Within the scope of the High Speed Train (YHT) project, the train service between Haydarpaşa-Adapazarı was completely stopped as of 31 January 2012. For this reason, human circulation at the Izmit Train Station ended. However, the wagon circulation continues.
Within the scope of TCDD's High Speed Train project, trains will not work for two years. Izmit Train Station was given to the use of the contractor firm. In this context, it was requested to remove the long-standing Marmaray wagons at the Izmit Train Station. Marmaray wagons were taken from Izmit Train Station to Istanbul. In the meantime, Haydarpaşa Train Station is sent to the passenger car in the direction of Ankara. A part of the passenger wagons in Haydarpaşa Railway Station was brought to Izmit Station for a while.
Source : http://www.ozgurkocaeli.com.tr