Venezuela is connected to the world primarily via air (Venezuela’s airports include the Simón Bolívar International Airport near Caracas and La Chinita International Airport near Maracaibo) and sea (with major seaports at La Guaira, Maracaibo and Puerto Cabello). In the south and east the Amazon rainforest region has limited cross-border transportation; in the west, there is a mountainous border of over 1,375 miles (2,213 km) shared with Colombia. The Orinoco River is navigable by oceangoing vessels up to 400 km inland, and connects the major industrial city of Ciudad Guayana to the Atlantic Ocean. Venezuela has a limited national railway system, which has no active rail connections to other countries; the government of Hugo Chávez invested substantially in expanding it. Several major cities have metro systems; the Caracas Metro has been operating since 1983. The Maracaibo Metro and Valencia Metro were opened more recently. Venezuela has a road network of around 100,000 km (placing it around 47th in the world); around a third of roads are paved. At one time Venezuela had the world’s highest cable car. The Mérida cable car opened in 1960, connecting Mérida with the top of the Sierra Nevada de Mérida. It was closed indefinitely in 2008, having reached the end of its service life.