 Existing plans to improve transportation include a subway system, several major road projects such as a highway to link Ulaanbaatar to the regions of Altanbulag and Zamyn Uud, plans to upgrade existing regional airports and roadways, and Mongolian Railway projects that will connect cities and mines.The national and municipal governments regulate a system of private transit providers which operate bus lines around the city.There is also an Ulaanbaatar trolleybus system.