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 [REF].
Starting in November 1997,[REF] and lasting for four years, STE operated a few diesel bus routes, at the request of STV following the 1995 bankruptcy[REF] of RTP's predecessor, Ruta Cien ("Route 100") [REF].