Transportation Efficiency Evaluation Considering the Environmental Impact for China's Freight Sector: A Parallel Data Envelopment Analysis

The freight sector is an important component of China's national economy. It is composed of multiple sub-sectors and has a complex internal structure. This internal structure can hide information on the freight sector's operational performance. Previous studies on transportation operational performance made measurements based on the whole transportation sector, and all of these studies ignored the impacts that the internal structure of the sub-sectors have on performance, which leaves a gap in the research. To illustrate this structure, this study proposes a parallel slacks-based measure model to measure transportation efficiency, which can represent the freight sector's operational performance. The efficiencies of transportation operations for the whole freight sector and its three sub-sectors are further measured, by treating the sub-sectors as parallel subunits. Then, the inefficiency sources from the sub-sectors can be identified by the proposed model. To detect the environmental impact on transportation operations, energy consumption and carbon dioxide emissions are also considered in the evaluation. On the basis of the proposed approach, an application of the Chinese freight sector from 2013 to 2017 is provided. The impacts of influential factors on transportation efficiency are also explored. The empirical findings can be illustrated as follows: (1) there exist significant disparities in regional transportation efficiencies in the freight sector and its sub-sectors; (2) the inefficient transportation performance of the Chinese freight sector mainly derives from the poor performance of the waterway sub-sector; and (3) freight volume and population density have positive impacts on the transportation efficiencies of the railway and highway sub-sectors. Finally, some policies for improving transportation efficiency are also provided.