Here are some interchanges I'd enjoy seeing in SimCity 4:
http://www.flickr.com/photos/jnorason/3392323351/
They all involve the RHW and the Roads. Trouble is, they also involve yields and crossing over lanes of traffic. The upper left one involves cars exiting and moving over to the right-hand lane. A real-life example is here:
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Ffarm4.static.flickr.com%2F3452%2F3392329945_750028b4ea_o.png&hash=183c295eb49b08a4ae6a3cbb19cf080e158cfed5)
This is near Easterwood Airport in College Station, Texas.
The one on the bottom (of the example picture) is another entrance for frontage roads. This is much safer (and, likely, easier to make) than the other and is seen here:
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Ffarm4.static.flickr.com%2F3590%2F3392328389_8f4084536c_o.png&hash=b695ed34dbe84052c3ee6e9a3fb23641984e7ed8)
But the exit is now closed (no more two-way road on top). This is at the intersection of SH-6 and Rock Prairie Rd. (College Station, Texas).
They are ideal (nay, perfect) for these types of underpasses made by Chrisadams3997:
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Fimg139.imageshack.us%2Fimg139%2F6830%2Foverpassold2wd2.jpg&hash=ee2fe9965325b7d469f5c4175649e446f4a9b10b)
but that may be attributed to the fact that Chris also lives in College Station.
Anyway,
Are these interchanges possible? I will answer any questions...