Since August 1987, the Mexico City Metro (People's Rapid Transportation System) has a new route in service. This is Line No. 9, whose eastern part runs 9 m (29.5 ft) above ground level. Mexico City Metro is now 153 km (95 miles) long. Since 1969, when the facility first started operating, it has become one of the most economic, fastest and pollution-free transportation systems in the world. Today, the facility transports 5 million people per day. Metro System comprises four different types of structural elements: tunnel, subway, street level and elevated structure.
