Chesapeake - Bottleneck Planned?

I looking at the master transportation plan for the previous post, I noticed that Chesapeake actually has a bottleneck planned. Its hard to see from this image but if you click on it and go to page four of the document you can see it better:

Now if you look closely, the Chesapeake Expressway is supposed to be expanded to and 8-lane highway. Then, as it crosses Mount Pleasant, it becomes a 6-lane Highway only to become an 8-lane Arterial after the toll plaza. What's up with this planned bottleneck? If traffic increases as is expected, they would not only need to slow for the toll but then have to merge, causing even greater backup.