Viable Coverage (MVC) criterion and traffic-weighted metrics are used to reflect heterogeneous mobility demand across provinces. The results reveal pronounced spatial heterogeneity, highlighting a disconnect between nominal infrastructure availability and functional long-distance mobility. Inequality analysis shows that the top ten provinces account for approximately 72.8% of national traffic-weighted accessibility, while the bottom 40% contribute only about 2.2%. Sensitivity analysis across inter-charger distance thresholds indicates diminishing marginal gains beyond moderate spacing levels. A gap-based DC expansion scenario further demonstrates that a limited number of strategically placed stations can substantially restore consecutive coverage along previously disconnected highway corridors, yielding relative MVC improvements of up to 62% in structurally underserved provinces. At the national level, the targeted deployment raises primary-corridor MVC from 86.72% to 91.22%, recovering approximately 3,400 km of previously disconnected roadway. Overall, the proposed framework provides a transferable planning tool for improving corridor continuity, supporting targeted charging-infrastructure deployment, and informing the integration of growing EV charging demand into power-system investment decisions in emerging EV markets.