Hypothesis of incomplete-structural matching job-housing in a polycentric city
ZHAOMiaoxi收稿日期:2017-03-24
修回日期:2017-07-3
网络出版日期:2017-08-10
版权声明:2017《地理研究》编辑部《地理研究》编辑部
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1 引言
1.1 源于实践的多中心职住问题
对于人口不断增长的大都市地区,如何在多中心规划中建立合适的职住体系,一直没有找到有效的解决方式。一方面,多中心就业—居住的总量不平衡影响了城市的空间绩效,例如多年来上海外围新城、新市镇的就业吸纳能力一直不足,北京的通州、广州的番禺等地,居住人口过度集聚形成了尴尬的“卧城”;另一方面,多中心规划实践还存在就业—居住的结构性不匹配,例如城市外围的新城、开发区附近看似庞大的无业群体却未必能符合企业需求,从而结构性地形成了职住的“空间失配”。该类问题中,第一类情形是就业、居住的总量相等和空间邻近,即一般意义上的“职住平衡”;第二类情形是必须在结构层面予以应对的“职住失配”问题[1]。两种情形构成了密切关联、但内涵深度不一致的议题：数量上的职住平衡并不是本地通勤的充分必要条件,而结构性的职住匹配更加接近多中心的理想目标状态。居住是城市社会空间的表达,就业是城市经济空间的反映,因此探索多中心的职住功能匹配问题,不能将其等同于职住的总量平衡,而应剖析就业、居住所投影的城市空间运行机制,为就业—居住的功能匹配寻求合意的理论模型。既有的多中心城市研究成果包括形态方面的多中心开敞、紧凑性、房价或者地价等议题[2-4],但对于多中心城市就业、居住空间匹配这一问题,尚未有针对性的理论梳理。基于既有的多学科文献,先逐项剖析既有的理论议题,再采取思辨的方式,探索合意的空间匹配模式,在此基础上给出相应的测度工具,并采用实证案例进行展示。文献理论梳理部分首先包括就业、居住作为城市基本活动的多中心功能组织,即从结构层面辨析就业、居住的组合问题,具体包括多中心的生成机制、就业中心的专门化集聚、功能多样性以及居住隔离的职住失配等4个平行的议题;另一方面,则是从交通组织的角度梳理多中心对于职住通勤的影响。
1.2 多中心城市功能组织的相关文献
1.2.1 多中心的生成机制 对于多中心城市的生成机制,经济学给出了完整的理论框架：即先从微观区位的角度构建单中心城市模型,以新古典主义的地租理论演绎生成圈层式的城市空间结构;多中心城市的分析框架与单中心相类似,通过比较工资水平、集聚经济的外部性、商品运输成本、个人通勤成本等约束条件,演绎生成不同参数条件下单中心—多中心的空间均衡状态[5,6]。相比于经济学领域的演绎研究,城市研究领域多从实证中进行特征归纳,其聚沙成塔的研究方式,形成了更为丰富的成果。Giumano等较早地对美国郊区的就业中心进行了定量研究,对于郊区化的过程有了相对准确的理解[7,8]。随后的相关实证研究大多以就业岗位数为着手点,通过就业密度、就业门槛值以及回归方程等方法测度就业中心的空间发育状态[9-11]。在巨型城市层面,Hall等还采用就业岗位、居住人口、通勤流、生产性服务业流等数据,对欧洲8个巨型城市区域进行了多中心的均衡性测度[12];Musterd等从家庭行为角度强调了多中心在社区层面的尺度意义[13],进一步丰富了多中心城市的内涵。
1.2.2 就业中心的专门化集聚 城市经济学的研究虽然也注意到了不同产业因为地租差异而形成的同心圆结构,但并没有注意到产业的集聚机理。针对现实中新城、新区的功能发育问题,探索多中心的就业分布离不开对产业功能集聚的研究。根据Krugman等的观点,集聚经济源自于企业邻近形成的共享技术溢出优势,而土地稀缺、交通拥堵等状况则是城市空间扩散重组的驱动力[14-16]。另一方面,消除单中心城市拥堵的负外部性并不等于“去中心化”或者“无中心化”,而是要在疏散的过程中保证集聚经济的正向外部性收益,否则,过度的空间分散将最终导向城市虚无主义,既有悖于人类社会发展的城镇化规律,也不符合马歇尔产业经济的集聚效应[17]。从这个意义上说,虽然“多中心”是与“单中心”相对应的一种空间形态,但就业的过度分散将削弱产业集群的正向外部性。基于这一约束条件,多中心城市必须在其内部的各个中心形成就业的专门化集聚[15,16,18],而非各种功能活动在诸就业中心之间的均匀分散。
对于多中心城市的功能组合议题,部分****还从区域的角度进行阐述。例如Burger等均强调多中心之间的互补性功能联系,其原理与马歇尔的集聚优势形成了内在逻辑的一致性,即就业中心的专业分工是实现功能互补的前提和基础[19]。Meijers还提出了“众多小规模城市之和是否优于大城市”的命题[20]。引申而言,按照亚里士多德的朴素系统论思想,多中心功能系统必须体现“整体大于局部之和”的基本特征,否则,多中心也就失去了存在的价值。
1.2.3 就业中心的功能多样性 对于城市中心来说,混合或者多样性是城市性的重要特征,相应地,多中心也必须具混合的功能[13,21]。部分****基于雅各布的多样性理论,将用地功能的混合作为识别城市次中心的重要依据[22]。在规划实践中,功能单一的产业园区不但了无生趣,还将导致钟摆式的单向通勤、最终妨碍城市系统的运行效率。
在城市集聚规模降低的前提下,结合就业中心的专门化集聚约束条件,多中心城市的功能组织模式需要就“专门化vs多样性”的对偶性问题进行解答。实证研究中,Leslie等研究发现,美国凤凰城地区既有专业化的CBD和次中心,也有多样化的郊区次中心[23];Gilli针对大巴黎地区的多中心演化研究则表明,就业的迁移促进专门化,而就业的增长促进多样化[24];Kemeny等从理论上对“专门化vs多样性”进行了辨析：专门化集聚主要面向地区间的可贸易（Tradable）产出,而多样性更多地是面向本地的非贸易（Non-tradable）产出,且多样性在“专门化vs多样性”的对偶性议题中处于从属地位[25];Simonen等认为,多样化能促进专业分工的进一步发展,且多样性具有边际效应递减的趋势特征[26]。
总体而言,多样性依赖于城市规模的集聚效应,对于以功能疏解、缓解“大城市病”为目标的多中心城市来说,特定地区就业规模的削弱将使得多样性在客观上受到一定损害,也就是说,既然选择了多中心的战略,就无法再苛求总体规模集聚的多样性效应,但专门化集聚依然能通过分散中的再集中予以实现。在这种情形下,按照“避免最坏情况”的规划底线,保障当地居民的日常生活需求成为功能多样化的基本要求。因此,可将就业中心多样性的功能目标从繁复的产业功能配置转向充足的居民生活服务设施,这也是多样化边际效应递减的具体应用[26]。卡尔索普针对美国郊区蔓延问题而提出的“新城市主义”,实际上也是基于人文关怀、从社区层面倡导功能的完善[27]。
