The use of rail transits results in the generation of a large amount of carbon emissions. Throughout the life cycle of a rail transit system, huge amounts of carbon are emitted, which contributes to the threat posed by carbon emission on the city ecosystem. Despite the many methods previously proposed to quantify carbon emissions from rail transit systems, a method that can be applied to measure carbon emissions of monorail systems is yet to be developed. We have used the life cycle assessment (LCA) method to propose a method that can be used to quantify carbon emissions from monorail transits. The life cycle of a monorail transit system was divided into four stages (production, construction, use, and end-of-life). A monorail transit line segment in Chongqing, China, was selected for a case study. The results show that the “use” stage of the monorail transit line system significantly increases (93.2%) carbon emissions, while the “end-of-life” stage does not contribute significantly to the total carbon emitted. The processes of generation of steal, concrete, and cement are the three leading processes that contribute to the emission of carbon dioxide. The percentages of carbon emitted during these processes are 32%, 29.6%, and 13.3%, respectively. Prestressed concrete activity accounts for the largest proportion (91.1%) of the total carbon emissions. The results presented herein can potentially help in realizing sustainable development and developing green transportation.

The present paper investigates the relationship between pressure (bond stress) and displacement at the failure load for different materials through testing and modeling. First, single-end tests were conducted on prebonded stressed and perforated concrete specimens with corrugated plastic, metal, and rubber extractive pipes. These tests reveal that corrugated plastic pipes provide good bonding performance with concrete and grout. Hence, they can be applied in the hole-forming process of posttensioned prestressed bonded structures, along with corrugated metal pipes and rubber extractive pipes. Based on the experimental observations and results, a theoretical approach for applying corrugated plastic pipes in projects such as China’s high-speed rail has finally been demonstrated.

Despite the widespread use of plastic bellows in prestressed channels, their poor bonding with concrete and mortar results in “layering,” which limits their application in practical engineering. In this study, the bonding property between plastic bellows and concrete or grout material was investigated using a single-end compression test on plastic bellow concrete. The slip failure mode, ultimate load, and slip of plastic bellows were obtained. Furthermore, the analysis of the bond-slip properties of plastic bellows indicated that the bond strength decreased with increasing bond length. Moreover, the increase in the loading force was greater than the increase in the contact area. Based on the test data, a bond-slip constitutive relationship model was established, which accurately reflects the bond-slip process. The expressions of bond and slip were derived along with different bond positions of plastic bellow concrete specimens. Finally, a three-dimensional finite element model of a plastic bellow concrete specimen was established. The numerical simulation curve was compared with the experimental and fitting curves. The results indicated that the bond strength of the plastic bellow concrete specimen decreased with increasing bond length. The influence of bond strength on the contact area was comprehensively analyzed. This study effectively combines experimental research, theoretical analysis, and numerical simulation to analyze the bond performance between plastic bellows and concrete or grout material.