One of the strategic partners of Tbilisi Metro is ЗРЭПС. The basis for cooperation with ЗРЭПС was laid in 1997 by establishing a joint venture called Tbilisi Branch of ЗРЭПС.  The founders of the joint venture are Tbilisi Metro Ltd (50%) and Moscow ЗРЭПС (50%). The main business of the joint venture is to conduct current and major repairs of the trains of Tbilisi Metro. Since 1997 the joint venture has repaired 140 carriages.

By order of Tbilisi Metro, in November 2005 Tbilisi Branch of ЗРЭПС launched the first modernized carriage. Metro carriage modernization project was identified as one of the priority areas by Tbilisi Mayor's Office that allocates several million Lari from the local budget of Tbilisi to finance the project implementation.