Deep below Jakarta's traffic-choked streets, engineers and others are hard at work in a warren of transit tunnels - which could prove the key to easing the crippling gridlock in the capital city of South-east Asia's biggest economy. Construction of the 17 trillion rupiah (S$1.6 billion) first phase of the Mass Rapid Transit (MRT) system is expected to be completed in December, JakartaGlobe.id reported in March. The 15.7km stretch connecting Lebak Bulus in South Jakarta with the Hotel Indonesia traffic circle in Central Jakarta is scheduled to start operations in March next year, officials have said, providing some respite to the city's 10 million inhabitants, who endure hours-long commutes every day. The city is to eventually have a 112km MRT system with more than 60 stations by 2025. The system will be integrated with other transportation networks, such as the 42km first phase of a light rail transit system, JakartaGlobe said.