1.2.4 居住隔离的空间失配 关于就业—居住匹配的重要研究还来源于空间失配（Spatial mismatch）假说。这一理论始自美国郊区化过程中、非裔群体过度集聚于市区所产生的居住隔离问题。1968年Kain发现,随着传统中心区就业岗位迁往郊区,居住在中心区的黑人因为较高的通勤成本失去就业机会,同时郊区的雇主也不愿意雇佣居住在内城的谋职者,由此形成了就业—居住的空间不匹配。Kain将其总结为“空间失配”理论[1]。一定程度上,社会隔离源自于单一群体的聚居,并导致社会多样性的不足。随着研究的不断深入,职住空间失配研究取得了丰富的成果。1970年代以后,相关研究更多地从城市规划的角度出发,侧重于城市空间的结构性和制度性影响。在这一趋势下,学术界对“空间失配”理论进行了重新界定,即空间失配研究的重点在于空间不平等,而非种族歧视问题[28,29]。
在多中心的职住体系中,就业的专门化集聚有可能产生单一群体的聚居从而形成事实上的社会隔离。这是因为,主导产业的专门化集聚虽然形成了就业中心之间频密的互补性功能联系,并在多中心内部形塑了Castells所说的精英型“流动空间”;然而,专业化精英人群构成的“流动空间”背后潜藏着社会空间极化的风险。网络社会中精英阶层成为全球性流动的主导者,同时有可能将特定的弱势人群排除在日常的城市网络之外,导致与社会隔离密切关联的空间失配[1]。由此通勤的社会排除效应更加明显,这也曾是美国郊区化的经验和教训[30]。
在国内城市的多中心建设实践中,部分开发区、新城逐步形成了专业技术人群的空间集聚,这类地区与当地社会隔离的趋势也成为新的规划议题。例如,2013年广东省住建部门的新型城镇化调研中,佛山市狮山镇（佛山副中心之一）的规划部门就曾表示,高新区的新驻企业一汽大众不应与本地社会分离。在理论层面,周江评较早地向国内介绍了空间失配学说,刘望保等归纳了各种职住失配的测度方法[29,31,32]。同时,随着市场转型的不断深入,以单位制大院为特征的居住—就业格局逐步瓦解,国内城市空间扩张产生的职住不匹配问题也就日益增多[11,33]。其中,关注弱势群体的职住通勤也已逐渐成为空间匹配的重要议题。
1.3 多中心城市交通组织的相关文献
在前述的城市经济学理论中,城市中心的形成源自于空间集聚的正外部性。多中心也是微观个体的收入、地租、职住通勤成本等约束下的一种空间形式,且单中心在规模集聚效应方面优于多中心;在另一方面,鉴于单中心拥堵的负外部性,Gordon等认为多中心是解决向心式通勤的一种方式[34-40]。由于多中心大都市地区的实际通勤情况较为复杂,关于单中心、多中心两种模式与通勤交通绩效之间的关系存在学术争论。例如,郑思齐认为,基于集聚经济优先的考量,单中心导致的职住分离是正常的市场机制[41]。基于更一般的观点,若就业多中心的空间结构将能有效分散单中心所聚集的交通量,还是能够降低居民的通勤距离和通勤时间[36-40]。案例研究方面,在兰斯塔德这一典型的多中心地区,20世纪80年代后期城市与近郊的通勤比例占全部交通量的41%[35,36]。Hall等对该地区2002年的职住自足性测度表明,4个较大城市的本地职住通勤比例超过50%。从负面案例来看,二战后英国的新城建设,职住分离导致的钟摆式交通成为大城市人口疏散的重要经验和教训,即新城人口应达到一定的门槛规模以实现职住的自足性平衡。
理论模式方面,Bertaud等对于单中心和若干多中心的交通组织进行了归纳（图1）：单中心模式a是向心式的交通出行结构;d模式是“城市村”式的自足性多中心体系,但这一模式过分强调本地职住通勤,在现实中并不存在（例如双职工家庭的就业地点往往不一致）;b和c两种模式中的随机性出行体现了多中心交通组织的复杂性,同时有效避免了a模式的钟摆式通勤[39-42]。
显示原图|下载原图ZIP|生成PPT图1单中心、多中心的城市交通组织模式[
-->Fig. 1Models of transportation for monocentric and polycentric cities
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2 多中心城市的职住匹配模型
2.1 多中心职住匹配的模式辨析
从前述理论辨析可以看出,多中心城市就业、居住的空间匹配并非仅仅两者之间的结构性匹配,更不是一般意义上的职住总量平衡,而应体现就业、居住内部组分的深层次组合优势,以合乎城市的发展动力和系统运行机制。既有的研究中,Bertaud的单中心和多中心模式比较主要针对交通而言,并未分析多中心的职住空间组织。即没有考虑就业的多中心专门化集聚、弱势群体的居住隔离及通勤需求等因素,从而忽略了城市空间结构的一般规律和规划的价值取向。为此,以双组团城市为例,进行多中心就业—居住空间组合的模式比较。2.1.1 模式I：职住完全分离的组团模式 如图2a所示,在这一双组团城市模式中,组团1的就业功能A/B/C与组团2的居住功能a/b/c完全分离,就业功能的集中是空间集聚外部性的体现[41],保证了马歇尔的产业集聚优势。但是这种职住分离模式中,单一的产业功能组团或者居住组团都是乏味的,不具吸引力的,居住地区难以有效形成组团中心。组团2为典型的“卧城”,两个组团之间存在明显的钟摆式通勤。
显示原图|下载原图ZIP|生成PPT图2不同职住匹配形式的多中心模式
-->Fig. 2Polycentric model for different job-housing types
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2.1.2 模式II：完全匹配、职住均匀分散的组团模式 在模式II的两个组团中,无论是就业（A/B/C）还是居住（a/b/c）,每一组团都有着同样的就业门类结构,A-a、B-b、C-c的职住空间组合实现了完全匹配（图2b）。但是这一种空间模式实际上是城市中心功能的一种均匀分散,因为两个组团均是完全独立的城市,而非一个城市的两个部分,不符合“1+1>2”的系统性要求。两个组团的就业中心并不形成Meijers等所说的功能互补性,对于专业分工的放弃丧失了多中心城市所应有的系统性优势;且在交通方面,这种方式属于Bertaud所说的“城市村”模式,即过分强调职住的结构性匹配,忽视了交通出行随机性的社会现实。进一步地,在此种职住完全匹配的模式中,社会个体的就业地点存在周期性变动的可能,双职工家庭难以同时满足就地通勤[41]。
2.2 非完全匹配的假说模式
鉴于职住完全分离有悖于城市交通组织原则（模式I）,完全匹配的职住空间在多中心体系中又无法实现就业的专门化集聚（模式II）,研究尝试探索非完全的结构性匹配模式。对于局部的匹配性问题,首先要厘清哪一部分群体需要保证职住的空间邻近。在职住匹配的议题中,虽然部分就业问题源自于居住隔离下的空间失配,但混合性居住策略并不是解决社会隔离的最好方式,其实际政策效果也存在争议[1,43]。这也意味着,在多中心就业专门化集聚的约束下,微观个体的职住邻近选择有可能形成特定居住群体的空间区隔,也有可能存在长距离的通勤出行,市场机制下的随机性过程成为一种空间现实。但从规划针对的目标人群来看,问题在于如何缓解弱势群体的交通出行成本,即关注部分通勤距离受限群体的职住空间关系。
