Abstract

This global study simultaneously analyzes how land use differences between cities affect travel time and CO₂ emissions. The land use–travel time–carbon emission relationship in which the time is specified as a mediator is analyzed at the city level on an international scale based on individually reported data by moving away from the tendency of conducting country-level, regional-scale analysis based on estimates from travel survey data or satellite images. A major finding of the structural equation model is that because of the high population density in their high-density built-up areas, compact developments with urban cores reduce travel, and indirectly lessen CO₂ emissions (complete mediation by travel time). In contrast, despite no effect on travel, gross population density in the entire city is found to have a direct effect in reducing per-capita emissions based partially on the economies of scale. The proportion of the low-density built-up area in the city also directly reduces the emissions, which might reinforce the concept of the paradox of intensification. Among the control variables, household size, fuel price, and congestion level may ultimately lead to less CO₂ emissions because their direct effects, which are positive on travel time, would be overwhelmed by the negative effects on CO₂ emissions.

摘要

这项全球研究同时分析了城市之间的土地利用差异如何影响旅行时间和 CO ₂排放。摆脱了国家层面、区域尺度分析的趋势，以个体报告数据为基础，在国际尺度上分析了以时间为中介的土地利用-出行时间-碳排放关系基于旅行调查数据或卫星图像的估计。结构方程模型的一个主要发现是，由于高密度建成区的人口密度高，城市核心的紧凑型开发减少了出行，并间接减少了 CO ₂排放（按行程时间完全调解）。相比之下，尽管对旅行没有影响，但发现整个城市的总人口密度对减少人均排放量有直接影响，部分基于规模经济。城市中低密度建成区的比例也直接减少了排放，这可能会强化集约化悖论的概念。在控制变量中，家庭规模、燃料价格和拥堵程度最终可能导致更少的 CO ₂排放，因为它们对旅行时间的直接影响将被对 CO ₂排放的负面影响所压倒。