wiki on BRT:

As this will probably fall afoul of wikipedia's ban on primary research, thought it was worth repeating:

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.^[44] Light rail, by comparison, has reported passenger capacities between 3,500pph (mainly street running) to 19,000pph (fully Grade-separated). "From these findings … there is little evidence to support the view that [light rail] can carry more than busways.".^[45] 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 would have a significant operational advantage. However, "... any perceived advantages of [light rail] over BRT are primarily aesthetic and political rather than technical … due to the perceived capacity constraint of BRT there are currently no cases in the US where [light rail] should be favored over BRT."^[46]

 44) W. Hook, S. Lotshaw and A. Weinstock (2013). "More Development For Your Transit Dollar. An Analysis of 21 North American Transit Corridors" (PDF). Institute for Transportation and Development Policy. p. 20.

 46) W. Hook, S. Lotshaw and A. Weinstock (2013). "More Development For Your Transit Dollar. An Analysis of 21 North American Transit Corridors" (PDF). Institute for Transportation and Development Policy. p. 21.