研究由此提出非完全的多中心职住匹配假说,即针对具有短距离通勤需求的特定弱势群体,尽可能满足该部分群体的职住邻近需求。特别地,尽管存在交通补贴的替代性可能,但出于照顾家庭、机动性不足等原因,部分人群的本地通勤依旧需要在空间上予以保障。在这一约束条件下,若能提供充足的面向本地居住生活服务的就业设施,城市功能在各个副中心仍可形成就业均衡的专门化集聚,即存在多中心就业—居住非完全匹配的可能。在近期的研究中,Burger等分析了兰斯塔德地区不同类型的拓扑网络,其中以通勤流为代表的日常生活联系就近指向各个城市,而商务流则以各个中心之间的联系为主导[44]。这也说明,各个中心之间的专业性商务联系与部分的本地通勤在现实中是可以并行不悖的。
在非完全匹配的假说模式中（图3）,组团1以A门类就业为主导职能,组团2以B门类就业为主导职能,就业结构反映了组团之间的功能互补;相较于每个组团均有3类就业的模式II,非完全匹配模式降低了每个组团就业门类的多样性要求,但是保障面向本地居民需求的就业设施供给（C类）;不追求A-a、B-b、C-c从业群体的职住完全匹配,但在各自组团内保障通勤受限的居住群体s与相应就业职位S之间的临近性。在图3中,S-s空间匹配的斜线覆盖区域包含各类就业群体中通勤受限的人群。
显示原图|下载原图ZIP|生成PPT图3假说模式：职住非完全匹配的多中心模式
-->Fig. 3Polycentric model with job-housing partly matched
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因此,对比前述模式I、模式II两种情景,假说模式包括4个方面的特征（表1）：首先,在空间层面依旧体现为均衡的就业多中心体系,保证就业中心的门槛规模;其次,在产业层面表现为就业中心的专门化功能集聚,以此实现经济空间秩序的系统性优势;再次,具有充足的设施以满足本地居民的日常生活需求;最后,保障低收入阶层的本地通勤可能,避免社会弱势群体的“职住失配”。
Tab. 1
表1
表1多中心职住匹配的不同模式比较
Tab. 1Comparison different models for matching job-housing in a polycentric city
| 特征 | 模式I | 模式II | 假说模式 |
|---|---|---|---|
| a. 就业空间均衡性 | 就业总量不均衡,形成“卧城” | 就业总量的多中心均衡 | 就业总量的多中心均衡 |
| b. 就业专门化程度 | 就业的专门化集聚 | 就业均匀分散、没有专门化集聚 | 就业的专门化集聚 |
| c. 居住设施充足性 | 就业、居住内部多样化,但组团整体功能单一 | 组团整体功能和就业、居住内部均多样化 | 就业弱多样化、但保障生活设施的充足性 |
| d. 本地职住通勤 | 钟摆式交通,不保障任何本地通勤 | 全部本地通勤,不现实的“城市村”交通模式 | 保障部分群体的短距通勤,随机性出行的多中心 |
| 职住匹配程度 | 完全分离 | 完全匹配 | 非完全的匹配 |
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3 多中心职住非完全结构匹配的测度
基于前述非完全匹配的假说模式,研究尝试建立多中心就业—居住空间匹配的测度模型。首先要对前置性条件予以确认：一是就业中心的空间识别,二是通勤成本受限群体的界定。其中,前者是判定多中心均衡性的前提,后者是判别是否存在空间失配社会风险的依据。对于多个就业中心的判定,可采用多种方法进行次中心的空间识别[8,10,11,45]。采用负指数模型拟合就业多中心：
式中：Dm为m点的总就业密度或者通勤流入的就业数;Dmn为m地到往潜在通勤的就业中心n的距离;An、bn为正的系数;vm为m点的误差项。通过逐步回归方程的决定系数、各项潜在中心的显著性即可判别是否属于次中心。
对于另一个前置条件,如果有全样本的交通出行调查数据则较易区分本地通勤的需求群体,若无法侦知本地通勤的真实需求,可以采用抽样方法,对人群进行分组后以假设检验（例如卡方检验、t检验）的方法,从统计意义上确定通勤距离受限的社会阶层。
在此基础上,采用各片区就业人数的累积差异来计算空间维度的多中心均衡性。对于具体的多中心指数,Hall等曾采用相对比例的累积差值方法。本文在沿用累积差值的思路基础上,对Hall等的多中心测度公式进行改进：定义i、j中心吸引范围内的就业岗位为Ei、Ej,先以累积差异计算就业多中心体系的均衡性：
式中：P为城市的多中心均衡程度;n是城市中全部的中心、次中心数。P值在0~1之间,该数值越高意味着多中心程度越明显,反之表现为单中心。
其次,专门化集聚是体现大都市产业分工的必要条件,由此体现为就业的多中心空间绩效,相应的测度方法可以借鉴Krugman专业化指数的变换形式[46]：
式中：S为专门化分工指数;Ei,m和Ej,m分别为i、j产业门类中m类就业岗位数。一般情况下,S值在0~1之间,该数值越高意味着多中心的高附加值产业专门化集聚越明显。
第三,按照前述假设,城市存在通勤交通制约的部分就业群体,这类人群的职住邻近性有其必要性,相应的测度方法可以在Gordon等非相似性测度的基础上予以改进[34,47]：
式中：D为大都市需求短距离出行的本地通勤指数;ELi,k、RLi,k分别为次中心i通勤范围内的k类低收入就业岗位数。一般情况下,D值也在0~1之间,该值越高意味着城市的低收入人群职住平衡越好,即社会弱势阶层的本地通勤比例越高。
根据前述理论,多样性就业设施从属于多中心的专业化分工,但要求具有充足的、面向本地居民的服务设施,对于这一基本保障,至少要求就业副中心中面向居住人口的各类当量设施不低于全市人均水平。首先以0/1的哑变量定义单项就业设施的充足性：
式中：ESi,l、Ri分别为次中心i的l类服务设施就业人数、次中心i的居住人数。对于本地消费的就业设施而言,采用所有中心的各类设施平均达标项数进行度量,设本地居民服务型就业设施一共h类,对n个城市就业中心计算整体的设施充足性。
总结式（2）~式（4）、式（6）可以看出,多中心均衡性测度和就业专门化集聚使用了总的就业密度（或就业通勤流入量）,职住结构性匹配只针对短距离的本地通勤需求人群,以充足的就业设施保障本地居民的生活需求。这4个维度反映了多中心职住模型的非完全结构匹配特征。多中心的均衡性P值、就业中心的专门化集聚程度S值、短距离通勤群体保障程度D值、居民服务型就业设施充足性I值均在0~1之间。若对4项数值进行几何平均值的计算,可得到综合性的就业—居住空间匹配多中心指数P''值（图4）。
