During the normalisation era, the government decided to buy Soviet Ečs cars instead of Czech R1s. The Ečs cars from the Mytishchi engineering plant were much heavier, which entailed a number of complications, especially concerning the structural soundness of Nusle Bridge. The Ečs cars were at the end of their service life, they did not have the required performance and no modernisation was possible. Later, the most widespread carriages in the Prague metro were the upgraded 81-71, but in the early 1990s it was evident that the metro fleet was becoming obsolete. Škoda Plzeň therefore started to significantly modernise the cars. They have been running on lines A and B since 1996. The first domestically developed metro trains were the M1s, which have been carrying passengers on the C line since 2000.