[U/C] M2 North-South Motorway

[Spotto]

Surely the $200M odd for the design will include some proper traffic modelling.

Depending on the location of the tunnel entrances, you may find 2 lanes is entirely appropriate. For example, they could aim this for primarily N-S freight movements and restrict city-bound movements. However, I doubt this will happen. After all, the aim of this project is to give Boothby residents an unobstructed 1 person per vehicle drive to their city jobs, right? </sarcasm>

In terms of tunnel entrances, I'd personally keep it simple. Northern portal at Torrensville joining with the T2T, Southern portal at Tonsley joining the Darlington Project, and a central portal at Emerson Crossing (futureproofing in case Cross Road Motorway happens).

Keep the tunnels primarily for longer-distance traffic and people who want to avoid the city altogether, local and citybound traffic can use the surface road. If you have too many entrances for the tunnels, everyone will just use the tunnels (especially with its proximity to the city) and the problem won't be fixed. Traffic needs to be shared evenly between the tunnels and the surface road.

[croweater888]

That is unlikely to happen. I'd wager on:
A pair of 3 lane tunnels, either side by side, or on top of one another, that have entry and exit points near ANZAC Highway/Gallipoli Underpass.
Why? The volume of traffic recorded for the area between the Gallipoli Underpass and Emerson Crossing is >50000, but 20001 - 50000 at both the underpass and the crossing.
There is also a recording of >50000 between Ackland St and Raglan Avenue, a notorious bottleneck after the crossing.

Emerson Crossing should be a lowered level, like Port Road Crossing.

[SBD]

It'd be nice if someone has done a preliminary plan for "what next" to connect the South Eastern freeway to the North-South Motorway and provide a freeway-style junction in the right place as part of the NSM. At the moment, we don't really know if that will be the Cross Road alignment, or something like Glen Osmond and Greenhill Roads, or Portrush/Hampstead/Grand Junction or a completely new alignment with tunnels.

If Cross Road is the chosen alignment, then Emerson will eventually need at least four levels including the railway, and quite a lot of space for on and off ramps in all/most directions as neither freeway should have traffic queued for stop lights.

[rev]

Cross road should be the option taken, followed by Portrush/Lower Portrush and some alignment further north towards Dry Creek and link it with PREXY/NC/SW interchange, with the intent to create a proper ring route.

[Westside]

I doubt any Government would be looking to install a MATS-like interchange (originally designed for Thebarton) at Emerson. Those types of interchanges just aren’t seen or are necessary in urban environments. We probably won’t ever get a freeway-grade Cross Rd either. You can do a lot for traffic volumes with a few underpasses and a high capacity tunnel portal exiting at an at-grade Cross Rds. The main importance should be in removing the level crossing from the mix, not creating a multi-level traffic light-free vehicle interchange.

[Spotto]

I doubt any Government would be looking to install a MATS-like interchange (originally designed for Thebarton) at Emerson. Those types of interchanges just aren’t seen or are necessary in urban environments. We probably won’t ever get a freeway-grade Cross Rd either. You can do a lot for traffic volumes with a few underpasses and a high capacity tunnel portal exiting at an at-grade Cross Rds. The main importance should be in removing the level crossing from the mix, not creating a multi-level traffic light-free vehicle interchange.

I'm not suggesting a complex light-free interchange, the only light-free elements would be the NSM tunnels and the rail line. I'm not sure what impact the tunnel solution and/or the rail grade separation would have on the current overpass whether it would be too heavy, but in this scenario let's work with what we already have and presume the overpass (Level 1) and current intersection (Ground Level) both stay, the railway is lowered to pass under the intersection (Level -1) and the northbound/southbound tunnels pass uninterrupted further beneath that (Level -2) giving us a four-level intersection.

The tunnel access portals can exist on South Road several hundred metres away from the current signalised intersection. A car travelling westbound on Cross Road wanting to use the northbound tunnel will turn right onto South Road as currently, then a few hundred metres north of the intersection, can access the tunnel portal and follow the tunnel through to the T2T and beyond.

