Adding carriages is not an isolated rolling-stock decision. Longer trains require longer platforms and points before passengers can board and trains can move through the network efficiently. Double-deck vehicles likewise depend on bridge and structure clearances rather than the carriage design alone. Adding tracks to an Australian main line would also require the route and its connected infrastructure to be relaid or changed as a system. Crowded trains and sparse transcontinental track both show why an upgrade must fit the network around it.
Notable Point · 42:50-43:38
Rail capacity rises only when the whole system fits
Longer or double-deck trains require points, platforms, bridges, and loading arrangements to be upgraded as one compatible network.