World metro lines currently under construction. Active tunnelling, new subway station builds and rapid transit line extension projects.
World metro and subway lines currently under active construction: new lines being tunnelled through city centres, extensions pushing into new suburban areas and second phases of recently opened routes. Metro construction is among the most complex and expensive of all rail infrastructure projects, requiring deep-bore tunnelling, major excavations and years-long surface disruption. The map shows where urban rapid transit investment is currently taking place.