显示原图|下载原图ZIP|生成PPT图4多中心职住非完全匹配的测度模型
-->Fig. 4Measurement of incomplete matching job-housing in a polycentric city
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4 基于广州的案例分析
4.1 数据来源
理论辨析为实证提供了一个可供参考的测度分析模型。以广州为例,以2000年人口普查的居住地数据对应于2001年基本单位普查的就业地数据,以2010年人口普查的居住地数据对应于2008年经济普查的就业地数据,近似地测度广州市就业—居住的多中心匹配趋势。由于大城市一般的通勤距离在12 km以内,相比之下,广州中心城内街道的面积尺度较小,而外围的镇街（多为30~50 km2）则能容纳这一通勤尺度,因此相应数据的空间尺度在中心城内采用行政区为单元,外围采用镇街为分析单元。对于通勤受限的群体划分,将制造业、建筑业、运输业、商业零售及批发等列为潜在的本地通勤人群,其余为高职业地位人群,并运用天河区1322例社区调研的有效数据（图5）。该调研于2014年12月完成,是天河区社区调研的基础数据,涵盖了社区居住、公服设施、社区公园、交通出行等方面的基本情况。对于受访者是否在天河本区通勤上班的问题进行交叉列联表比较。制造业、建筑业、运输业、商业零售及批发业人群,在天河本区就业比例明显高于其他人群,卡方值χ2为4.022,双尾检验的P值为0.045<0.05具有显著意义,说明职业地位的划分对于是否本地通勤具有较好的区分度。
显示原图|下载原图ZIP|生成PPT图5天河区受访居民的就业通勤分布
-->Fig. 5Distribution of respondents' job-housing commuting in Tianhe District
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对于面向本地居民的就业设施,基于2001年和2008年名录数据,采用教育、卫生、体育、社会福利、文化艺术、居民服务、基层管理、零售业等八大类设施的就业人数。
4.2 就业中心的识别
在多中心识别过程中,首先从2008年就业空间分布考察次中心的分布,进行多中心的负指数模型回归。这一过程中,任意一个空间单元除了市中心以外纳入最近的两个次中心,以反映通勤吸引的邻近性特征。以后退法逐步回归的方式进行检验,最终留在回归方程的包括广州主城区（CBD）以及花都狮岭、萝岗开发区、增城新塘、番禺市桥等次中心,相应的P值均小于0.05具有显著意义,说明这一主四副的就业多中心具有较高的拟合程度（限于篇幅方程从略）。对比《广州市城市总体规划（2011-2020）》的“1-2-3”多中心城市空间结构,花都、萝岗得到了体现,番禺市桥则是相对独立的次中心,说明广州主城区与番禺之间的就业地带呈现出非连续的分布状态,同时增城的副中心是新塘镇而非传统意义上的荔城街,意味着增城、从化的区级行政中心驻地尚不足以形成与主城区相并列的次中心,作为外围的规划中的南沙滨海新城也未发育成熟。4.3 多中心的职住匹配测度
在满足前置性条件的基础上,测度2001-2008年广州多中心的职住匹配程度。分别计算多中心均衡性（P值）、产业专门化集聚（S值）、本地居住配套的就业设施充足性（I值）、通勤受限群体的本地职住匹配性（D值）。经计算的分析结显示（图6）：广州2001-2008年间就业总量规模的多中心程度出现了一定上升（P值从0.809上升至0.833）,主要是外围的就业中心得以发育,尤其以增城新塘最为明显;次级中心的公共设施充足性也有所上升（E值从0.313上升至0.359）,说明花都、增城新塘、番禺市桥等地的公服设施配置逐步得到完善,尤其是白云新城的设施配套得到了较大的提升;但是产业功能的专门化集聚指数有所降低（S值从0.492下降至0.466）,意味着各个就业中心之间的专业分工出现了略微下降的趋势,不利于产业的区域竞争力培育;同时,居住的社会融合度更有明显下滑（D值从0.768下降至0.533）,通勤受限群体的职住匹配程度出现了明显的下降趋势,尤其是2000年以来,广州中心城“退二进三”的产业转型、致使部分制造业从业群体面临着突出的长距离通勤问题。总体上,广州的城市空间结构在就业总量、设施分布上有一定的多中心演化趋势,但在就业功能专门化集聚、保障短距离通勤群体的维度上明显不足,致使广州市综合性的多中心指数出现了下降。
显示原图|下载原图ZIP|生成PPT图62001年和2008年广州市的多中心职住匹配测度
-->Fig. 6Measuring job-housing of spatial matching in Guangzhou in 2001 and 2008
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要说明的是,针对广州案例的测度模型展示仅仅是事实的一般性描述,对于背后的机制还应进一步探索,例如既有的文献指出,城市规模、交通可达性要素对大都市外围次中心的形成都有潜在的影响[48-50],该类研究对于多中心职住的非完全匹配过程提供了诠释基础。
5 结论
多中心城市是缓解大都市地区职住通勤的一种空间模式,但是既有研究往往片面强调“田园城市”的分散理念,自足性的职住议题也仅关注就业、居住的总量平衡,忽视了规模集聚的正向外部性、职住空间匹配的结构性问题。基于此,针对就业——居住的匹配问题,辨析了多中心职住空间的功能组合模式;在此基础上,提出了非完全结构匹配的多中心职住假说模型：即在就业多中心均衡性的前提下,保障通勤距离受限群体的职住邻近性、满足本地居民的就业设施类型的完善,并通过就业中心的专门化功能集聚、实现多中心“整体大于局部之和”的系统性优势。针对广州的案例分析表明,广州的城市空间结构在就业总量、生活设施分布方面有一定的多中心特征,但在就业功能的专门化集聚、保障短距离通勤群体两方面依旧存在不足。要说明的是,学术界关于多中心的空间绩效尚待进一步实证,本文关于广州职住空间匹配的案例分析也仅仅是假说模型的展示,毕竟,在推理逻辑层面,案例分析的合理性取决于理论假说前提的合理性。本文关于多中心城市的职住空间匹配模式基于理论辨析而成,模型的建构虽然反映了既有文献的一般性共识,但不能将理论模型直接作为多中心实践的检验标尺,本文也因此承认知识产出效度的局限性,这种局限性既源自于当前文献积累的阶段性（甚至包括部分学术争议）,也来自于作者对于城市复杂巨系统认识的可能不足。因此本文多中心城市就业—空间匹配的测度模型只是初步的分析,理论假说的正确与否都必须在实践中对模型的约束条件不断予以修正、完善,方能逐步推进普遍性的规律和认识。
The authors have declared that no competing interests exist.
