Abstract : The Spidernet concept consists in making a metropolitan, heavy rail station the hub of a web of elevated guided ways dedicated to small-size cabins driven automatically. Thus, comfortable point-to-point transport service would be provided to passengers, offering both speed and reliability (since its running would be uninterrupted), together with quick access and short wait at egress station were there sufficiently many " podcars ". This specific concept of Personal Rapid Transit (PRT) is purported to empower the local attraction of the heavy network and to develop the hub potential as service centre and urban centre. The paper investigates these issues in the case of the St Denis station in the Grand Paris Express network by the time horizon of implementation. After introducing the territorial context and putting forward a tentative scheme of Spidernet dedicated ways and stations, we turn to simulation to study potential demand, multimodal effects, fare sensitivity and potential revenues, as well as capital and operational costs. Two models are used complementarily: first, a macroscopic, four-step Travel Demand Model at the regional level; then, PRTSim is used for microscopic traffic simulation of both passengers and podcars. Microsimulation is essential to infer realistic enough traffic conditions on the supply side (way capacity, fleet size) as well as on the demand side (effective quality of service, wait time at access station, opportunity of car-sharing). The tentative estimation of revenues and costs suggests that financial profitability might be achieved. Yet a number of important topics still deserve further investigation.