JAKARTA, Indonesia: Indonesia’s long-awaited first subway opened Sunday in the country’s capital with the aim of relieving crippling traffic gridlock in Southeast Asia’s biggest economy.

Minutes after inaugurating the 16-kilometer (10-mile) transit line running south from Jakarta’s downtown, President Joko Widodo presided over a groundbreaking ceremony to mark the beginning of the second phase: Eight-kilometer (five-mile) northward line planned for completion by 2024. The two projects are being built at a cost of $2.6 billion.