参考文献 原文顺序
文献年度倒序
文中引用次数倒序
被引期刊影响因子
| [1] | . |
| [2] | |
| [3] | . . |
| [4] | . Abstract In the past decade, Beijing has experienced dramatic spatial restructuring. In this paper, we test whether the conventional monocentric model of urban spatial structure can explain recent developments in Beijing’s land market. Using official land transaction data from 2008 through 2012, we find that (1) for commercial, mixed-use, and residential land parcels, both land prices and development intensities do not decline with distance from the urban center; (2) for industrial land parcels, land prices increase with distance from the urban center. These insignificant and positive land-price gradients defy the predictions of the monocentric model; such results are explained by examining Beijing’s evolution from a monocentric to a polycentric spatial configuration, which has been driven by various urban planning efforts and institutional reforms. Our analysis of post-Olympic Beijing land market dynamics leads to a fresh understanding of the city’s emerging polycentric metropolitan structure. |
| [5] | . |
| [6] | . |
| [7] | . This study examined commuting using disaggregate data in a larger and more dispersed region than has been analyzed before: the urbanized portion of the 5-county Los Angeles region. The data included 1980 journey-to-work information for 1146 zones. The existence of substantial excess commuting for the overall region was demonstrated, and it was examined at the level of sub areas, and at the level of individual employment centers. The study then examined whether this excess commuting is caused by mismatches between the locations of jobs for specific occupational groups and the location of houses suitable for members of those groups. The study results suggest that commuting distance and time are not very sensitive to variations in urban structure, and are far in excess of what can be explained by jobs-housing imbalances. It was concluded that the behavioral assumption of cost minimization in the standard model is inadequate to explain commuting, and that large scale changes in urban structure designed to promote jobs-housing balance would have only small effects on commuting. |
| [8] | . This paper uses data from the journey to work portion of the 1980 Census to estimate a polycentric model of employment density for the Chicago urbanised area. Distance to the Chicago central business district exerted a strong effect on employment density, but density was also influenced by proximity to three suburban employment centres. Some 27 per cent of total employment growth in metropolitan Chicago over the next decade was concentrated in these three subcentres. |
| [9] | . We review and test Fujita and Ogawa's [Regional Science and Urban Economic 12 (1982) 161 196] model of urban spatial structure. The central theoretical prediction is that the number of employment subcenters rises with population and commuting costs. Simple Poisson regressions for a sample of 62 large American urban areas provide strong support for the theory, and these two variables alone account for nearly 80% of the variation in the number of subcenters. The results imply that an urban area with low congestion develops its first subcenter when its population reaches 2.68 million and its second subcenter at a population of 6.74 million. |
| [10] | . 基于广州市第五次和第六次人口普查中的常住人口数据,运用空间分析法、单中心密度模型和多中心密度模型分析法对广州市人口空间分布和多中心城市空间结构进行研究。结果表明,研究时段内广州人口空间动态变化表现为"内圈层(近郊区)快速增长、外圈层慢速增长、核心圈层(核心区)和外圈低速增长",核心圈层的人口继续增长并向四周扩散,表明广州人口变动的郊区化现象明显,已呈现多中心特征,由2000年的"1个中心(人民公园)2个次中心(白云区的新景街和海珠区的凤阳街)"演变至2010年的"1个中心(人民公园)4个次中心(白云区的同德街、海珠区的凤阳街、天河区的棠下街和沙河街)",次中心的人口集聚功能逐渐增强,对城市人口分布影响逐渐增大。 . 基于广州市第五次和第六次人口普查中的常住人口数据,运用空间分析法、单中心密度模型和多中心密度模型分析法对广州市人口空间分布和多中心城市空间结构进行研究。结果表明,研究时段内广州人口空间动态变化表现为"内圈层(近郊区)快速增长、外圈层慢速增长、核心圈层(核心区)和外圈低速增长",核心圈层的人口继续增长并向四周扩散,表明广州人口变动的郊区化现象明显,已呈现多中心特征,由2000年的"1个中心(人民公园)2个次中心(白云区的新景街和海珠区的凤阳街)"演变至2010年的"1个中心(人民公园)4个次中心(白云区的同德街、海珠区的凤阳街、天河区的棠下街和沙河街)",次中心的人口集聚功能逐渐增强,对城市人口分布影响逐渐增大。 |
| [11] | . . |
| [12] | . ABSTRACT Book description: 'Large polycentric city-regions pose perplexing problems to social scientists and policy-makers. Not only do they represent complex socio-economic systems in their own right, but they also increasingly function as the main locational anchors of wider globalization processes. This book provides a masterful analysis of these issues, with a particular focus on the emergence, dynamics, and planning of polycentric city-regions in contemporary Europe' Allen Scott of University of California, and author of Global City-Regions. A new 21st century urban phenomenon is emerging: the networked polycentric mega-city region. Developed around one or more cities of global status, it is characterized by a cluster of cities and towns, physically separate but intensively networked in a complex spatial division of labour. This book describes and analyses eight such regions in North West Europe. For the first time, this work shows how businesses interrelate and communicate in geographical space - within each region, between them, and with the wider world. It goes on to demonstrate the profound consequences for spatial planning and regional development in Europe - and, by implication, other similar urban regions of the world. The Polycentric Metropolis introduces the concept of a mega-city region, analyses its characteristics, examines the issues surrounding regional identities, and discusses policy ramifications and outcomes for infrastructure, transport systems and regulation. Packed with high quality maps, case study data and written in a clear style by highly experienced authors, this will be an insightful and significant analysis suitable for professionals in urban planning and policy, environmental consultancies, business and investment communities, technical libraries, and students in urban studies, geography, economics and town/spatial planning. |
| [13] | . Recently, the use of the term polycentric or polynuclear urban region has clearly increased greatly in the European urban (planning) literature and also in policy documents. Literally, polycentricity in urban form refers to nothing more than the existence of more than one centre in a city, region or other geographical unit. It is not surprising to find that many more specific elements have been added to this rather broad and empty definition. These additions are strongly contingent on the viewpoint of researchers, especially with respect to the geographical unit that is being referred to. In this contribution, the different concepts and definitions are discussed from the perspective of changing households and related changes in activity patterns and residential preferences. We argue that, from a household perspective, polycentric urban regions the size of the Randstad or Rhine Ruhr area are too large to constitute relevant geographical units. However, at more local spatial level, the notion of polycentricity is relevant. Rather than focusing on the size of the urban region too much, we believe it makes sense to look at residential milieus. Over recent decades, households have diversified and have, on average, become more affluent and mobile, resulting in increased opportunities for choosing both a house and a residential environment. Simultaneously, polycentric milieus with different sub-milieus have emerged. In this contribution, it is argued that, together, these developments have made the functional uniqueness and complementarity of places more important. Therefore, the unique, spatially bounded qualities of places should play a more prominent part in the development of residential environments in polycentric urban areas than they do at present. Data from the Netherlands are applied to illustrate our viewpoint |
