上海城市空间结构减载的经济学研究

【作者】 张伊娜；

【导师】 王桂新；

【作者基本信息】 复旦大学 ， 人口、资源与环境经济学， 2008， 博士

【摘要】 自布伦特兰报告-《我们共同的未来》,可持续性及可持续发展已经成为当今世界发展的主旋律。对未来世界环境及资源的关注,要“从城市响起,因为正是在这里,产生了最为严重的环境破坏,也只有在这里,许多问题才能得到有效的改善与解决。”(White,1994)。根据中央部署和上海发展战略,到2020年前后上海要初步建成“四个中心”和国际大都市。所以上海仍将处于加速发展阶段,也就基本决定了未来二、三十年仍将有大量外来人口向上海集中。高增长的人口规模,势必使上海遭遇越来越严重的环境问题、交通问题和社会问题等。城市减载问题迫在眉睫。与以往单纯控制大城市人口规模实现减载不同,本文从改善城市空间结构入手,为我国城市发展和城市人口规模控制提供了一条新的思路。然而目前理论界对什么是最优的城市空间结构形态模式仍有分歧;此外,城市是一个极其复杂的系统,每个城市主体都有其最优化的策略,又同时受动于其他主体,如何构建尽量符合实际发展的模型,给予决策指导?不同的城市各有其不同特点,什么是适合我国大城市可持续发展的模式?本文即是对这些问题进行尝试性地研究分析。本研究从城市空间形态不同观点的回顾、城市空间集聚与扩散的经济学分析、城市空间功能一体化模型综述的文献考证入手,分析当前已有研究的不足,从而确立本文研究的突破点:首先,突破传统经济学分析方法,从微观经济主体的新视角,对理论界争执的可持续空间结构形态进行复杂仿真模拟,得出适合中国大城市发展的最优的、有利于减载的空间结构模式,并指导上海的实证分析研究;其次,突破目前主流城市空间研究的一般均衡理论的分析方法,采用了以最新的复杂自适应系统理论为指导的多主体动态非线性模拟,使仿真结果更逼近真实的城市系统,为减载城市空间结构提出有力的,有技术研究支撑的政策依据。本文的研究内容主要有两大部分:一是探索大城市一般意义上的可持续发展的空间结构形态。利用Swarm计算机仿真模拟平台,探索城市中政府、居民、厂商等微观主体非线性互作互动而导致的城市空间结构的演化过程,模拟比较“集中模式”、“集中+分散模式”、“分散模式”三种城市空间结构形态下所决定的不同的通勤距离、支付地租和等制约条件下的环境负荷,寻找空间结构减载的普适性的结论,得出:大城市空间结构的优化有赖于“适度规模集聚的总体形态结构”、“功能一体的空间布局——减少通勤荷载”以及“政府公共物品供给对空间结构的干预影响”。二是以仿真模拟结论为依据,进一步考察上海的城市空间结构特征:首先从总体结构来说,上海呈现中心区高度集聚态势。都心部高密度人口的外迁主要迁向离都心部不远的城区边缘部和近郊区;市外迁入人口也主要选择迁向开发较“热”、发展较快、条件较好的近郊区。相比之下,远郊区则出现人口净迁出,形成相对的“过疏化”趋势。也就是说上海市内、外迁移人口对迁入地选择空间模式的相似性,使得两股迁移流叠加,连绵城市化的扩散蔓延趋势已经形成。而这种“集中式”的“一城独大”的“摊大饼”式的城市空间结构是最不利于城市可持续发展的空间形态。其次,从城市功能布局考量发现,上海居民的居住、工作、游憩三类主要活动空间的错位,导致了上海通勤负荷的大大增加。基普数据表明就业岗位密度的空间自相关性远高于居住人口密度的分布,即就业岗位具有更高的集聚性。也就是说在居住人口近年呈空间扩散趋势,而就业岗位则集聚凝固,依旧集中在中心城区,主要商业业态空间分布亦是如此。因此大部分居民需要长通勤距离到达工作地和购物地,大大增加了城市的负载。再次,从政府规划干预的角度来说,上海的“一城九镇”规划、“1966城镇体系”在第二层面“新城(新镇)”的设置过于分散,基本接近于仿真模拟中的“分散模式”,不利于新城人口规模规划,基础设施的集中建设规划。新城的设置过多考虑了区县间的平衡,没有适度考虑规模经济的效益。郊区新镇以居住功能为主,使居民无法在当地得到必要的就业、购物、娱乐等一体化公共服务,因而对中心城依旧有强烈的依赖。“三个新城”规划虽符合“集中+分散模式”的概念,但由于基础设施建设不配套,也很大程度上影响了新城对中心城区的“疏解”作用。此外上海对郊区城镇建设缺乏统一规划,且目标多变,也是郊区城镇一直发展不起来的重要因素。最后,在以上分析的基础上,明确提出了未来上海“发展规模新城、疏散密集中心城”的空间结构减载目标,以及城市空间结构减载的政府可行的干预手段:第一,加强公共物品配置的引导作用,制定连续的城市规划政策;第二,使公共物品配置的外部性内部化,达到帕累托最优,包括中心城区道路拥挤收费、发展权转移,中心城区基础设施建设的外部利益返还以补贴新城发展等;第三,结合社会福利改进,提出对中心城区随面积增大的递进式房价策略,有效地引导部分希望获得大面积居住的高收入阶层主动郊迁,扶持新城发展。更多还原

