90% will be underground (last item of the list of figures at beginning): https://www.societedugrandparis.fr/info/grand-paris-express-largest-transport-project-e

90% will be underground (last item of the list of figures at beginning): https://www.societedugrandparis.fr/info/grand-paris-express-largest-transport-project-europe-1061 https://www.societedugrandparis.fr/info/grand-paris-express-...