| [14] | . |
| [15] | . ABSTRACT Urban agglomeration becomes increasingly important because of the globalization of world economies. This paper is a general equilibrium analysis of urban agglomeration economies due to product variety, and agglomeration diseconomies due to intra-city congestion in a two-city system framework. Special attention is paid to the impacts of transportation cost decrease on urban concentration and dispersion. Our main result is that dispersion necessarily takes place when the transportation cost is sufficiently low. We also conduct numerical calculations using specific parameter values, and depict a structural transition from dispersion to agglomeration, and then re-dispersion when the transportation costs decrease monotonically over time. Finally, we observe that dispersion is usually bad as compared to agglomeration, from a welfare point of view. |
| [16] | . This Paper studies the theoretical micro-foundations of urban agglomeration economies. We distinguish three types of micro-foundations, based on sharing, matching, and learning mechanisms. For each of these three categories, we develop one or more core models in detail and discuss the literature in relation to those models. This allows us to give a precise characterization of some of the main theoretical underpinnings of urban agglomeration economies, to discuss modeling issues that arise when working with these tools, and to compare different sources of agglomeration economies in terms of the aggregate urban outcomes they produce as well as in terms of their normative implications. |
| [17] | . |
| [18] | . This paper examines the decentralization of employment using zip code data on employment by industry. Most American cities are decentralized--on average less than 16 percent of employment in metropolitan areas is within a three mile radius of the city center. In decentralized cities, the classic stylized facts of urban economics (i. e. prices fall with distance to the city center, commute time rise with distance and poverty falls with distance)no longer hold. Decentralization is most common in manufacturing and least common in services. The human capital level of an industry predicts its centralization, but the dominant factor explaining decentralization is the residential preferences of workers. Political borders also impact employment density which suggests that local government policies significantly influence the location of industry. |
| [19] | . Empirical research establishing the costs and benefits that can be associated with polycentric urban systems is often called for but rather thin on the ground. In part, this is due to the persistence of what appear to be two analytically distinct approaches in understanding and measuring polycentricity: a morphological approach centring on nodal features and a functional approach focused on the relations between centres. Informed by the oft-overlooked but rich heritage of urban systems research, this paper presents a general theoretical framework that links both approaches and discusses the way both can be measured and compared in a coherent manner. Using the Netherlands as a test case, it is demonstrated that most regions tend to be more morphologically polycentric than functionally polycentric. The difference is largely explained by the size, external connectivity and degree of self-sufficiency of a region's principal centre. |
| [20] | . |
| [21] | . |
| [22] | . We examine Mexico City urban structure through a composite index by combining two previously existing metrics: one derived from the Urban Network Analysis tool (UNA), recently published by MIT researchers, and the other, using an Entropy Index, which in essence, represents the mixed land-use degree. The proposed composite index embodies a different approach from previous methods reported in the literature because it uses disaggregated data at the unit level, performs weighted cluster calculations through a network data set, and incorporates a mixed land-use metric. This method was developed in order to test if the urban arrangement showed signs of a polycentric condition under a particular centrality standpoint. We observed that Mexico City has a relatively weak polycentric urban condition. |
| [23] | . |
| [24] | . |
| [25] | . This paper asks whether worker utility levelscomposed of wages, rents, and amenitiesare being equalized among American cities. Using microdata on U.S. urban workers in 1980 and 2000, little evidence of equalization is found. Comparable workers earn higher real wages in large cities, where amenities are also concentrated. Moreover, population growth between 1980 and 2000 has not been significantly different in low- and high-utility cities, suggesting that other forces are at work shaping the sorting processes that match workers and firms. We outline an alternative view of the drivers of change in the American urban system, and urban development more generally, by applying theory from economic geography. |
| [26] | . By Jaakko Simonen, Rauli Svento and Artti Juutinen; Specialization and diversity as drivers of economic growth: Evidence from High-Tech industries |
| [27] | |
| [28] | . The spatial mismatch hypothesis postulates that employment deconcentration within U.S. metropolitan areas goes some way toward explaining higher unemployment and lower wages among ethnic minority groups, since these groups are more likely to reside in central-city areas. However, little consensus has emerged on the importance of spatial mismatch in explaining disadvantage in the labor market. This article argues that conflicting evidence is the result of the variety of methods that have been used to test the spatial mismatch hypothesis. Moreover, it draws attention to a number of hitherto uncovered flaws in some of these methods that introduce systematic biases against finding evidence in support of the hypothesis. In light of these flaws, favored methods for future research are highlighted. Drawing on evidence from British conurbations that display similar spatial inequalities to U.S. metropolitan areas despite much smaller ethnic minority populations, the article contends that race does not lie at the heart of the spatial mismatch problem. Three areas in which the spatial mismatch hypothesis should be reconceptualized are identified: first, its emphasis should be on spatial, not racial, inequalities; second, it needs to differentiate between residential immobility and residential segregation, which are quite different; and third, it needs to recognize that theextentand theeffectof spatial mismatch are distinct and should be measured separately. |
| [29] | . . |
| [30] | . This paper introduces a mobility dimension to social exclusion, suggesting a strong correlation between a lack of access to adequate mobility and lack of access to opportunities, social networks, goods and services. This correlation exists as both a cause and consequence of social exclusion. The authors question the likelihood that increased physical mobility, by car or public transport, can, by itself, provide a fully viable or sustainable solution to mobility-related aspects of social exclusion. This paper cautiously suggests that the use of information and communications technologies could enable a new, virtual mobility, enabling an Internet-based increase in accessibility as an alternative to an increase in physical mobility. Finally, consideration is given to the possibility of a virtual mobility-related dimension of exclusion and to the possible social implications of inclusion of virtual mobility in an integrated transport strategy. |
