[U/C] M2 North-South Motorway

[Spotto]

- And to retain the TBMs upon project completion for other uses, especially a cross-CBD (or city) rail tunnel.

As I believe has been mentioned previously, the motorway TBMs will be way too massive for a CBD rail tunnel. A TBM digging a three lane motorway (West Gate Tunnel TBMs are 15.6m in diameter) is ridiculously oversized for a tunnel that will carry a single length of track (Metro Tunnel TBMs are only in 7.1m diameter). And no, they wouldn't use a single TBM and put both sets of tracks in a single tunnel.

[aceman]

[quote=ChillyPhilly post_id=199554
- Encouraging the design to cater for freight movement and not commuter traffic;
[/quote]

bit late for that. 90% of the traffic on the southern expressway end are normal cars commuting and I would say that thousands of commuters also use the northern end. freight movement isn't just restricted to the middle section. if there's a motorway running through the middle of a major city it's going to be used by everyone freight or not. they're not going to spend billions on tunnels and only cater it for trucks. I lived in Sydney for 3 years and all the motorways there were predominantly used by regular commuters.

[SBD]

- Encouraging the design to cater for freight movement and not commuter traffic;

bit late for that. 90% of the traffic on the southern expressway end are normal cars commuting and I would say that thousands of commuters also use the northern end. freight movement isn't just restricted to the middle section. if there's a motorway running through the middle of a major city it's going to be used by everyone freight or not. they're not going to spend billions on tunnels and only cater it for trucks. I lived in Sydney for 3 years and all the motorways there were predominantly used by regular commuters.

I don't think anyone is saying that the motorway will not be used by commuters. The point is that it is to help people who are making longer trips, and facilitate getting the through traffic (especially trucks) off of the suburban roads that might have pedestrians and kids on bikes.

The reality is that the cohort of people who want to commute by car for over an hour each way will discover that better roads mean they have to live further from work to maintain that lifestyle, so over time, "induced demand" will fill any new road. The design stage is when the powers-that-be can also make sure it meets the freight need as well, so the trucks are already there when commuters decide where to buy their next house or find their next job.

[aceman]

at the end of the day regardless of who uses this motorway if the design, entry/exit points are not done correctly we'll end up with a grid locked motorway through the central west. hopefully it won't end up a laughingstock like the previous one way southern expressway.

[Saltwater]

My sense is the tunnels are largely catering for people or freight travelling longer distances. Someone in the southern section that wants to go to Castle Plaza will still use the surface road, likewise people living along the northern section travelling to Brickworks will still use the surface road. This reduces traffic passing through entrances & exits onto the motorway, so reduces the risk of accidents and delays along the entire corridor. Its inevitable people will also use the tunnels to commute, and if the volume reaches a point they regularly experience delays, they will start seeking alternatives like public transport or travelling earlier / later in the day. Or just grin and bear it.

I don't think it will be a laughing stock because its at least two-way rather than the initial Southern Expressway, and based on the current documents, three lanes in each direction. Which given much of South Road is only two lanes in each direction today, is a great result.

[Nort]

My sense is the tunnels are largely catering for people or freight travelling longer distances. Someone in the southern section that wants to go to Castle Plaza will still use the surface road, likewise people living along the northern section travelling to Brickworks will still use the surface road. This reduces traffic passing through entrances & exits onto the motorway, so reduces the risk of accidents and delays along the entire corridor. Its inevitable people will also use the tunnels to commute, and if the volume reaches a point they regularly experience delays, they will start seeking alternatives like public transport or travelling earlier / later in the day. Or just grin and bear it.

I don't think it will be a laughing stock because its at least two-way rather than the initial Southern Expressway, and based on the current documents, three lanes in each direction. Which given much of South Road is only two lanes in each direction today, is a great result.

Also for most sections the surface level roads still provide 1-2 lanes of traffic in each direction.

[Spotto]

My sense is the tunnels are largely catering for people or freight travelling longer distances. Someone in the southern section that wants to go to Castle Plaza will still use the surface road, likewise people living along the northern section travelling to Brickworks will still use the surface road. This reduces traffic passing through entrances & exits onto the motorway, so reduces the risk of accidents and delays along the entire corridor. Its inevitable people will also use the tunnels to commute, and if the volume reaches a point they regularly experience delays, they will start seeking alternatives like public transport or travelling earlier / later in the day. Or just grin and bear it.

Exactly, this is the whole point. The entrances and exits still need to be arranged better but the motorway is there primarily for traffic travelling longer distances through Adelaide or passing through completely. The motorway might allow them to get to places in Adelaide faster but it won't drop them at the doorstep of their final destination because that's not what motorways do, ultimately the end of their journeys will involve the surface roads.

