BRT systems. The study concludes, that BRT-„capacity on TransMilenio exceeds all but the highest capacity HRT systems, and it far exceeds the highest LRT system.“ Performance data of 84 systems show 37,700 passengers in peak hour per direction (PPHPD) in the best BRT system 36,000 in the best 1-track-HRT system 13,400 in the best LRT system More topical are these BRT data 45,000 PPHPD in a 1-lane-system using articulated buses (2020 in Istanbul) 320 busses per hour per direction in the corridor Nossa Senhora de Copacabana in Rio de Janeiro for the year 2014 meaning a bus every 11 seconds. 65,400 PPHPD in 600 buses in the corridor Presidente Vargas in Rio de Janeiro for the years 2012 resp. 2014, which means 10 buses per minute or a bus every 6 seconds. Comparison with light rail After the first BRT system opened in 1971, cities were slow to adopt BRT because they believed that the capacity of BRT was limited to about 12,000 passengers per hour traveling in a given direction during peak demand. While this is a capacity rarely needed in the US (12,000 is more typical as a total daily ridership), in the developing world this capacity constraint (or rumor of a capacity constraint) was a significant argument in favor of heavy rail metro investments in some venues. When TransMilenio opened in 2000, it changed the paradigm by giving buses a passing lane at each station stop and introducing express services within the BRT infrastructure. These innovations increased the maximum achieved capacity of a BRT system to 35,000 passengers per hour. The single-lane roads of Istanbul Metrobus had been frequently blocked by Phileas buses breaking down, causing delays for all the buses in a single direction. After focusing on Mercedes-Benz buses, capacity increased to 45,000 pph. Light rail, by comparison, has reported passenger capacities between 3,500pph (mainly street running) to 19,000pph (fully Grade-separated). There are conditions that favor light over BRT, but they are fairly narrow. To meet these conditions you would need a corridor with only one available lane in each direction, more than 16,000 passengers per direction per hour but less than 20,000, and a long block length, because the train cannot block intersections. These conditions are rare, but in that specific instance, light rail might have a minimal operational advantage. The US General Accounting Office GAO summarized in the report "MASS TRANSIT - Bus Rapid