Inheriting the traditional space-using in Japan, Tokyo City Garden proposes the variability of spatial functions. The function changes in different time. During day and night, Tokyo City Garden has different appearances to show the transition of function, to realize public transport automation. The timeline for switching the routine between train and people is the principal axis in transition of function. At night, the system will be a train station, Self-driving vehicle is a part of building space filling up the building and combining the appearance, supplying energy for train and become a new landmark in Tokyo. And during the day, Tokyo City Garden overturns the space to become vertical traffic evacuation. The vehicles scatter in the city, thus the appearance of building occurs in the city fragmentedly. For providing people public space, the building turns to be a vertical garden from parking lot, and gain highest effectiveness in urban space.