Remember this post? Remember this picture?
Mormon apartment building, I thought I'd bring it back to life, and put more meat on them bones.
In the cloverleaf, we build a new "Sydenham Mall" (Sydenham being the name of the interstitial street between 15th and 16th); flanking it, large buildings fronting each of the four corners. They would share mechanicals and loading docks in the cloverleaf curve; inasmuch as possible, they would cover the interchange. Retail fronting Sydenham would lead up to the Provence*; retail fronting 16th would help urbanize that street further; flex space would front 15th.
Between all of these additions, the Vine Street Expressway would be completely hidden from 12th to 21st-ish. It would become the perfect example of the proper placement of heavy transportation infrastructure in the city--grade-separated, out of mind.**
*If the Provence is built. As you may recall, I noted in A Provincial "Provence" that turning the cloverleaf green is, in fact, the worst possible for it.
**Remember, in Death and Life, Jane Jacobs noted that the most marginal uses--and hence the worst land values--were (in her time) usually located next to railroad tracks; this can be expanded to include Interstates today, for various reasons. Both are heavy infrastructure. The fact of the matter is that heavy transportation infrastructure, while indubitably necessary for the city to function properly (to get imports in and exports out à la her economies trilogy), also have a depressing effect on adjacent land. My extension of this point is--one of planning's major goals should thus be minimization of this effect by making heavy transpo infra "invisible" from an urban-dynamics point of view.