城市客运交通工具碳排放效率差异——以襄阳市为例

为准确测度城市客运工具碳排放效率的差异，探寻多元出行和碳减排双赢的改进路径，本文构建涵盖车辆存量、道路、土地、能源及环境 5 大要素体系，利用三阶段超效率 SBM-DEA (Slacks-Based Measure)模型和SFA(Stochastic Frontier Approach)方法，测度城市客运工具碳排放效率，并厘清政策和外生环境因素对投入要素冗余的影响；构建效率贡献度和边际效应模型分析投入产出要素的效率贡献度及其边际效应。基于襄阳市的案例表明：7种客运工具的碳排放效率呈传统公共交通(含巡游车)大于共享交通大于私人交通的差异化态势；外生环境因素中，优化能源结构能显著减少能源资源的多余消耗，交通工具的便捷性对消除多余投入具有显著积极作 用。效率贡献度结果反映碳排放效率提升路径的异质性：车辆规模过剩是制约共享交通碳排放效率的主要原因，规模每减少10%，效率分别提高12.0%(网约车)和19.8%(共享电踏车)。清洁能源发展对私家车碳排放效率的提升作用较大，清洁比例每增加10%，碳排放效率平均提高8.9%。 在现阶段公交优先发展水平下，公交车平均运行速度每增加1 km?h-1 ，碳排放效率提高0.201。 并从技术和管理两方面提出改善碳排放效率的建议和措施。

Urban Passenger Transportation Mode Carbon Emission Efficiency Difference: A Case Study of Xiangyang City

To accurately measure the difference of carbon emission efficiency of urban passenger transportation modes and explore the improvement possibility of multi-mobility and carbon emission reduction, this paper proposes an index framework considering vehicle stock, road, land, energy, and environment. The three-stage super-efficient SlacksBased Measure (SBM) and Stochastic Frontier Approach (SFA) are used to measure the carbon emission efficiency and clarify the influence of policy and exogenous environmental factors on the redundancy of input factors. This paper also develops an efficiency contribution model and a marginal effect model to analyze the efficiency contribution of input and output factors and their marginal effects. The case study of Xiangyang City indicates that: The carbon emission efficiency of seven modes of passenger transportation is different, such as traditional public transportation mode (including cruisers) shows higher efficiency than shared transportation which is more efficient than private transportation. Among the exogenous environmental factors, optimization of energy structure can significantly reduce the redundant consumption of energy resources, and the convenience of transportation has a significant positive effect on the elimination of redundant inputs. The efficiency contribution results reflect the heterogeneity of carbon emission efficiency improvement paths: excess vehicle size is the main constraint on carbon emission efficiency of shared transportation, with each 10% reduction in size, the efficiency increase by 12.0% for ride-hailing and increase by 19.8% for shared electric bicycles. The promotion of clean energy plays an important role on improving the carbon emission efficiency of private vehicles. Every 10% increase in clean ratio, there will be an average increase of 8.9% of car emission efficiency. At the current level of bus priority development, the carbon emission efficiency will increase by 0.201 for every 1 km?h-1 increase in the average bus operating speed. The paper also proposes the suggestions andmeasures to improve carbon emission efficiency from technical and management aspects