MUMBAI (AFP) –
India's first "sea bridge" was officially opened in Mumbai on Tuesday, raising hopes that the state-of-the-art structure will ease chronic congestion on the city's notoriously choked roads.

The sweeping, 5.6-kilometre (3.5-mile) Bandra-Worli Sea Link was inaugurated by the ruling Congress party chief Sonia Gandhi on a visit to India's financial capital.

It is hoped that the 16.5-billion-rupee (340-million-dollar) eight-lane freeway will help cut the 40-minute journey between the suburbs of Bandra and Worli to just eight minutes.

But although hailed as a triumph of engineering, the landmark bridge -- seen as a beacon of hope for other, much-needed infrastructure projects elsewhere in India -- is not fully operational.

Only four lanes will be open to traffic from 12:01 am Wednesday. Work is scheduled to be completed on the remaining section in the coming months.