It really depends on whether the goal is simply to move people or to also spur reinvestment along the corridor. I won't debate whether or not the second goal is

It really depends on whether the goal is simply to move people or to also spur reinvestment along the corridor. I won't debate whether or not the second goal is valid, but the second goal is why a streetcar can be preferable: * Bus - Super flexible, cheapest, similar capacity to street car. However, because of its inherent flexibility, buses can be rerouted or cancelled. Therefore there is less incentive to invest in the corridor because a customer group can easily vanish. * Buses with dedicated lanes - A good compromise between bus and street car, but drivers sitting in traffic will see the nearly empty bus lanes and complain why the road isn't being used. * Street Car - Cheaper than subway, but because the tracks are laid, it's much less likely to be rerouted or cancelled, creating more incentive to invest in the corridor. * Subway - Most expensive and least likely to be rerouted or cancelled; creates most incentive to invest in the corridor.