The planning of the S-Bahn and the Rail 2000 long-haul project raised the idea of building the Weinberg Tunnel, a through route from Zürich Hauptbahnhof to Oerlikon. That proposal was initially postponed, but the great success of the S-Bahn led to an expansion of services and, consequently, to capacity constraints. Plans were made to expand existing rail lines within Zürich leading to the north, but this encountered resistance from the population living near those rail lines.