面对全球气候变暖的严峻挑战，实现低碳发展已经在国际社会达成共识。城市是人类经济活动最密集和最活跃的区域，在创造巨额社会财富的同时，也是碳排放的主要区域。联合国环境规划署研究显示，城市占地球表面积的3%，但创造全球财富的80%，消耗世界能源的2/3，也排放了全球温室气体的70%。因此，城市将是人类可持续发展的主战场，低碳城市建设对于应对全球气候变化具有至关重要的意义。交通是城市的“血脉”，城市交通是石油等化石能源消耗量增长最快的部门，占城市能源消耗的30%-40%，交通碳排放约占城市总量的30%，因而交通低碳发展是建设低碳城市的重要领域和突破口。作为“低碳城市试点”和“低碳交通运输体系建设城市试点”，北京市面临着巨大的交通需求增长压力、不尽如人意的交通结构，以及高油品依赖高排放低效率的城市交通现状，城市交通低碳发展对北京市低碳城市建设意义重大。因此，对城市交通低碳发展的研究将丰富低碳交通、低碳城市的理论研究，可为北京市实践提供一定的参考、为同类型城市的交通发展提供借鉴。

本文以北京市为研究区域，研究城市交通低碳发展问题。在总体核算北京市城市交通碳排放量、掌握碳排放时空特征的基础上，根据对城市交通碳排放影响因素层次划分的结果，平行进行了城市发展影响交通碳排放的实证检验、城市交通活动低碳优化情景分析以及居民出行低碳选择行为分析，最终总结提炼了实现北京市城市交通低碳发展的路径。

通过研究本文认为：首先，北京市市域交通碳排放二十年间增长了近5倍，城市客运交通碳排放量中88%来源于油品燃料，私人交通贡献比例为76%。城市交通碳排放的时空特征表现为：总量和人均量都达到相对稳定的阶段，碳排放经济强度不断下降；能源结构中油品依赖过高，交通结构中私人交通和准公共交通占比大、效率低；居民出行碳排放表现出城市中心向边缘的递增趋势性，并存在空间集聚特征。北京市城市交通低碳发展影响因素可以划分为城市发展驱动、交通活动产生和居民出行决定三个层次。其次，北京市城市发展带来了人口、经济和空间等要素的规模扩张和结构演进，驱动了交通碳排放；城市化进程推进对碳排放变化的影响最为显著，人均GDP对排放增长的贡献度最大；北京市城市交通碳排放增速高于城市规模扩张速度，呈现超线性粗放关系；北京市城市建成环境特别是城市功能影响居民出行碳排放分异性，证明了密度、城市功能、道路设计和公共交通临近度对出行碳排放存在影响。再次，在北京市城市交通活动低碳优化的三类方案中，交通能源转型效果最为显著，转型方案中节能技术最优、电气化次之；交通结构优化效果较好，优化方案中公共交通发展最优，私人交通和准公共交通扩张为负效果，发展轨道交通和慢行交通可以进一步提高减排效果；交通活动水平调控可以在一定程度上降低交通碳排放的增速；未来一段时间内，低碳优化的难点依然是控制私人乘用车分担率和替代油品燃料。第四，北京市居民通勤出行低碳选择是根据认知特征、人口社会学特征等自身属性，在通勤成本和出行引导政策所构成的选择情景中形成的；受行为态度、主观规范、知觉行为控制影响的低碳通勤意愿，居民的私人乘用车保有和家庭规模，通勤时间成本，经济补贴和限制私人乘用车等政策，都显著影响着居民低碳通勤选择；另外，居民低碳引导补贴定价在受教育水平和出行时间成本的影响下，大致为减少每千克碳排放补贴2.14-2.22元。最后，针对发展模式低碳选择、交通活动低碳优化和居民出行低碳引导三个层次设计北京市城市交通低碳发展方案，在宏观城市建设、中观交通运营管理和微观居民引导三个层面，通过“城市交通供需低碳管理”、“城市交通低碳发展信息化建设”和“提高城市交通低碳治理效率”三项综合路径，实现北京市城市交通的低碳发展。

本研究的创新点为：一是发现了北京市居民出行碳排放呈现城市中心向边缘的递增趋势，验证了建成环境特别是城市功能对居民出行碳排放空间分异性的影响，为城市建成环境低碳改造提供了依据；二是得到了准公共交通分担率反向作用于城市交通低碳发展，应谨慎控制规模；证明了慢行交通促进低碳发展，应予以重点发展；为交通活动低碳优化提供了策略。三是得到了居民出行低碳选择受认知特征影响，居民认为低碳通勤最大的益处是减少拥堵，节能减排次之；时间成本高、设施不便利阻碍低碳通勤；家人等关系亲近群体对居民低碳通勤意愿影响明显；为居民出行低碳引导提供了思路。

Confronted with the severe challenge of global warming, the international community has reached a consensus to achieve low-carbon development. As the most intensive and active area of human economic activities, cities are not only creating prodigious social wealth, but also the primary area of GHG(Greenhouse Gas, GHG) emissions. Research indicates that cities, accounting for 3% of the earth's surface area, contribute to 80% of global wealth. However, 2/3 of the world's energy consumption and 70% of global GHG emissions also stem from cities. For this reason, cities are doomed to be the chief battlefront of human sustainable development, and the construction of low-carbon cities brings significance to combat with global climate change. Transportation is the "artery" of cities. As the fastest growing sector of fossil energy consumption, such as oil, urban transportation triggers 30%-40% of the city's energy consumption. In addition, transportation leads to 30% of the total urban GHG emissions approximately. Therefore, the development of low-carbon transportation is a breakthrough field in the construction of low-carbon cities. Under the current situation of increasing transportation demand, unsatisfactory traffic structure, travelers' high dependence on high oil products and high GHG emission and low efficiency of urban transportation, Beijing, as a "low-carbon city pilot" and "low-carbon transportation system construction city pilot", is crucial to realize low-carbon transportation. The findings on low-carbon development of urban transportation in Beijing enriches the theoretical research on low-carbon transportation and low-carbon city. Moreover, it can also provide reference and guidance for the low-carbon development experiment in Beijing and provide experience and for other cities.

