>>1972577>it can't go really fast and have high maintenance cost. The weels and the rail are worn out rather quick.This really depends on the type of monorail. A suspended monorail with a single track and metal wheels will do just as well as a train.
Grade separation is a big plus, since you can run a tight schedule, and are almost immune to crashes with road vehicles. Thus the carriages can be much lighter, which comes with it's own benefits.
Another benefit of grade separation is that the area below remains usable.
>>1972577>can't go really fastThe Wuppertal monorail can do 60 km/h which is decent for inner city.
Straddle beam monorail like the Las Vegas monorail can do 80 km/h.
Transrapid can do 300+ km/h.
This is all 70's and 80's technology by the way.