[Eurostar]

Here is how the South Eastern Freeway should be connected with South Road.

Stage 1: Tunnel from Glen Osmond to Eastwood
Stage 2: Tunnel or Elevated Road from Eastwood to Keswick

Glen Osmond to Keswick Connection

[ChillyPhilly]

An elevated road along Greenhill Road will never happen.

[Llessur2002]

An elevated road would look awful along the edge of the parklands. They have no place in the suburbs imho.

[Spotto]

Greenhill Road is too far in, the motorways should be slightly further out. Essentially, an "outer ring route" for mostly suburban and long-distance use in contrast to the current City Ring Route for most inner suburbs and city bound traffic.

Also, connecting the CBD so directly to SEF would be a big mistake IMO. We know that if you build it they will come: all that would accomplish is risk encouraging a wave of new people driving directly into the CBD for work (to which we don't have enough parking) instead of finding other means.

[Eurostar]

Alternative i thought to tunnel/elevated road was having a truckway along the median corridor of Greenhill Road with truck light priority at the intersections.

[Eurostar]

It'd be nice if someone has done a preliminary plan for "what next" to connect the South Eastern freeway to the North-South Motorway and provide a freeway-style junction in the right place as part of the NSM. At the moment, we don't really know if that will be the Cross Road alignment, or something like Glen Osmond and Greenhill Roads, or Portrush/Hampstead/Grand Junction or a completely new alignment with tunnels.

If Cross Road is the chosen alignment, then Emerson will eventually need at least four levels including the railway, and quite a lot of space for on and off ramps in all/most directions as neither freeway should have traffic queued for stop lights.

Cross road tunnel or underpasses would be very expensive

[Simmos083]

Why not build a tunnel all the way down cross road? Makes more sense and easily accessible to the north south motorway. We must have a better freeway/motorway system in Adelaide which will require spending big to get us moving. Fat too many traffic lights in Adelaide which holds up traffic. The ANZAC highway/south road interchange could be done in a way where there is no traffic lights but on/off ramps which will. Benefit both ANZAC highway getting that moving and the north south motorway.

[rev]

Here is how the South Eastern Freeway should be connected with South Road.

Stage 1: Tunnel from Glen Osmond to Eastwood
Stage 2: Tunnel or Elevated Road from Eastwood to Keswick

IMG_20190619_094208.png

Greenhill Road is too far in, the motorways should be slightly further out. Essentially, an "outer ring route" for mostly suburban and long-distance use in contrast to the current City Ring Route for most inner suburbs and city bound traffic.

Also, connecting the CBD so directly to SEF would be a big mistake IMO. We know that if you build it they will come: all that would accomplish is risk encouraging a wave of new people driving directly into the CBD for work (to which we don't have enough parking) instead of finding other means.

We're going to need more then a ring route in the near future.

[Llessur2002]

I'm not sure I buy the argument that we're going to need more big roads in the future to cope with increased congestion. In fact I would say there is a strong argument that we're approaching peak congestion with the rapidly impending semi-automation and eventual full-automation of vehicles. Especially here in Adelaide with our low population growth and our lack of anything approaching significant traffic problems on a global or even a national scale.

Many of our arterial roads are already three lanes in each direction which is significantly bigger than those found in many much larger cities around the world, especially in Europe. Automation should enable traffic to flow much more freely with this existing capacity, even with the same number of intersections as we have now. We'll just be using them smarter.

I don't anticipate we'll see much in the way of major new/significantly upgraded inner metropolitan roads after the NS motorway is complete - except, potentially, for a link to the SE Freeway. We're realistically talking a couple of decades at an absolute minimum to get those finished by which point automation will be far more advanced than it is now as will other transportation modes such as air-based ride sharing.

I'd expect to see some fiddling around with troublesome intersections, better synchronisation of traffic signals, continued grade separation of public transport and that's about it.