I don't think a six-lane boulevard through a park ties together the west and east sides of downtown, but maybe that's just me.

I understand why you'd think that, and I used to think the same, but if you look at Klyde Warren Park in Dallas you'll see that it can actually be very successful. KWP is a small park built on top of a recessed highway and has 3-lane roads on each side of it.

Before KWP, the area had a few office buildings and hardly any residential, and almost nobody hung out there after 5pm. The highway was seen as a divider between the desirable areas of Uptown and the dirty, "don't go here after dark" areas of downtown.

After KWP, both Uptown and Downtown have seen massive growth, and specifically the area right around the park has developers fighting over land, and in just ~4 years theres already 10+ new skyscrapers that have gone up.

It would be better still without the 6-lane roads cutting through it, but I think those roads are necessary and the park can be successful with them.