COLOMBIA. Bogota. 2013. Transmilenio bus. Transmilenios is a new Rapid clean air Bus System. TransMilenio consists of several interconnecting BRT lines, each composed of numerous elevated stations in the center of a main avenue, or "troncal". Passengers typically reach the stations via a bridge over the street. Usually, four lanes down the center of the street are dedicated to bus traffic. The system has become overcrowded and thousands of private illegal bus lines still clog up traffic and creat serious contamination in the city