 The MX3000 introduced a number of technical innovations to the metro . Regenerative brakes allow the dynamic brakes to feed the braking energy back to the power system via the third rail . The passengers also have air conditioning . The driver 's cabs are more ergonomic than in the older models , and the mirrors to monitor the platforms have been replaced with cameras and screens . The trains ' livery is white with gray detailing , instead of the former models ' red with blue detailing . For use in areas without a third rail , such as at depots , the trains are equipped with a 110 V battery . This will remove the need for shunting at the depots and cut costs . 
