That extra space has a purpose and will still be needed with this thing installed. Gutters are not just there for drainage; they also serve as a space buffer b

That extra space has a purpose and will still be needed with this thing installed. Gutters are not just there for drainage; they also serve as a space buffer between sidewalks and the road in places that don't have swales for separation. Shoulders are there for parking and getting broken-down vehicles out of travel lanes. Bike lanes are for, well, bikes. You lose those functions if you want to install this and not replace the thing you removed. As for the ground area it needs, it appears that the rails are roughly the width of a suburban sidewalk[1]. Add guard rails to keep people and vehicles from interfering with it and you have close to half a travel lane on each side consumed by this. What then is the advantage to this versus taking a travel-lane's width for a tram or installing an elevated people mover? [1] http://www.borntoengineer.com/china-unveils-prototype-straddling-bus/#howitworks http://www.borntoengineer.com/china-unveils-prototype-stradd...