Bus routes
I have several bus routes because you can drive buses where trains would not be realistic.
First of all driveable buses are really trains in disguise so you need to lay down invisible track on top of the road, so the type of road you
use is not relevant. For the invisible track, I use (all by cyberstorm):
busroutew - a two lane bus route spaced so it matches the outer lanes of a 4-lane street
busroute2 - a two lane bus route spaced so it matches a two lane street or road
busroute1 - a one lane bus route used for one way streets, to connect the wide bus route to the narrower bus route where a road narrows or
widens, for making 90 degree turns with having to use splines since they snap to the 2 lane routes, also for bus turnarounds, and to connect the other two bus routes to the bus stop.
The great thing about cyberstorm's bus routes is that if you see green, the level is just right, if you see red, it's too high, and if you see nothing, it's too low in relation to the road. As with all invisible track, you only see it in Surveyor.
Now you need an passenger-enabled invisible station for the bus stop with a very short platform, so I use AJS Station 1x50sQ by andi06. Use the single lane bus route to connect the station to the two lane bus routes. Then, to provide a bus shelter, I use City_2000_Shelter by ggotti, or you can use Modern Shelter Small Narrow by marky7890.
Finally, for the driveable bus, I use Swiss Post Bus, also by cyberstorm, but there are a few others on the DLS.
On level ground its fairly easy to build bus routes, but on slopes you have to match up the spline points and their elevation for both the road and the bus route. On tight curves, lay down the 2 lane bus route first since if the curve is too tight the bus route lanes will be too close together.
Assigning the bus to a driver in Edit Session and where to stop is exactly the same process as for trains. Of course, since the bus route is on the road, the cars on the road drive right through the buses, or vice versa. If this bothers you, you could use roads with no car traffic but that's not realistic either.
I have a bus route on a 2-lane rural road which takes skiers from a bus stop adjacent to the light rail transit station in the nearest town up into the mountains, across bridges, through the trees, and finally to another bus stop at the ski resort itself. Challenging to do - start with level bus routes first.
