Metrovagonmash 81-717/81-714

The 81-717/714 is a Soviet/Russian electric multiple unit for rapid transit applications, designed in the Soviet Union in the mid-1970s. The cars were made from 1976 to 2021 by Metrovagonmash and the I. E. Yegorov Vagonmash factories of Mytishchi and Saint Petersburg, respectively, though production is still ongoing for specific modifications. The 81-series trains are the most widespread metro train ever, being produced in 24 different variations currently being used in 19 rapid transit systems across 11 countries, as well as being the metro train with the longest production span and largest total production number, with over 7000 cars having been manufactured in total so far.

The names 81-717 and 81-714, also known as Nomernoy in some countries, and as Vagonmash in other ones, come from the Soviet electric rail vehicle numbering system, where the 81-717 cars are the control cars and the 81-714 are the trailer cars. Unlike the previous metro trains made in the Soviet Union, they never received a lettered classification, thus, they have been known as the 81-series or the Numbered Trains (Номерной Поезд). The numbered trains, as they are known colloquially among railfans and some commuters, feature restyled front ends, stronger electric traction motors, complex and wider usage of various electronic devices, and are more advanced than their predecessor, the E-series.

They were first deployed in Moscow in 1978, and have since then seen widespread usage in the former USSR and its satellite states in Prague, Budapest, Warsaw, and Sofia.