Haydarpaşa-Adapazarı_Bölgesel_Ekspresi
The Adapazarı Express (Turkish: Adapazarı Ekspresi) officially listed as the Haydarpaşa-Adapazarı Regional (Turkish: Haydarpaşa-Adapazarı Bölgeseli) was a regional rail service, that ran between Istanbul and Adapazarı. For the majority of its time in service, it was the second-busiest route of the Turkish State Railways, after the Adana-Mersin Regional. Trains served a heavily populated region on the north-east shores of the Sea of Marmara and the Sakarya plain. Service was frequent with 12 trains daily in each direction in 2012. The Regional service also passed through important districts of Istanbul such as Kadıköy, Maltepe, Kartal, Pendik, Tuzla as well as Gebze, İzmit and Adapazarı. Because of the cities, the train service earned the nickname Metropolitan Express.[2] The train used to service Coşkunoğulları station until the TOE (Turkish Automotive Industry) factory was closed in 1991. It also serviced Acısu, Tepetarla and Kurtköy stations until 1998. Due to the construction of the Istanbul-Ankara high-speed railway, the Haydarpaşa-Adapazarı Regional service was discontinued on 1 February 2012 in order to upgrade the existing railway line. On 5 January 2015 service between Arifiye and Pendik was reopened with a new, faster regional service known as the Ada Express.