By splitting Fullarton Road into two one-way access roads from the Britannia intersection, with northbound traffic heading along Dequiteville/Hackney/Mann roads, and southbound traffic heading along Fullarton, Bailol, Pembroke, Eton, Bruton and Park roads, it transforms the intersection into a standard 4-way traffic junction. Each one-way corridor would be serviced by the same amount of traffic lights along its course, so that neither traffic flow is favored by a quicker access time. (I do propose the closure of Bartels Rd and also re-aligning Rundle Road so that it goes into Grenfell St, creating a east-west traffic corridor across the CBD from Glover Avenue into the Parade)
The southbound lane would require minimal property acquisition from St Peter's College along Bailol, Pembroke and Eton streets to suffice a 4-lane traffic corridor and the diversion from Park Tce into Bruton St would use the land now vacated by the former Channel Seven studios. In the event this couldn't happen, a costlier (but more direct option) would be to cut straight across from Bruton St into Park Tce, compulsorily acquiring the units that are in the way. (see the dark grey route on map)
During the course of the Clipsal 500, northbound traffic would simply be re-directed along to share with the southbound route, reducing both lanes to two in each direction.
Oh and if it makes the Parklands Society happy, they'll get some parklands space because Dequiteville Terrace would be a 4-lane road, not the 6-8lane monstrosity that it is, alongside the closure of Bartels Rd. Fullarton Road (north of the Britannia intersection) is already a 2x2 road, which would just be converted to a 4 lane one way road, with no on-street parking.
