After World War II, new locomotives and railcars were delivered to Turkey and used on the line. In 1962, new E8000 EMUs were ordered as part of TCDD's plans to upgrade the line. In the following years, the tracks were doubled and electrified, and the stations were all renovated. Beginning in late 1968, these EMUs started test runs on the line. On 29 May 1969 increased commuter service with the new EMUs began operation.Ergin Tonuk – Haydarpaşa tecrübe seferleri In 1971, new E40000 electric locomotives started to operate on the line. In 1972, E14000 EMUs were introduced, and the E40000 were put on regional service between İstanbul and Adapazarı. The route however deteriorated for the next three decades and during the mid-2000s, the EMUs were in bad shape and the tracks were in need of repair.
