Conclusion

The increase of transportation CO2 emissions in Chinese and Indian cities in the future will significantly impact the global climate change. By 2030, the total CO2 emissions from major travel modes (electric motors, buses, and cars) in major Chinese cites (Beijing, Shanghai, Shenzhen, and Guangzhou excluded) will reach 480 × 106 t. The annual average CO2 emis-sions per person will be increased to 1.6 t in 2030 from 0.22 t in 2012. It is estimated that the total CO2 emissions from the above three travel modes in major China and India cities will be increased from 135 × 106 t in 2012 (0.37 % of the total global CO2 emissions) to 961 × 106 t in 2030 (2.67 % of the total global CO2 emissions), which will affect the global climate change significantly. Hence, to mitigate global change, it is important to explore the characters of the commuting trips and to find strategies to reduce commuting CO2 emissions in China and India.

From the analysis in this paper, several common characteristics in both Xi’an and Bangalore can be found, including (1) both cities are under fast urbanization and quick motorization; (2) the residents have good education level; (3) a high percentage of commuters work in private companies; (4) a high percentage of commuters own houses/apartments; (5)

both cities sprawl by radial and ring roads and leading industries are located outside or along the 2nd Ring Road in Xi’an and Outer Ring Road in Bangalore; (6) traffic congestions exist in central areas of the city; (7) commuters with car availability, high income, or living in the outer areas/along the ring roads are high CO2 emitters and a small percent of commuters produce the majority of the CO2 emissions; and (8) the vehicle occupancy and traffic congestion have large impacts on reducing CO2 emissions. It is found that the changes on vehicle occupancy of car, normal coach, taxi, and bus could reduce CO2 emissions by as much as 20 to 50 % or increase CO2 emissions by as much as 33.33 to 66.67 %, and the changes on traffic congestions could reduce or increase CO2 emissions by as much as 11 to 15 %. The differences between the two cities include (1) Xi’an has higher population density and compact urban form; (2) the sprawl in the outer areas of Bangalore is large, haphazard, and unplanned; (3) the household income, car ownership rate, commuting by car, and commuting share of public transport in Xi’an are higher than those in Bangalore; (4) the average commuting distance in Xi’an is shorter than that in Bangalore; (5) the average individual or household CO2 emissions in Xi’an are lower than those in Bangalore; and (6) Bangalore has more household members (averagely 4.53 per person in one household) and a higher two-wheeler ownership rate (55.4 %).

The reasons of these findings are (1) better road conditions, longer commuting distance in the outer areas, and weak public transport service have caused more car uses and high CO2 emissions in both cities; (2) Bangalore’s lower density and more dispersed urban growth has caused even longer commuting distances, poor transit service, prevalence of the two-wheelers fueled by gasoline, and thus higher emissions than those in Xi’an; and (3) the buses and taxis driven by CNG and metro and electric motors driven by electricity also helped in reducing the transportation CO2 emissions in Xi’an.

A number of countermeasures can be proposed from this study for the global low-carbon transportation development and climate change mitigation. Firstly, it is important for Chinese and Indian cities, especially for Chinese cities, to focus on reducing the commuting CO2 emissions and controlling the potential increase of commuting CO2 emissions produced by the high emitters and individuals located in the outer areas, with car availability, or high income during the rapid economic growth, urbanization, and motorization, and to provide the substi-tute travel modes for self-driving. Secondly, the keys to reduce the commuting CO2 emissions in Chinese and Indian cities are increasing vehicle occupancy, ensuring the priority of public transit and its outstanding service, controlling the car uses, and implementing parking demand management in the area of the industry zone. Furthermore important, in the early stage of the land development in Chinese and Indian cities, investment in public transit must be guaranteed to support TOD. Thirdly, radial rail transit and rapid bus routes in the inner-outer directions should be developed with outstanding service levels so that high emitters with car availability, high income, and living in the outer areas will use public transit instead of car for commuting. Fourthly, Indian cities need more compact and high-density urban development patterns to reduce the travel distance. Fifthly, the use of clean energy vehicles can also help in reducing the transportation CO2 emissions in Chinese and Indian cities. These strategies are significant for reducing CO2 emissions in Chinese and Indian cities and other similar cities in the developing countries. Thus, they are important for the global climate change mitigations.