[9][10] With the subsequent Mexico City tramway closures that took effect in May 1979, the only tramlines left in operation were routes 53 and 54, running from Tasqueña metro station to Tlalpan and Xochimilco, respectively.

The separation from street traffic, except at crossings, made routes 53 and 54 more like what later came to be called light rail unlike Mexico City's other tramlines which were closed by 1979, but these lines still lacked other light-rail attributes such a full stations.

[10][13] The 5.5-kilometre (3.4 mi) 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.

[13] Right-of-way work then shifted to the line's outer section, between Estadio Azteca and Xochimilco, with similar upgrading for higher-speed operation.

[10] The 1.7-kilometre (1.1 mi) 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 125 metres (410 ft) 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.

It serves the Coyoacán, Tlalpan, and Xochimilco boroughs, giving residents a fast link to the urban south of Mexico City.

[16] The Xochimilco line's rolling stock currently consists of 24[2] articulated light rail vehicles (LRVs) built by Concarril or Bombardier/Siemens, between 1990 and 2014.

The Moyada cars had all-new bodies and were equipped with pantographs instead of trolley poles to collect current from the overhead wires.

One half of each two-section LRV was scrapped, and in 2013 STE hired Bombardier to supply two all-new half-car sections and to combine them with the undamaged halves of the two LRVs.

[2] They were delivered in summer 2014 and entered service on 16 March 2015,[3] increasing the size of the fleet to 24 cars (numbered 017–040).