1) The population of Ulaanbaatar, Mongolia has rapidly increased, with 41.8% of Mongolia's population living in the capital city in 2013. 2) There has also been rapid growth in vehicle ownership in Ulaanbaatar, with the number of registered vehicles increasing by an average of 15% per year over the last decade. 3) This rapid increase in both population and vehicles in Ulaanbaatar has contributed to worsening traffic congestion and air pollution in the city.