Servicio de Transportes Eléctricos

After May 1979, the only streetcar line still in operation was that from Tasqueña metro station to Xochimilco (route 54) and its short branch to Tlalpan (53).[13] STE upgraded this line in the mid-1980s as light rail, with high-platform stations for faster loading and new articulated light rail cars built using parts from old PCC streetcars, fitted with new bodies.[14] The Xochimilco Light Rail service began operating in 1986, without the Tlalpan branch. It continues in operation today, with newer cars, and locally is known as the Tren Ligero. It is STE's only rail line.[6] Construction of a new streetcar line (or tranvía) in the city center was planned,[15] with STE managing the construction bidding process for the project,[16] but on 31 May 2010 the project was cancelled by mayor Marcelo Ebrard, on cost grounds.[17]

An STE trolleybus at Tasqueña in 1990

After its opening in the 1950s the trolleybus network was gradually expanded. A network of 27 routes in operation in early 1979 was reduced to about 10 later that year, through a reorganization that combined overlapping routes, rather than through abandonments.[11] An expansion program implemented after 1982 raised the number of separate routes back to 27, operated by 30 different services,[8] by the end of 1988.[18] STE's network reached its widest geographic coverage at that point, when the route most-distant from the city center was one from Tláhuac to Milpa Alta, in the far southeastern corner of the Federal District.[18] This coverage was maintained only until early 1991. Although new routes were opened in 1995, 1997 and 2005, overall STE has, since 1991, discontinued more trolleybus routes than it has opened, with only 17 trolleybus routes still in operation in 2007.[4] In 2009 and 2010, construction work on new metro line 12 disrupted surface streets (requiring traffic detours) and caused some STE routes to be replaced by diesel bus routes, which were operated by RTP, as STE does not own any diesel buses. These conversions were originally planned be temporary, but whereas metro line 12 opened in October 2012, only one of the affected routes (D) had returned to operation by mid-2014, and a total of only eight trolleybus routes were in operation at that time,[2] a situation that remains unchanged in 2018.[1] The total number of trolleybuses scheduled in peak service each weekday is 264, as of mid-2014, from a fleet of around 360 serviceable vehicles.[2]

The trolleybuses serving the "Zero-Emissions Corridors" wear a two-tone-green paint scheme, but the distinctive graphic of El Ángel that was originally included (2009) was removed around early 2013.[19]

A trolleybus using a trolleybus-only contraflow lane on Eje Central

On 1 August 2009, STE inaugurated its first Corredor Cero Emisiones, or Zero-Emissions Corridor, in which all public transport service along one of the city's major traffic arteries is now provided by electric trolleybuses.[8][20][21] This was not a new trolleybus line, but rather an upgrading of an existing line, STE's route A, along Eje Central (Central Traffic Axis, primarily Avenida Lázaro Cárdenas).[20] The route extends for 18.3 kilometres (11.4 mi), from Instituto del Petróleo metro station and the Terminal de Autobuses del Norte (northern intercity bus station) to Tasqueña metro station and the Terminal de Autobuses del Sur (southern intercity bus station).[22] The changes involved in transforming route A into the "Zero-Emissions Corridor" included significantly increasing the frequency of trolleybus service, to an average headway of 2.5 minutes, and banning all non-electric buses and peseros (vans/jitneys) from the corridor.[20][21] The Eje Central corridor alone now uses about 90–100 trolleybuses at peak times, from a sub-fleet of 120 vehicles reserved for this route.[20] The trolleybuses operate in bus-only lanes, separated from other traffic; such lanes already were present on this route. Several of STE's other trolleybus routes also operate in bus-only lanes over some portions of their route.

Changes to route S (Eje 2/2A Sur) to transform it into a second Zero-Emissions Corridor took place in 2010, and the improved service was put into effect on 21 December 2010. Route S connects Chapultepec metro station with Velódromo metro station and is 9 kilometres (6 mi) long (18 km round trip).[23]

On 1 November 2012, the third Zero-Emissions Corridor was opened, along route D, from Mixcoac metro station to San Andrés Tetepilco, just past Calzada de Tlalpan, where it connects with metro line 2.[24] The terminus is located in front of STE's main trolleybus depot, which also houses a small museum preserving one of the first electric trams to run in the city, as well as PCC car 2784 and some other historic material and documents.[25]

The system has three trolleybus garages (depositos, or depots). The largest is at Tetepilco, also the location of STE's main administrative offices. The newest, El Rosario, opened in December 1998,[26] as a replacement for a much smaller depot, Azcapotzalco, which had closed in May of that year.[27] The third is San Juan de Aragón depot.[2] The trolleybus fleet included around 400 vehicles in 2008[4] and around 360 in 2014.[2]

Starting in November 1997,[28] and lasting for four years, STE operated a few diesel bus routes, at the request of STV following the 1995 bankruptcy[29] of RTP's predecessor, Ruta Cien ("Route 100").[30] It accepted the transfer of 190 motorbuses to its fleet in conjunction with this,[30] but these and the bus routes were transferred to RTP in November 2001.[31] Otherwise, except for a brief period in the 1960s, STE's service has always used only electric vehicles.[28]