In 1924 the company received a concession from the ministry of transport to build a private railroad from Warsaw through Grodzisk Mazowiecki to Żyrardów, under the condition that it would be run at least 2 kilometers from the existing line of the former Warsaw-Vienna Railway owned by the Polish State Railways (PKP). The work began in Komorów and proceeded simultaneously in two directions. In 1927 a 32.4 kilometers long standard gauge line electrified at 650 V DC with overhead wire was opened, linking Grodzisk Mazowiecki with the center of Warsaw. The line was connected with a 3 kilometer long non-electrified technical line with national rail system in Komorów, 24 kilometers of the line between Podkowa Leśna and Warsaw consisted of double track, the four kilometers long segment of the line leading to railroads final station in Warsaw at Marszałkowska Street was embedded in the city streets. The railroad operated 20 four-axle electric railcars produced by the English Electric Company at Preston, capable of traveling with a speed of up to 70 km/h, along with 20 unpowered passenger cars.