皇居新宮殿の実施案に反映された高尾亮一と吉村順三の設計思想

抄録

 The project of the Imperial Palace started with designing the draft plan by the Imperial Household Agency. Although the draft plan was approved by the cabinet, the realized version was significantly deferent. Therefore, it is assumed that the over all design concept was changed. The purpose of this paper is to show the design concept of the realized plan by analyzing the statements of Ryoichi Takao, who was leading this project after the cabinet's approval, and Junzo Yoshimura, who worked out the basic design. Moreover, this paper conducts an analysis of comparison of two designs to show the changes been made after the draft plan and design concept reflected the realized plan.

 As in the Takao’s opinion the appearance of the draft plan was intimidating, he changed the process of project management in order to alter its design. Yoshimura had been selected for the position of chief designer and design period was extended. Takao also proposed in design condition the idea to widen the forecourt in order to hold the general palace visit, and requested the design of the palace appearance to expresses a close relationship with citizens.

 At the expert hearing before the inauguration of the designer, Yoshimura claimed that the appearance of the new palace should be simple and light with no exaggeration, and express the Japanese tradition in the modern sense. On the other hand, after the inauguration, his statements mainly focused on the conservation of the surrounding historical landscape including Edo castle ruins and the relationship between the garden and building.

 The analysis of the realized plan shows its design is based on Takao and Yoshimura's ideas, as following. In terms of organization of plan (Fig. 1), the arrangement of seiden―the most formal building was changed, placed on the west side with its facade turn to the East, which allowed the ceremonial section buildings move to the west side, and enlarge the forecourt on the east side enough for the general palace visit. In connection with this, the car route was placed on the east and north side of the site, which allowed to enlarge the south garden designed in the draft plan. On the south part of the palace, the ceremony route for the attendance was arranged through the passage with no large room placed on it, which enabled them to gain a view to the garden.

 In terms of the appearance (Fig. 4, 5), Japanese style design of the palace emphasizing the horizontality was enabled through the development of the roof structure (Fig. 6). The copper roof with large eaves was meant to look light by gentle pitch of the roof and thin edge of the eaves. The facade of each building was composed by slender elements such as thin columns and vertical mullions of glass window, beams between upper wall and window. Besides, the parking lot was planned under the forecourt in order to make the facade and forecourt appearance (Fig. 8) neat and clean in consideration of the sequence of scenery when approaching from the outer garden of the Imperial Court (Fig9).