This thesis focuses on the low-carbon development of urban transportation in Beijing. Based on the overall accounting of carbon dioxide emissions of urban transportation in Beijing and the analysis of the scale, structure and time-space characteristics of carbon emissions, the diversified factors affecting low-carbon transportation are studied. Next, according to diversified factors, this paper pays close attention to the impact of urban development on transportation carbon emissions, the low-carbon optimization scenario of urban transportation activities and the low-carbon choice behavior of residents' travel. Finally, paths to achieve the low-carbon development in Beijing are figured out.

The findings of the thesis are as follows. Firstly, the carbon dioxide emission of Beijing's transportation has increased nearly 6 times in 20 years. 88% of the carbon emission of urban passenger transportation comes from oil fuel, and 65% from private transportation. Meanwhile, there are multiple temporal and spatial characteristics of transportation carbon dioxide emissions, for instance, the total emissions and per capita level have reached a relatively stable stage, and the economic intensity of emissions has been declining. The energy structure is irrational, the oil dependence is too high, the proportion of private transportation and paratransit is considerable but inefficient. The carbon dioxide emission of residents' travel represents an increasing trend from center to edge and spatial agglomeration. The development of low-carbon transportation in Beijing is mainly influenced by the driving force of urban development, the generation of transportation activities and the decision-making of residents' travel. Secondly, urban development in Beijing has brought population, economic and spatial scale expansion and structural evolution, driving transportation carbon dioxide emissions. Urbanization has the most significant impact on emissions change, and per capita GDP has the largest contribution to emissions growth. Additionally, the growth rate of urban traffic carbon dioxide emission is higher than that of urban scale expansion, displaying a super linear extensive relationship. The built environment inside the Sixth Ring Road, especially its urban functions, affects the spatial differentiation of resident travel carbon dioxide emissions. Results shows that the density, city function, road design and public transport proximity affects carbon dioxide emissions of resident travel. Thirdly, among the three schemes of low-carbon optimization of urban transportation activities, the effect of transportation energy transformation is the most significant, in which the energy-saving technology is the best, the electrification is the second, and the effect of natural gas transformation is not significant; the effect of transportation structure optimization is optimistic, in which the development of public transportation is the best, private transportation and paratransit are the negative; the regulation of traffic activity level can reduce the growth rate of transportation carbon dioxide emission to some extent. In the future, the difficulty of low-carbon optimization is still to control the share rate of private passenger vehicles and to supersede oil fuels. Fourthly, the residents' low-carbon travel choice in Beijing is based on the cognitive characteristics, demographic and sociological characteristics of their own attributes, and formed in the choice scenario composed of commuting costs and travel guidance policies. In detail, the low-carbon commuting intention influenced by attitude towards the behavior, subject norms and perceived behavior control, the ownership of private passenger cars, family size, commuting time cost, economic subsidies and restrictions on private passenger cars and other policies significantly affect the low-carbon commuting choice of residents. Besides, the pricing of low-carbon guidance subsidy is affected by education level and travel time cost, and the subsidy standard for reducing carbon emissions is 2.14-2.22 yuan per kilogram. Finally, according to the three levels of low-carbon development mode, low-carbon optimization of transportation activities and low-carbon guidance of residents' travel, the low-carbon development plan of Beijing urban transportation is designed. At the three levels of macro urban construction, meso transportation operation management and micro resident guidance, the three comprehensive paths of "low carbon management of urban transportation supply and demand", "informatization construction of urban transportation low carbon development" and "improving the efficiency of urban transportation low carbon governance" are promoted to realize the low carbon development of urban transportation in Beijing.

The innovation points of the thesis are as follows. Firstly, the increasing trend of Beijing residents' travel carbon dioxide emission from the center to the edge of the city is obtained, which verifies the impact of the built environment, especially the urban function, on the spatial differentiation of residents' travel carbon dioxide emission, and provides a basis for the low-carbon transformation of the urban built environment. Secondly, it is found that the growth of urban transportation carbon dioxide emission and the expansion of urban scale in Beijing have a super linear extensive relationship. In the past decade, the relationship between transportation carbon dioxide emission and population and economic scale has shifted to sublinear, but the relationship between transportation carbon dioxide emission and spatial scale has deteriorated to superlinear extensive, which provides a direction for low-carbon control of urban development scale. Thirdly, the thesis demonstrates that the paratransit share rate plays a reverse role in the low-carbon development of urban transportation, and the scale should be carefully controlled. Meanwhile, non-motorized traffic promotes low-carbon development, which should be focused on. The findings above is conducive to the low-carbon optimization of transportation activities. Finally, it is found that the cognitive characteristics play a part in the choice of low-carbon travel. Residents believe that the biggest benefit of low-carbon commuting is to reduce congestion, followed by energy conservation and emission reduction. While, high time cost and inconvenient facilities hinder low-carbon commuting. Family and other close groups have significant influence on residents' low-carbon commuting willingness. The conclusions above will shed some light on the low-carbon guidance of residents' travel.