Hello, I'm a french fan and I wanted to propose an hybrid suburbancommuter/rapid transit line located in France, the RER A or Regional Express Network line A or Ligne A du Réseau Express Régional It's the densest european line and one of the densest line in the world she have 46 stations and 5 branchs with one central noun here is the Wikipedia article : https://en.wikipedia.org/wiki/RER_A Tracks : 108.5 kilometers or 67.4 miles 5 branchs Cergy-le-Haut Poissy Boissy-Saint-Léger Marne-la-vallée-Chessy ( Disneyland Paris) Tracks gauge : 1.435 mm Operation: Opérator : SNCF / RATP Rolling stocks : MS 61 MI 84 (Wikipedia is not available in english) MI 2N(Altéo) MI 09 Signals : French Signalisation + Traffic control system developed by siemens ("SACEM") in english "Driver Assistance, Operation, and Maintenance System" Since summer 2018 the MI 2N and the MI 09 can use an "Automatic Train Operation" (ATO) mode this is the end of the post thank you for reading me Sorry for the bad english
it will be a good idea because it's one of or the most used line in France. We can't say it's not popular and will be a good idea to start in France because it's Paris and cities around.