Name case follows the usual colonial times.
Route network in 1893 Route network in 1918: (
Cape gauge), to narrow gauge), 1939: (Cape gauge), of which of track for first class top speed at . [9]
Operations The terrain is flat "Ostsumatras", structurally there was rarely climbs above 5 ‰ overwhelm. The Streckenbau nevertheless proved by the numerous rivers and swamps often difficult. Always provisions had to be made for the frequent floods in the monsoon and consequent damage to the tracks. The first tracks were laid in a bed of sand, soon was changed to gravel. The opening of the line Medan- Timbang Langkat () was 1 April 1886. It was soon to Salesseh extended. Later they were taken on, almost exactly in a southerly direction to a rubber plantation. The on July 25, 1886 provisionally inaugurated route went to the port Belawan near Medan (), but was initially only on a section to Labuhan Deli in operation since the construction of the bridge over the Sungei Deli proved difficult (New 1932), Next, they took the branch line from Medan to the south to Deli Toewo (= Deli Tua) about Kampung Bahroe in attack. The route from Medan to Perbaeongan went about Serdang, which was developed in the 1890s as a center of coffee cultivation and Lubukpakam . From this location later southwards towards Bangungpurba branching routes served rubber plantations. Until 1890 of track had been completed. Bridges were built at that time for axle loads of . The crisis of the tobacco sales in 1894 at first prevented the financing of planned extensions to Arnhemia, Bangun Purba and Rampah. 1900 efforts were made to concessions for the upgraded lines Perbaoengan-Bamban (after 1904 extended until Tebingtinggi ) Timbang Langkat- Tandjoeng, Poera-Pangkalan Brandan. The routes were all created single track. The approval in 1913 greatly expanded. The distance of the end of 1921 the port was Besitang Pangkalan NONCNONC extended. From Salesseh you extended a short branch line south to Kwala (Kuala =) for the disposal of wood. From Tebingtinggi chain in the south a distance to Pematangsiantar from. This was the first real mountain section of the DSM, the first 8 km, the slope was 10 ‰, on the last 6 kilometers before Dolok Merangir one reached to 20 ‰. To use this section, four more locomotives, named after the place as Siantar type procured. Coastal closer the train was to Kisaran (1927 branch to the port Telukinibung ) over Tanjungbalai was begun in during the First World War. Kiaran-Goenting Saga (6.7 million fl.) Opened on 4 September 1924 the extension to Milano (5.2 million) on January 1, 1931. The Bridge over the Sungei Asahan was 75 m, the longest, which was built by the DSM. 110 km through hilly terrain of Kisaran, the section of the route from Milano to
Rantau Prapat, the last new mainline was before the war. She went into operation in 1937.. It began in 1935 with the laying of welded rails, making it one of the first railway companies, who introduced this technology. In addition to replacement of damaged locomotives and wagons in 1947 resulted in the need for having to replace about 200,000 old sleepers at short notice. The network was established to 1950 the extent that top speeds of 50 km / h were possible. Coal is moved after the war from West Sumatra. == Stock ==