Environmental impacts of inner-city rail systems: Example of Ankara Çayyolu subway

The share of transportation sector, which is the leading factor in terms of climate change, in the CO2 emission is 24% across the world, and in consumed energy, it is 36% and on the steady increase. About 90% of urban transportation in Turkey is provided by land. The heavy increase in the usage of rubber-wheeled vehicles brings along many problems. Building new roads in fields where demand for travelling is on the rise cause increase in vehicle traffic. Thus, journey time extends and depending on stop-and-go carbon dioxide emission and energy consumption increase further. In order to solve this problem, new roads and stack interchanges are built, yet same problems arise repeatedly. Methodology is developed through typical journey distribution, CO2 emission and energy consumption factors. Methodology is applied on Çayyolu and EGO bus routes along with Çayyolu subway. According to results, the impact of inner-city rail system on environmental quality and energy consumption is determined before and after subway usage. Our findings show that opening of Çayyolu subway in 2014 and the integration of subway with EGO bus lines in the zone decrease the environmental damage arising from rubber-wheeled vehicles. Within the study, three scenarios have been developed in order to present the impact of increase of rail system in the share of typical travelling distribution on environmental pollution due to transportation as well as decrease in traffic jam and journey time. In order to avert environmental damages due to transportation, solution recommendations for enhancing railway system usage are offered.