Hello,

I just modeled an isolated intersection as two-lane roundabout.

At first I had some issues, some of which are kind of resolved now.

Why, though, can I not have two lanes entering and two lanes exiting on all four legs?
If I set 2 lane exits for all four legs, I am not able to maintain 2-lane movements straight thru the intersection.

More important, however, is another problem:
One leg shows intersection paths from both the lanes going into the two exit lanes of the right turn. During simulation, however, only the right lane is used. And I really need the two lanes.
Since it's an isolated intersection, there can't be any impact of lane changes or something like that...

Does anybody has an idea what might be causing this behavior? That would help me out a lot here!

Thanks in advance,
Stephan

Hi Stephan,

Consider an east-west roadway that passes through a two-lane roundabout. Let's also consider the EB direction. Assume you have set a two-lane exit for EB vehicles. These EB vehicles will be able to exit the roundabout from the center and outside lanes.

However, this impacts the NB direction. Vehicles entering from the rightmost NB lane will not be able to proceed through. In SimTraffic, the fact that EB through vehicles can exit from the inside lane creates a conflict point for NB vehicles in the outside lane. This is not allowed so the NB vehicles in the outside lane will exit and head east.

So, two lane exits work Ok in two directions. But there will be issues when this is setup for all directions. This is being looked at for future models.

Thanks,

John.