Kolej Dojazowa in 1939 carried 4000 passengers a day and ran trains every 10 minutes during rush hours. Its core business had not yet reached profitability, however the company made money reselling real estate which gained in value significantly due to the railroad. During World War II the railroad remained operational during most of the German occupation albeit only on part of the line. In 1947 the company was nationalised by the Soviet installed communist government and in 1951 placed under the administration of the Polish State Railways and renamed to Warszawska Kolej Dojazdowa (Warsaw Commuter Rail), however the line retains a narrower loading gauge and (until 2016) its specific electrification system while the national rail network uses 3 kV DC. During the 1960s the line was gradually trimmed at its ends and in Warsaw moved to newly built tracks in a cutting of the western part of the Warsaw Cross-City Line. In 1972 the almost half-a-century-old English Electric railcars were replaced by new PKP class EN94 EMUs produced by Pafawag in Wrocław designed especially for the line. In 2001 with the restructuring of the Polish State Railways a separate company called PKP Warszawska Kolej Dojazdowa Sp. z o.o. was created within the PKP Group and in 2007 taken over by a consortium formed by the Masovian Voivodeship and the municipalities through which the line runs, dropping the letters PKP from its name. Several proposals have been made for the modernisation of line, proposing alternately either switching the line to standard tram rolling stock and eventually integrating with the Warsaw Tramway system or rebuilding the line to standard rail loading gauge and converting to a 3 kV electrification system in order to integrate it with the national rail network. Additionally, plans have been prepared for moving the final station of the line in Warsaw to Rondo Dmowskiego at Marszałkowska Street in order to facilitate easier transfers to the Centrum station on line M1 of the Warsaw Metro and to build the second, long-planned line between Komorów and Nadarzyn, however as of 2022 no funds have been allocated towards any of those. In 2004 Warszawska Kolej Dojazdowa received a single prototype of a new EMU designated PKP class EN95 built by PESA in Bydgoszcz which remains in service today, however no further units of this type have been ordered. Instead in 2010, the company ordered also from PESA 14 EMUs class