I’m guessing its this from the wiki.
Do not directly connect approaching with departing roads.
Roundabout with correct connections
Each way which intersects with the roundabout should be connected to it with a separate node. Two ways which enter and exit a roundabout should never connect to the same node on the roundabout. This is required to allow routing applications and software to provide correct directions, otherwise the routing software will not correctly recognise the roundabout. With a segment of the roundabout between the entrance and exit, routers can safely recognise that a section of the roundabout has to be driven through.
Which routing software? 
Anway, if this is the background of the roulette I guess its fair enough.