After the North South Corridor..

[Westside]

Bring back the 340, make it express and increase frequency. That should get some traffic off TH Rd!

[[Shuz]]

- East-West link, likely underneath A3 Cross Road or nearby route connecting the North South Motorway to the South Eastern Freeway, as three lane dual carriageway twin tunnels. Rebadged as an extension of the South Eastern Freeway. (M8 designation).

- Upgrade of M1 South Eastern Freeway to three lane dual carriageway between Crafers and Mount Barker. Reclassified designation to match Western Highway / Freeway in Victoria. (M8 designation).

- Upgrade of the A8 Dukes Highway between Murray Bridge and Victorian border to two lane dual carriageway freeway standard. Rebadged as either an extension of the South Eastern Freeway or Dukes Freeway. Delivered in multiple stages. (M8 designation).

- Upgrade of A9 Port River Expressway and Salisbury Highway to Elder Smith Road to three lane dual carriageway freeway standard. Rebadged as Port River Expressway for whole length, route is currently classified as A9. (M9 designation).

- Upgrade of A13 Victor Harbor Road to two lane dual carriageway freeway standard. Rebadged as an extension of the Southern Expressway. Delivered in two stages; Stage 1 to Mount Compass, Stage 2 to Victor Harbour. (M2 designation).

- Upgrade of A1 Princes Highway to two lane dual carriageway freeway standard. Rebadged as Princes Freeway. Delivered in three stages, Stage 1: Northern Expressway to Two Wells, Stage 2: Two Wells to Dublin, Stage 3: Dublin to Port Wakefield. (M1 designation).

- Upgrade of A20 Main North Road (Elizabeth), Gawler Bypass and Sturt Highways to three lane dual carriageway freeway standard from Elizabeth to Barossa, and two lanes dual carriageway thereafter. Delivered in multiple stages to New South Wales border. Rebadged as Sturt Freeway. (M20 designation).

- Upgrade of A18 McIntyre Road from Modbury, construction of new bypass past Golden Grove and link to Main North Road at Salisbury Heights. Three lane dual carriageway freeway standard. Rebadged as extension of Sturt Freeway. (M20 designation).

[SBD]

I think the Truro Bypass has already been announced. That should be joined with the current end of the two-lane dual carriageway. I agree with Shuz it should eventually also be extended all the way to the state border in stages. It will need a new route from Waikerie to pass south of Loxton (roughly along the boundary between irrigated and crop land) instead of through Barmera, Monash and Renmark.

The connection from the road from Melbourne to the North-South Motorway will need to be the next big project when the NSM is approaching completion. I think the experience with the gradient between Measdays Hill and Glen Osmond will work against continuing that grade round a corner into a tunnel.I wonder what the public response to a "short south" freeway from Mount Barker Springs to Darlington would be. That would get many trucks off of the long descent, and reduce the pressure on Mt Barker to Stirling.

Duplicating the Swanport Bridge is also a key stand-alone project linking the South Eastern Freeway to over 20km of dual carriageway to past Tailem Bend.

Expanding to dual carriageway and grade-separating major intersections on the interstate highways should be a long-term goal, but I'm not sure that full freeway standard is necessary, perhaps left-in/left-out with sheltered U-turn bays for smaller local connections where no practical alternatives are available.