The Taipei MRT Circular line is not only the first-ever circular route on the network, it is also the first of its type to adopt traditional vehicle design with steel wheels and steel rails for a medium-capacity transit system. Different from the rubber wheel system used on the inservice Wenhu line, the trains for the Circular line will be similar to the steel-wheel trains on the Danshui line except for smaller size and an automatic system with no driver or driver's compartment. The trains will be controlled by an advanced signaling system and will feature a streamlined exterior appearance, spacious carriages connected with gangways, and peoplecentric interior facilities to create a comfortable and pleasant riding environment for passengers. Since the vehicles are, at this moment, still in the concept design stage, this article aims to provide a general overview to help readers understand the design outlines of the upcoming newgeneration trains.