A comprehensive analysis of duplication in public transportation

Route duplication is a condition in public transportation networks where multiple transit routes overlap. This occurrence can have positive effects, such as increased coverage and reliability, and negative effects, including higher operating expenses and increased network complexity. While the literature provides definitions of duplication and uses duplication indicators to analyze transit system performance, a comprehensive definition of the duplication concept is still lacking. This study addresses this gap by proposing two perspectives on duplication: route segment duplication and passenger connection duplication. We consider service frequency, the rolling stock, and the vehicle type (size and capacity) to derive the level of duplication. We also determine the subject of duplication based on two unique characteristics: trajectory (road segments and stops) and schedule (service frequency or trips). These characteristics are combined in the route variant or Line-Alternative-Direction (LAD), making LAD the subject of duplication. Our analysis indicates that the level of duplication using the proposed approach is significantly lower than that measured using traditional methods. Moreover, evaluating duplication from the service frequency perspective allows for an assessment of competitiveness among different route segments operated by various providers. A real-world case study in Almaty, Kazakhstan demonstrates the applicability of the proposed methodology to a complex urban transit network. Based on the findings, we propose policy recommendations such as shortening underutilized route segments and reallocating resources toward exclusive or high-demand links to enhance operational efficiency and service reliability.