【Abstract】 From publication of the Report of the Brundtland Commission, Our Common Future, sustainability and sustainable development have already become the main tune of worldwide development. Cities are important for word environment and resource because ’they are the site where the human impacts on the environment are most evident and the opportunities for impact reduction are most concentrated’. (White, 1994)Based on central government deploy and Shanghai’s development strategy, till 2020 Shanghai needs build ’four center’ and international metropolis. So Shanghai is still on speedup development phase. This basically decides that in the future 20 or 30 years large amount of immigrated population will come to Shanghai. High population growth will certainly make environmental problems, traffic problems and social problems worse. It is urgent for rban optimization.Unlike former urban optimization strategy, which is realized only by population controlling, the paper presents a new way for urban development and population controlling, that is to improve urban spatial structure. However, present theories diverge on which one is the best urban spatial structure model. What’s more, city is a very complicated system and each has its own best strategy. It is also impacted by other subjects. How to build more practical development model and give decision-making suggestion? Different cities have different characteristics. Which developing model adapt to sustainable development for Chinese big cities? The paper mainly study on those problems.The paper starts with review on various viewpoints and with literature research of urban spatial convergence and diffusion and urban spatial function integration. This paper analyses former studies’ shortage and try breakthroughs. First, unlike traditional economic analysis methods, from new viewpoint of microeconomic agent, the paper makes complexity simulation on sustainable urban spatial structure and gets the best spatial structure which is adaptable for Chinese big cities’ development and which gives guideline for shanghai city demonstration study. Second, unlike most urban spatial studies which use common equilibrium theory analysis methods, the paper adopts the latest complexity and adaptability system theory, which makes simulation result more close realistic and comes up with more strong support for policy with technique study. The paper mainly includes two parts:First, the paper probes generally into common sense sustainable spatial structure system. Using Swarm-computer simulation platform, this part studies most non-linear micro-agents in city, which include governments, residents, manufacturers and so on, work on with each other and result in development process of urban spatial structure. The simulation compares commuter distance load, rent load and environmental load between ’centralization model’, ’centralization + separation model’ and ’separation model’. Based on those studies, this part comes up with generally suitable conclusion, that is: big urban spatial structure optimization relies on ’moderate scale centralization’s urban structure form’, ’function spatial layout-reduce commuter distance’ and ’ intervention influence by government public goods’. Second, using simulation result and inspiration, the paper studies Shanghai’s spatial structure characteristics demonstratively:For one thing, generally speaking, Shanghai presents highly scale centralization situation in urban center. Population in high dense heartland transfers to nearby urban skirt or suburb. Immigrants mostly chose nearby urban skirt or suburb which relatively develop fast and have good condition. Comparatively speaking, net population in exurb reduces and it shows ’too sparse condition’. That is to say, immigrants and emigrants have similar choice for migrant spatial pattern, and it results in two transfer current adding. Sequence urbanization diffuses and spreads. However, this kind of urban structure as ’big city’ or ’central model’ or ’rolling big cake’ is not good for sustainable development.For another, from the study of urban function, main function spaces, which include inhabitation, work and rest misuse, and they result in commuter distance greatly increased. Basic unit survey shows that spatial autocorrelation of employment posts density is far higher than that of density of inhabitation population. However, centralization of employment posts is freezing. It focuses on center. Main business spatial structure is also thus. So, most residents need long commuting for working and shopping. It increases greatly the load of city.Still more, from the viewpoint of government interference, Shanghai’s ’One City and Nine Towns’ plan, and ’1966 City and Town Network’ set too disperse in the second level which is new city or new town. Those two patterns are almost close to the ’separation model’ in simulation. This is not good for population scope planning and collective investment planning of infrastructure construction for new town. Settlement of new town pays more attention to equation of counties, but considers little of benefits of scale economic. The function of new town of suburb is mainly inhabitation. Residents can not get integrity service such as basic employment, shopping, entertainment and so on. So they depend greatly on central city. Although, ’Three New Cities’ Plan’ is accorded with the concept of ’centralization + separation model’ in simulation, new cities’ decentralization are not effective because of unmatched infrastructure construction. Lacks of total plan and sequent objectives are also important reasons why cities and towns of Shanghai suburb can not develop quickly.The last, based on the former analysis, the paper makes clear that the aim of optimization of spatial structure in future, which is ’develop scale new city, evacuate dense central city ’. The paper brings forward feasible interference measures for government on optimization of Shanghai spatial structure. First, enhance guiding role of disposition of public goods, make sequent city plan policy. Second, internalize externality of public goods deposit, reach Pareto Optimum including collect road crowd fee of central city, FAR transference, and external stakeholders of infrastructure construction in central city payback to new town for development and so on. Third, combined with improvement of social welfare, the paper suggests make ladder-like house price policy based on house area, effectively lead those high-income stratums who want to buy big area house move initiatively to suburb, support development of new town from the viewpoint of welfare economics.更多还原