Have an intersection at the edge of a system that I'm having trouble trying to get it to operate realistically. The problem leg has a through and a through/right lane, and trouble is it appears that the majority of the traffic ends up in the through/right lane, which queues traffic up beyond the edge of the model. The following intersection has a high RT volume (50%), but in the field anyone who wants to continue through on the road uses the dedicated Through lane with the through/right lane becoming a defacto advanced turn lane for everyone that turns right at the following intersection.

I’ve tried playing with the Mandatory and Positioning distances on the legs at the intersections in question, but haven’t seen much of a change (up to the point where it broke the model). I’m also reticent about changing driver behavior for the entire (large) model, as this is the only trouble spot. Are there any other factors that I’m not aware of that could impact this? Or a work around to get the behavior we want (even lane usage)? Thanks.

Hi NFOtte,

First, I'd suggest going to Options>Map-Settings in Synchro. Check the box to show Intersection Paths. Do these lanes align downstream as you expect? If not, use the Lane Alignment in the Simulation Options to adjust these. You can see details on this in Chapter 9 of the User Guide (page 9-2 to 9-4).

Regarding the Mandatory and Positioning distances, you really don't change these at the intersection. Change them at the node that is causing the lane changes. For instance, if you have a lane drop (via bend), change the distances on the bend. These distances extend from the node you are changing upstream (and beyond upstream nodes). Figure 24-7 is an illustration (even thought it doesn't show the distances beyond the signal).

Details on these settings are found on pages 9-8 & 9 with additional info starting on page 24-8. Finding the "correct" values for your situation is a bit of trial and error.

Thanks,

John.