In recent years the issue of public space in urban Japan has won great prominence. Since 2002 for example accredited street artists and vendors (re)appear in parks and streets of Tokyo as part of campaigns to promote Japan and its capital as attractive, bustling tourist destination. So-called 'Open Cafes' are proliferating in private plazas as well as public pedestrian malls, parks, or sidewalks in order to stimulate new public life in places were previously modernist paradigms of efficiency and functionality ruled such out, or to capitalise on a revival of outdoor life styles. Symbolic, beautified public spaces -parks, squares, promenades, waterfronts - are created to endow identity to local communities, or to brand office complexes and whole business districts. The growing professional interest in the quality of public space stands in a dialectical relationship with the increasing body of literature on the subject and related burgeoning discourses on civil society, citizen participation, public sphere, and the very concept of Public.

This thesis seeks to explore why there is such keen theoretical and practical interest in urban public space and the reasons for this changing focus on public space design and development. How have designers, developers and planning authorities approached public space in the past, and which factors have led to the current re-valuation? What are distinctive meanings of public space in Japan, and, how do those changing meanings influence its production, regulation and use? In order to account for the multiple actors and inanimate elements -texts, images of successful urban spaces - which equally contribute to the discursive negotiation of public space, the study adopts Actor-Network Theory (ANT) as a meta theoretical framework. Much recent writing points out the social construction of public space with the consequence that values and meanings ascribed to it are never fixed but vary among cultures, places and over time. Nevertheless, when it comes to analysing it in non-Western contexts, often Western views are presumed, which make it difficult to describe relevant phenomena in their own right and against their own conceptual histories.

Chapter one deconstructs therefore such dominant Western understandings of public space and contrasts them with intrinsic Japanese meanings and the particular ways these influence the evolution of urban space. After arriving at a workable definition and illustrating its dynamic social construction, an analytical framework is proposed, which accommodates the diverse policies, ideas, and actors, which inform the physical production of public space, and which are exemplified in the subsequent parts of the study.

Chapter two takes a critical historic perspective on the genealogy of public space in urban Japan within the wider context of the urban governance system, planning culture and other socio-economic transformations, as current urban developments cannot be adequately understood without a firm knowledge of their particular institutional (formal regulations as well as informal social conventions and social practice), physical and historical background. From the introduction of the first early-modern, western-style precedents -parks, sidewalks, squares, waterfronts- over comprehensive, open space visions of regional park systems in the inter-war and early post-war period, unitarily used public space came under jurisdiction of highly specialised, non-cooperative, at times antagonistic government authorities, impeding a more comprehensive understanding. An exclusive idea of the public good further eliminated an increasing array of activities and the rampant motorisation dissolved it in insular spaces. In recent years growing private influence and a growing number of successful local initiatives have led to a re-interpretation of public space and with it, the underlying very idea of the public. In global urban studies views prevail, which see mobile capital and multi-national corporations exerting a homogenising influence on urban space and lead to a worldwide convergence. As the guiding hypothesis of this research argues against such a priori simplifications, it looks in the second part into specific, influential projects, which promoted in their aggregation a re-definition of contemporary public space. In order to allow for a differentiated analysis of local and global, public, private or communitarian influences, the main part of the study is structured into three chief chapters:

Chapter three scrutinises groundbreaking, small scale projects, where local governments,residents, citizen activists, or external experts advanced unprecedented, alternative types of public spaces through new open planning processes, significantly deviating from established bureaucratic routines of former decades.

Chapter four looks at the growing private production of open spaces through incentive planning instruments, represented by an exemplary discussion of so-called privately owned public spaces (POPS). These are quantitatively highly significant and have been created in downtown areas since the late 1960s. In this form of public-private partnerships the public sector trades in the private production, ownership and management of publicly usable space for an incentive of bonus floor area bonus or other zoning concessions. Focusing on this specific type of public space doesn't simply serve as an end in itself. Its very appearance marked in fact a major turning point in urban governance, as the public sector relinquished its dominating role as sole provider of urban public space. Examining it allows therefore transcending conventional government-centred research frameworks by also appreciating values and meanings, attributed from the private side. As the real estate sector is most perceptive for changing socio-economic trends, it translates them into new built urban form following the logic of profit maximisation. Thus, the New Public Spaces of mix-use mega-developments like Ebisu Garden Place, Roppongi Hills, Shinjuku Southern Terrace, SIO Site Shiodome, Midtown or Marunouchi serve as indicators for established power structures as well as wider social trends of fusion of work and leisure, a longing for collective memory and shared narratives, a new awareness for environment and quality of life or the feminisation of urban space.

