bogies (trucks) and propulsion systems (see Rolling stock, below, for more details). The section between Tasqueña and Estadio Azteca (Aztec Stadium), just short of Huipulco junction (for the branch to Tlalpan), opened as light rail on 1 August 1986, but ran for only three days before poor reliability with the heavily rebuilt rail cars led to a decision to suspend service. Service resumed in November 1986. Right-of-way work then shifted to the line's outer section, between Estadio Azteca and Xochimilco, with similar upgrading for higher-speed operation. This section opened on 29 November 1988. The old tram line 54 had included a long loop through the historic centre of Xochimilco, along narrow city streets, but this was not included in the upgrading to light rail, and was permanently abandoned when closed in 1984. The branch from Huipulco junction to Tlalpan was also rebuilt, but in a different manner, changed from private right-of-way to street running (without separation from other traffic) in the middle lanes of Calle Ferrocarril (now known as Renato Leduc) and also shortened by about at its outer end, no longer reaching Avenida San Fernando. Three high-platform stops were built, one being at the new terminus, which was referred to simply as "Tlalpan" on the rail cars' destination signs. Service to Tlalpan was reintroduced on 13 March 1990, now running only as a one-car shuttle to and from Estadio Azteca, no longer through to Tasqueña. Patronage was low, and service was discontinued only one year later, in March 1991, after an accident damaged the one car (No. 000) normally assigned to the Tlalpan route. Service was reinstated on 13 December 1991, as STE began to place new cars into service on the Xochimilco line, but ceased again on 6 October 1992 and has never resumed. The overhead line voltage was 600 volts DC until around the end of 1995, when it was raised to 750 V. Route The line runs between Metro Tasqueña and the town of Xochimilco, south of Mexico City. It serves the Coyoacán, Tlalpan, and Xochimilco boroughs, giving residents a fast link to the urban south of Mexico City. For the northern stretch of its run, it travels along the central reservation of the Calzada de Tlalpan, as does Metro Line 2 south of Metro San Antonio Abad – for this reason, it is sometimes seen as a continuation of that line, albeit on a more