A principal criticism of BRT systems is that they may not accomplish their promise of an efficient, rapid flow of passengers along their dedicated bus lanes. The unpopularity of Delhi's BRT and the increasing riots and spontaneous user demonstrations in Bogotá raise doubts about the ability of BRTs to tackle issues such as the traffic jams induced by dedicated lanes. Overcrowded stations and BRT vehicles may fail to keep pace with increased ridership, and may eventually need to be replaced with high-capacity rail systems.