we have that option on the ground they are called busses. the only problem is theres no main bus station in the city to fix the long line of busses in the city. the new light rail may fix some problems but it's going to take less time than a monorail system.
Good luck getting the same extra capacity, speed and reliability out of buses when there's only a max of 58 people per bus and you have traffic, road speed limits, etc to contend with.
Monorails and light rail also have similar construction times. It's the heavy rail and freeway options that tend to take forever.