| [31] | . 通过系统研究美国****60年代以来关于“空间不匹配”的假设与部分大城市弱势群体(如低收入居民、少数民族和妇女)就业问题,逐一梳理了美国****如何看待大城市弱势群体就业障碍问题以及他们所主要采用的研究方法和模型的演进过程。在此基础上,结合国内的实际情况,给国内学术界对城市弱势群体就业和再就业的研究提出4点借鉴和启示。 . 通过系统研究美国****60年代以来关于“空间不匹配”的假设与部分大城市弱势群体(如低收入居民、少数民族和妇女)就业问题,逐一梳理了美国****如何看待大城市弱势群体就业障碍问题以及他们所主要采用的研究方法和模型的演进过程。在此基础上,结合国内的实际情况,给国内学术界对城市弱势群体就业和再就业的研究提出4点借鉴和启示。 |
| [32] | . 西方“空间不匹配”假说认为，工作岗位的郊区化和美国城市中普遍存在的居住隔离是内城少数民族群体失业率较高、收入相对较低和通勤时间较长的重要原因，并将增加内城工作机会、改善内城区与郊区的交通联系等作为消除“空间不匹配”的重要手段。与西方相比，中国的相关研究仍比较薄弱，应在借鉴西方相关研究成果的基础上，形成自己独特的研究视角和分析方法，为解决社会弱势群体就业的空间障碍问题提供参考。 . 西方“空间不匹配”假说认为，工作岗位的郊区化和美国城市中普遍存在的居住隔离是内城少数民族群体失业率较高、收入相对较低和通勤时间较长的重要原因，并将增加内城工作机会、改善内城区与郊区的交通联系等作为消除“空间不匹配”的重要手段。与西方相比，中国的相关研究仍比较薄弱，应在借鉴西方相关研究成果的基础上，形成自己独特的研究视角和分析方法，为解决社会弱势群体就业的空间障碍问题提供参考。 |
| [33] | . This article verifies the hypothesis that a spatial mismatch between jobs and housing exists in two typical low-income housing neighbourhoods, Tangxia and Tongde, in Guangzhou city, where surveys were undertaken. The research shows that the types of residents in Tangxia and Tongde have changed significantly during the past few years. Housing types transferred comprise subsidised rental housing, commercial housing and private lease housing. At the same time, the jobs09“housing mismatch among residents in subsidised rental and commercial houses has become striking. The mechanisms responsible for the mismatch vary from a passive process for residents in subsidised rental housing to an active process for those in commercial housing. In comparison, private lease housing residents do not experience a jobs09“housing mismatch. This result shows that, with the interaction of the legacy of the socialist land and housing market with the new market-orientated system, government still plays an important role in housing supply. This is especially so for low-income families, who face a 0900passive0964 jobs09“housing relocation and mismatch, while the market-orientated parts of the system play an active role in people0964s job09“housing relocation. |
| [34] | . A large national sample from the US 1977 Nationwide Personal Transportation Study is analyzed in order to test the transport economies that may result from the dispersion of work trip-ends. Based on indirect evidence that the largest metropolitan areas have the largest proportion of noncentral-city work trip-ends, we associate a variety of work-trip results for such cities with a polycentric urban form hypothesis. We claim that these results also suggest that decentralized settlement ('sprawl'?) is not necessarily uneconomical. |
| [35] | |
| [36] | . 通过多中心城市空间结构的构建来疏解单中心城市的交通拥挤是城市规划历来的理想,但这种理想正日益受到实证研究的挑战。关于多中心空间结构能否节省通勤距离与通勤时间,存在截然相反的观点。分析表明,两种截然相反的实证结论源于两种不同形成机制的多中心结构,改善交通出行的多中心结构是以就业与居住就地平衡为前提的。 . 通过多中心城市空间结构的构建来疏解单中心城市的交通拥挤是城市规划历来的理想,但这种理想正日益受到实证研究的挑战。关于多中心空间结构能否节省通勤距离与通勤时间,存在截然相反的观点。分析表明,两种截然相反的实证结论源于两种不同形成机制的多中心结构,改善交通出行的多中心结构是以就业与居住就地平衡为前提的。 |
| [37] | . Like many large US metropolitan areas, the San Francisco Bay Area has experienced rapid suburban employment growth since 1980, much of it concentrated in sub-centres. This paper shows that, contrary to the co-location hypothesis, employment decentralisation has not been associated with shorter average commute distances or durations in the Bay Area. Combining statistics on shifts in modal splits and average vehicle occupancy levels reveals that parallelling the region's sub-centring trend has been a substantial increase in average commute vehicle miles travelled (VMT) per employee between 1980 and 1990. The largest increases occurred in the fastest-growing and most remote suburban centres. Using decomposition analysis, we found that increasing commute distances contributed the most to rising commute VMT per employee, and the distance factor had proportionately the greatest effect on rising commute VMT rates in the most peripheral work centres. Since shifts in commute VMT per employee are thought to be strongly associated with transport externalities, we conclude that the social and environmental implications of the Bay Area's regional growth trends deserve more public policy attention than given to date. |
| [38] | . Urban traffic is embedded in and fundamentally shaped by the spatial pattern of urban land use, such as city size, density, extent of polycentricity, and the relationship between employment and residential locations. Previous evidence, mainly from European and American cities, suggests that the duration of commute trips increases with city size and the spatial separation between jobs and housing. On the other hand, the influences of density and polycentricity are less clear. Using data from 164 cities in China, this study empirically analyzes the relationship between city average commute duration and multiple dimensions of urban spatial structure. Controlling for economic, demographic, and infrastructure characteristics, the authors find that commute duration correlates positively with city size and jobs ousing separation but negatively with density and polycentricity. As one of the earliest studies on commute cost in the rapidly urbanizing and motorizing Chinese cities, this study can help Chinese decision makers improve urban economic and environmental efficiency through spatial planning and policy making. Specifically, compact, mixed-use, and polycentric spatial development may ease the burden of commute, and thus substitute for unnecessary infrastructure investment and energy consumption during a period of rapid urban expansion in China. |
| [39] | |
| [40] | . 提 要 国内特 大城 市纷纷采取 多中心空 间战略 来缓 解单 中心蔓延带 来的城 市 问 题 , 但是否有 效却缺乏 系统严谨的检验 " 从 国内外大城市实施 多中心战略的效果来 看, 各方评价褒贬不一, 发达 国家关于多 中心结构能否缓解城市交通拥堵的 实证研 究更是对 多中心理念的绩效提 出了质疑 " 现通过对上海的实证研究来检验 多中心理 念的有效性 , 为我 国特大城市 多中心战略 提供决策依据 " 运用统计方法和问卷调查 数据对上海 中心城 区的分析显示, 就业中 . 提 要 国内特 大城 市纷纷采取 多中心空 间战略 来缓 解单 中心蔓延带 来的城 市 问 题 , 但是否有 效却缺乏 系统严谨的检验 " 从 国内外大城市实施 多中心战略的效果来 看, 各方评价褒贬不一, 发达 国家关于多 中心结构能否缓解城市交通拥堵的 实证研 究更是对 多中心理念的绩效提 出了质疑 " 现通过对上海的实证研究来检验 多中心理 念的有效性 , 为我 国特大城市 多中心战略 提供决策依据 " 运用统计方法和问卷调查 数据对上海 中心城 区的分析显示, 就业中 |
| [41] | . "职住平衡"是城市规划理论和实践中应对交通拥堵和长距离通勤的一项重要规划手段,但在现实中却往往得不到好的效果,"职住分离"的趋势反而愈加明显。从就业机会、通勤成本、住房机会和城市公共服务可达性四个方面可以解释城市职住关系的形成机制,通过北京市2010年家庭大样本出行调查的微观样本对这些机制进行实证验证,分析表明:面对"职住分离",不应将规划凌驾于市场之上,通过主观"设计"居住与产业用地空间配比("堵")的方法来追求理想的"职住平衡"目标,而是需要尊重市场规律,在交通、住房和公共服务等方面为居民提供更多的选择机会("疏"),形成合理的职住关系。 . "职住平衡"是城市规划理论和实践中应对交通拥堵和长距离通勤的一项重要规划手段,但在现实中却往往得不到好的效果,"职住分离"的趋势反而愈加明显。从就业机会、通勤成本、住房机会和城市公共服务可达性四个方面可以解释城市职住关系的形成机制,通过北京市2010年家庭大样本出行调查的微观样本对这些机制进行实证验证,分析表明:面对"职住分离",不应将规划凌驾于市场之上,通过主观"设计"居住与产业用地空间配比("堵")的方法来追求理想的"职住平衡"目标,而是需要尊重市场规律,在交通、住房和公共服务等方面为居民提供更多的选择机会("疏"),形成合理的职住关系。 |
| [42] | . Empirical studies regarding the nexus between urban spatial changes, individual socio-economic characteristics and commuting behaviour are largely conducted in the cities of North American and European developed countries. Studies conducted in fast-growing developing countries are very scarce, particularly in China, the world's second-largest economy. This research presents new evidence on how polycentric development impacts on workers' commuting behaviour in urban China, through a case study of commuting behaviour in four sub-centres in Beijing. The results of this study suggest that polycentric urban development has a significant influence on employees' commuting times, considering the workers' socio-economic characteristics and transport modes. The results of the regression analysis show that local jobs-housing balance at the workplace has a significant impact on individual worker's commuting times. The findings suggest that the location and type of sub-centres are significantly associated with individuals' choice of housing and workplace locations, and accordingly their commuting behaviour. |
