I dont know if this has been posted or discussed here before, but one of the proposals out there involves removing the I-345 spur that links I-45 with US75. The traffic going from I-45 to 75 would simply reroute around the CBD on the mix-master.
The spur has reached its end-of-life and the cost to rip it out would be roughly equal to what it would cost to do a full replacement of the expressway.
If we could rip the spur out, the land that would be freed up would be revitalized and returned to urban, walkable, livable space:
http://www.ANewDallas.com/
Scroll down on the page to check out the Vision of how the land would be utilized! Pretty impressive.