Chapter five takes a longitudinal, long-term perspective on the particular urban governance and planning culture of Yokohama City, one of Japan's most progressive local government, whereas the preceding two chapters focused on particular, innovative examples of new publicly and privately owned, publicly usable spaces. Since the 1960s a long-term strategic planning vision envisioned here a comprehensive reconquest of public pedestrian space under utilisation of private initiative for its realisation. Through intensive publication, initial deliberations in the public sphere of planning experts and later in the broader public, the integrated urban design approach exerted a strong influence on public space policies of other local governments, which finally added to a changed attitude of the national government towards the liveable city.

Chapter six summarises the findings of the preceding chapters and discusses the complex processes, which came to influence the production, management and use of urban public space, culminating in its current renaissance. While the quality of public space was important in early modernist planning during the 1920s and 30s, it fell into neglect in the post-war period. Scholars and local urban designers rediscovered quality public spaces as means for local identity promotion and participation in Machizukuri projects and beautification strategies during the 1960s and 70s. This was more and more taken up by the real estate sector for the creation New Public Spaces at large mix-use redevelopment schemes, were it served as distinguishing element in an increasing area competition, but also responded to changed socio-cultural values. In the struggle against the perceived loss of competitiveness of the world city Tokyo vis-a vis its burgeoning East Asian rivals, the government identified it also as means for city branding and image policies.

本論文は日本の近代以降の大都市における公共空間がいかに生成し、変転してきたかについて、開発者、行政、都市デザイナーなど各方面の関与者のそれぞれの立場から歴史的な分析を加え、近代日本の都市空間において公共性の概念がどのような位置にあるのかを明らかにしようとしたものである。研究を進めるにあたって、とりわけ私的に所有されているものの公共的に使用されている都市空間のあり方に着目し、そのデザイン手法を近代以降、もっとも最近の事例にまで踏み込んで調査分析し、その潮流を明らかにしている。

論文は研究の枠組みと研究の手法を述べた序章と5つの章から成る本論部分、そして結論を述べる6章によって構成されている。巻末に具体的な資料および参考文献を掲載している。

第1章は、序説であり、公共性の概念の検討を主として行っている。経済学的および社会学的、政治学的な公と私の関係の概括的な考察ののち、物理的な公共空間の画定に関して、公的空間と私的空間の中間に私的に所有されている公的な空間の領域が存在することを示し、この領域を研究の主たる視点として日本の公共空間の特質を歴史的および現象的に明らかにしていくという手法を提示している。

第2章および第3章は、近代日本において公共空間がどのように生成し、発展してきたかを通時的に明らかにする章である。第2章においては、明治初期より1970年代まで、日本における公共空間は都市の機能を充足するための空間であったことを明らかにしている。たとえば「交通広場」という概念にそのことは象徴的に現れている。続く第3章においては、1970年代以降の公共空間に関する新しい概念の生成を取り上げ、地方公共団体による多様な公共的な空間の確保事例を明らかにしている。これらを通して、私企業による開発計画へのアンチテーゼとしての公共的空間づくりの民間運動を概観し、いわゆるまちづくりの動きの中における公共空間の位置を考察している。

第4章は、第3章とは対照的に、私的セクターによって供給される公共的空間について論じている。日本においては1960年代以来の都市計画上のインセンティブとして公開空地などの公共的空間が私的セクターによって設けられてきた。そうして生み出された公共的空間の性格や私的セクターの行動規範等の分析を続けている。最終的には近年、東京において実現した巨大プロジェクト(六本木ヒルズ、汐留シオサイト、ミッドタウン、丸の内の再開発において私的セクターが作り出した公共的空間の具体的な特徴とその傾向を明らかにしている。

第4章が1970年代以降の動きを通時的に明らかにしているのに対して、第5章は、横浜市という単一の都市を事例として取り上げ、都市内の私的セクターが生み出した公共的空間の特徴を共時的に明らかにしている。特に公共的空間形成のための戦略的計画と地域レベルの総合的なマスタープランの重要性を、事例分析を通して明らかにしている。

結論を述べる第6章は、都市内の私的セクターが生み出した公共的空間の評価について、これを新しい公共空間の一類型として歓迎する初期の論調から、その商業主義や没総体性からこれらの公共的空間に疑問を呈する中期の議論を経て、公共的空間の「公共性」をより詳細かつ厳密に考察する近年の傾向までを総括している。

このような世界的な傾向の中で近年の日本の公共空間論議が、プロジェクトが生み出した具体的空間の評価に重点が置かれ、その「公共性」の検証が不足しているという現状を批判的に分析している。

以上、本論文は近代日本における公共空間の履歴と現況を具体的な事実を詳細に跡づけることによって明らかにし、特に私的セクターが生み出した公共的空間に着目し、その特質を明らかにしている。これらの作業を通して、日本の公共空間とそうした空間に関する認識の特質を明らかにすることに成功している。実証性に富んだ論述は今日の日本にとって有効な考察となっており、その有用性は非常に高いといえる。

よって本論文は博士(工学)の学位申請論文として合格と認められる。