| [43] | . Studies of gentrification in London have shown that some groups of middle-class people have been attracted to poor and multi-ethnic areas of inner London in part because of their social and ethnic mix. However, the attraction has often not translated into everyday interaction. In an earlier account of gentrification in Brixton this de facto social segregation was typified as a process of 0900social tectonics0964. In this paper we compare two ethnically and socially mixed neighbourhoods, Peckham and Brixton, that at different times have represented the 0900front line0964 of gentrification in London. We examine the extent to which the gentrification of Brixton in the late 1990s is being mirrored by the gentrification that is occurring today in Peckham 09“ a similarly mixed and counter-cultural area of South London. Whilst we identify continuities between the gentrification process in these two areas separated by a decade of boom and recession, we suggest that the Peckham example demonstrates the need for a more developed approach to the issue of social mixing than that implied by the social tectonics metaphor. Specifically, we argue that there is a need to explain how the presence of classed and ethnic 0900others0964 can be central to the formation of identities within some middle-class fractions in such enclaves in the inner city, and how attitudes and neighbourhood practices can change over time. |
| [44] | . Empirical studies on polycentric urban regions (PURs) tend to analyse their spatial organization by examining only one type of functional linkage between cities. However, it has generally been accepted that urban networks are multiplex phenomena and that spatial interactions between cities can take many different forms, for example, commuting, shopping trips, and inter-firm trade. The spatial organization of each of these functional linkages is not necessarily identical, and, therefore, a region can appear to be polycentric and spatially integrated based on the analysis of one type of functional linkage but monocentric and loosely connected based on the analysis of another type of functional linkage. The aim of this paper is to stimulate further discussion on the multiplexity of urban networks with regard to the relational complexity of urban regions. Focusing on one PUR (Randstad Holland), we compare the geographical scope and spatial structure of different functional networks within it. Our results indicate that the spatial organization of the urban network depends on the lens through which it is assessed. |
| [45] | . We examine spatial patterns and their changes during the 1970s for the Los Angeles region by estimating monocentric and polycentric density functions for employment and population. Downtown Los Angeles is clearly identified as the statistical monocentric center of the region and it is the most consistently strong center in the polycentric patterns. Polycentric models fit statistically better than monocentric models and there was some shift in employment distribution toward a more polycentric pattern. These findings verify the existence of polycentricity in Los Angeles and demonstrate for the first time that employment and especially population follow a polycentric pattern based on exogenously defined employment centers. The results confirm that both employment and population became more dispersed during the 1970s. (EXCERPT) |
| [46] | |
| [47] | . ABSTRACT Current measures of the jobs—housing balance such as jobs—housing ratios and theoretical minimum commutes are conceptually limiting. They fail to capture either multi-dimensional opportunities for possible spatial interaction or differential accessibilities to employment within a realistic commuting framework. A more comprehensive view of spatiality in the jobs—housing balance may be achieved by considering measures of spatial separation, such as those used to study segregation patterns. The purpose of this research is to show how segregation measures may be used to analyse residential—workplace separation. A new index is designed that incorporates spatial interaction concepts from location-based accessibility models. Mathematical properties of the new index are demonstrated along with an analysis that measures the jobs—housing balance. Development of this conceptual and analytical framework bridges previously unblended literatures in segregation indices and the jobs—housing balance. |
| [48] | . 构建了一个基于垄断竞争、规模经济、空间成本、消费者多样化偏好以及商品和服务差异化的大都市多中心空间结构模型,并整合基于agent的建模,借助非均衡(out-of-equilibrium)动态模拟,探讨了人口规模和消费需求、区域间和区域内商业产品及服务的替代弹性、固定成本投入、区位和交通条件等因素的"持续"变化对的大都市空间结构演化的影响过程。模拟表明:以商业为代表的经济活动往往集聚在具有区位优势、规模经济和消费能力的大都市传统中心,而交通条件的持续改善、新兴郊区次中心与传统城市中心之间以及城区内部商业产品和服务的不断差异化对大都市的多中心空间结构有重要影响,但影响的程度不同。更重要的是,大都市的人口规模和消费能力对新兴郊区次中心的形成作用显著。 . 构建了一个基于垄断竞争、规模经济、空间成本、消费者多样化偏好以及商品和服务差异化的大都市多中心空间结构模型,并整合基于agent的建模,借助非均衡(out-of-equilibrium)动态模拟,探讨了人口规模和消费需求、区域间和区域内商业产品及服务的替代弹性、固定成本投入、区位和交通条件等因素的"持续"变化对的大都市空间结构演化的影响过程。模拟表明:以商业为代表的经济活动往往集聚在具有区位优势、规模经济和消费能力的大都市传统中心,而交通条件的持续改善、新兴郊区次中心与传统城市中心之间以及城区内部商业产品和服务的不断差异化对大都市的多中心空间结构有重要影响,但影响的程度不同。更重要的是,大都市的人口规模和消费能力对新兴郊区次中心的形成作用显著。 |
| [49] | . <p>基于第六次人口普查、第二次经济普查和问卷调查数据,定量描述和分析了上海都市区内部以街道为空间尺度的就业可达性及其空间格局,探讨了劳动者的工资收入与居住区位就业可达性的关系。结论表明：上海市的居民就业可达性呈现相对均衡的多中心分布格局,与北京就业可达性单中心的分布格局有明显的不同。同时,在控制个人经济社会属性和地区属性的条件下,上海的居民就业可达性对居民个人收入水平具有显著的正向影响。这一结论的政策含义是,地理区位较差的住房有损于居民收入,可能是吸引力不足的重要原因之一;政府通过提高地区的居民就业可达性,有助于改善就业机会,促进居民个人收入的增加。</p> . <p>基于第六次人口普查、第二次经济普查和问卷调查数据,定量描述和分析了上海都市区内部以街道为空间尺度的就业可达性及其空间格局,探讨了劳动者的工资收入与居住区位就业可达性的关系。结论表明：上海市的居民就业可达性呈现相对均衡的多中心分布格局,与北京就业可达性单中心的分布格局有明显的不同。同时,在控制个人经济社会属性和地区属性的条件下,上海的居民就业可达性对居民个人收入水平具有显著的正向影响。这一结论的政策含义是,地理区位较差的住房有损于居民收入,可能是吸引力不足的重要原因之一;政府通过提高地区的居民就业可达性,有助于改善就业机会,促进居民个人收入的增加。</p> |
| [50] | . 2000年以来北京市持续推进产业结构升级,由此引发了经济活动的空间重构,伴随着住宅郊区化、职住分离以及交通基础设施的配套建设,将引起新一轮城市空间扩展。构建顾及综合可达性因素、邻域因素、自然因素、规划因素以及社会经济因素的城市空间扩展模型,分析诊断北京城区扩展进程中的主要影响因素及问题,从而为指导与管治北京市城市空间的有序扩展提供科学支撑。研究表明:1综合交通静态可达性(单一年份)与城市扩展呈显著负相关;综合交通动态可达性(年份之间的可达性变化)则在引导北京市城市空间发展方面并无显著影响。2邻域建设用地百分比与城市扩展呈正相关,而农用地、林业用地及水域用地的比例将减少土地开发的概率。3城市总体规划在指导城市空间扩展的纲领性地位逐渐受到重视,其对城区扩展的影响程度最为显著。4常住人口的分布现状、第二产业企业数量、第三产业企业数量分布现状对土地开发无显著影响。5认为北京市静态可达性与土地利用变化呈负相关,即可达性条件较差的地区,土地开发的可能性越小,这与北京市"摊大饼式"空间蔓延和居住郊区化的发展现实相符;北京市动态可达性与土地利用变化亦呈负相关,表明可达性提高程度越大的区域并不一定带来更高的土地开发几率,这从侧面传递了沿着既有建成区进行土地扩展的概率远远大于由于诸如轨道交通建设而带来可达性极大改善区域的概率。因此,重视与发挥综合交通动态可达性指标对城市扩展的引导作用,将是有效破解城市蔓延式扩张、优化城市扩展的重要手段。 . 2000年以来北京市持续推进产业结构升级,由此引发了经济活动的空间重构,伴随着住宅郊区化、职住分离以及交通基础设施的配套建设,将引起新一轮城市空间扩展。构建顾及综合可达性因素、邻域因素、自然因素、规划因素以及社会经济因素的城市空间扩展模型,分析诊断北京城区扩展进程中的主要影响因素及问题,从而为指导与管治北京市城市空间的有序扩展提供科学支撑。研究表明:1综合交通静态可达性(单一年份)与城市扩展呈显著负相关;综合交通动态可达性(年份之间的可达性变化)则在引导北京市城市空间发展方面并无显著影响。2邻域建设用地百分比与城市扩展呈正相关,而农用地、林业用地及水域用地的比例将减少土地开发的概率。3城市总体规划在指导城市空间扩展的纲领性地位逐渐受到重视,其对城区扩展的影响程度最为显著。4常住人口的分布现状、第二产业企业数量、第三产业企业数量分布现状对土地开发无显著影响。5认为北京市静态可达性与土地利用变化呈负相关,即可达性条件较差的地区,土地开发的可能性越小,这与北京市"摊大饼式"空间蔓延和居住郊区化的发展现实相符;北京市动态可达性与土地利用变化亦呈负相关,表明可达性提高程度越大的区域并不一定带来更高的土地开发几率,这从侧面传递了沿着既有建成区进行土地扩展的概率远远大于由于诸如轨道交通建设而带来可达性极大改善区域的概率。因此,重视与发挥综合交通动态可达性指标对城市扩展的引导作用,将是有效破解城市蔓延式扩张、优化城市扩展的重要手段。 |
