Metro Line M3 (Budapest Metro)

Mayor of Budapest Gábor Demszky was warned in 2006[6] by BKV that the line would soon need reconstruction, but no steps towards this were made before the new mayor István Tarlós took office in 2010. The trains started burning or smoking multiple times, but this has caused neither fatalities nor serious injuries as of yet. Tarlós reacted by ordering the retirement of all trains that were more than 40 years old. He also started the reconstruction of the tracks, because they were also reported as hazardous. In 2014 the mayor's administration finished laying out the plans for the complete reconstruction of the line and Viktor Orbán's government allowed the local government to finance the reconstruction of the trains by taking up loans. Repayment of the loans was guaranteed by the national government in case the municipal government was not able to pay. The municipal government requested EU funds to finance the reconstruction of the underground infrastructure (tunnels and stations), the national government assured it would provide financing in case no or less EU funds were obtained than the necessary amount.

The first metro train was handed over in January 2016 to the Russian Metrowagonmash (the original manufacturer) to be reconstructed.[7] Tarlós had preferred buying new trains, but he had been overwritten by the Orbán-government.[8] The prototype of the reconstructed trains entered service on March 20, 2017.[9] Since then, the number of reconstructed trains serving the line is scheduled to increase by 2 trains every month.

On September 4, 2017 the contracts for reconstructing the whole tunnel and the stations of the northern section were signed, thus effectively starting the reconstruction. The stations were to be finished by December 31, 2018, but eventually they were only opened on March 30, 2019. The reconstruction of the southern section (Népliget – Kőbánya–Kispest) was started on April 6, 2019. The plan is to upgrade the metro at Arany János utca and Ferenciek tere from 9 March 2020,[10] and from July 2020 at the metro stations of the Corvin Negyed and Semmelweis Klinikák. Reconstruction between the Nyugati Pályaudvar and Semmelweis klinikák will begin after the southern section has been commissioned. At these stops, the underground trains pass without interruption during work in the passenger compartment. Overhauling the tunnel is set to be completed by August 24, 2020. After this reconstruction, the renewed train will more likely stay in service for more than 20 years before they going to have to be replaced.[11]

Civil groups voiced their concerns over the lack of accessibility and air-conditioning.[12] In response, Tarlós promised modular AC units would be installed on the trains and the government agreed to make 18 out of the 20 stations accessible.[13][14]