Olympic volunteers take the metro line 4 in Rio de Janeiro, Brazil, on Aug 1, 2016. Rio's new metro Line 4 links the city's tourism district with the western Barra da Tijuca neighborhood, where many of the Olympic events are slated to take place. The key Olympic transport line features China-made trains designed and manufactured by the Changchun Railway Vehicles Co, a subsidiary of CRRC, one of China's biggest train makers. [Photo/Xinhua]