 However, the two-axled trailers did not give as smooth a ride, and in 1927 the company ordered bogie trailers from Atelier Métallurgique de Nivelles, which were put into service in 1928 and 1929.To allow more frequent services, the line needed to be rebuilt to double track.The first section was from Sportsplassen to Holtet, which opened with double track on 16 January 1930.