I have to give Colorado a lot of credit! As I've looked up roads you've mentioned in this thread (SR-93, Foothills, etc.) .... the state does road planning right:
They build a road and leave plenty of room for future grade separation --- so it's easy to add later as demand grows and funding is available. Utah built this horrible highway (Bangeter) through the heart of Salt Lake County. They left NO room for future grade separation. Today the demand is there, but the land acquisition expense and public outrage of demolition makes upgrading the road impossible.
Hat's off, Colorado. Best planning I've seen since California. (That's a compliment
)