Renewal of rolling stock in a metro line: performance analysis and operational implications

In modern cities characterised by high population density, the mobility problem can be addressed by utilizing efficient public transportation systems. Shifting the demand from private cars to these systems can both increase the livability of a place and reduce negative environmental impacts. In this perspective, vehicles for urban rail and metro services should be periodically updated to meet the demand and replace obsolete rolling stock. However, the new rolling stock could have different performances compared to the old one and, in the case of such significant modernisation, an evaluation of the differences in performance between the old and the new configuration is necessary. Indeed, the modifications can bring benefits or disadvantages from a user or company cost perspective. In this work, a model is presented to compare the total cost, considering both energy costs and passenger travel costs, in the event of an update of the rolling stock. The model is then applied to Linea 1 of the Naples metro system (Italy) to evaluate the feasibility and usefulness of this approach.