[aceman]

I think we need to keep in mind that the remaining section of this motorway goes through the most densely populated part of it's entire length. if they don't get the entry/exit points right we'll end up with major congestion and bottlenecks. we can debate about whether it should be for freight or commuting until the cows come home but the reality is that if there's a motorway there people will use it regardless of what their intentions are. this has been the case in Sydney and Melbourne for decades. here in SA we also don't need to worry about paying a toll either. no toll means it will get used by everyone.

[mattwinter]

It's definitely a balancing act. You could overdo the entry exit points and have the motorway filled with people doing 10 minute trips. But not enough entry-exit points will mean they clog up.

I think at the moment the plan just needs a bit more balance. Three off ramps heading south maybe feels like one too many. Four on ramps heading north probably feels like one too many as well. Only one off ramp heading north doesn't feel like enough.

Just putting a northbound off ramp at Richmond Road would mean that at least City traffic is not using the same exit as airport and richmond road traffic. Ideally doing something at Emerson would be best I think.

[bits]

I am sure on/off ramps will be placed to avoid unnecessary shorts trips wanting to use the motorway.
Eg the local shops of Castle Plaza should not be a destination of the motorway.

South Road will remain for locals to use for the their daily commute to the city and their weekly supermarket visits.
The Motorway will have entry/exits that try to avoid locals using it to skip 4 sets of lights to their local destinations.

[aceman]

so you're saying that someone travelling south and entering the motorway at tonsley shouldn't exit at Darlington where macdonalds is because they are trying to avoid 5 sets of traffic lights?? so there should be a minimum distance traveled on it otherwise it shouldn't be used?? I had no idea that this motorway had conditions of use that are distance based. wow we really are special here in SA. this discussion wouldn't happen anywhere else in the country only adelaide. I'll refer to Sydney as an example because I lived there previously but over there people pay a monthly toll subscription just so they can skip out 5 sets of bottlenecked traffic lights. they don't get on the motorway and travel 100kms.

[SBD]

so you're saying that someone travelling south and entering the motorway at tonsley shouldn't exit at Darlington where macdonalds is because they are trying to avoid 5 sets of traffic lights?? so there should be a minimum distance traveled on it otherwise it shouldn't be used?? I had no idea that this motorway had conditions of use that are distance based. wow we really are special here in SA. this discussion wouldn't happen anywhere else in the country only adelaide. I'll refer to Sydney as an example because I lived there previously but over there people pay a monthly toll subscription just so they can skip out 5 sets of bottlenecked traffic lights. they don't get on the motorway and travel 100kms.

There are a number of roads that cross the Southern Expressway and South Eastern Freeway without interchanges. Northern Expressway and Connector cut a number of roads, but have interchanges at all the ones that still cross it. Interchanges are mostly between intersecting roads rather than at them between the River Torrens and Port River Expressway.

For your Sydney comparison which crossovers would you add interchanges at to facilitate local traffic using the freeway/motorways? Does (and should) the SEF carry local traffic between the new Bald Hills interchange and Mount Barker Interchange? Is the reason it needs widening between Crafers and Stirling because a lot of traffic is using it just between those two interchanges? Would an alternative be to have added a new local road by upgrading Ayers Hill and Waverley Ridge Roads?

Presumably you would add an interchange at Majors Road. What about Yong Street, O'Sullivan Beach Road, Flaxmill Road, Honeypot Road? On the SEF there are Old Carey Gully Road and Old Mount Barker Road between Stirling and Bridgewater; River Road and Echunga Road between Verdun and Mount Barker; Summit Road and Back Callington Road between Bald Hills and Callington. These are the ones with bridges. There may be others that were cut. They are all local roads that at the time the freeway was built, a decision was made that people who wanted to access it could continue on local roads to access major interchanges elsewhere. Bald Hills and Monarto interchanges have been added to support changing traffic needs.

I'd say the remaining part of the NS Motorway needs to provide interchanges to gain access to and from the SEF (either at Emerson or elsewhere) from both north and south, the airport from both ways and city from the south. I don't see it as important to be able to provide an 80kmh non-stop road to get from Tonsley or Flinders to Castle Plaza. If that happens, fine, but it need not be a design goal. Maybe the city needs two exits like Mount Barker, Gawler and Nuriootpa have.

[Spotto]

Maybe the city needs two exits like Mount Barker, Gawler and Nuriootpa have.

I agree with the entire rest of your post, but just on this point. The city will already have two exits once T2D is complete: Port Road for traffic from the north and Anzac Highway for traffic from the south, and the Airport exit will probably be able to function as a third city exit too.

[mawsonguy]

One issue that I don't believe has been adequately addressed is, how quick you clear the traffic from the exit ramp. Under the proposed design, traffic travelling from the north to the city will exit the tunnel north of Henley Beach Road. That traffic has to merge with the traffic travelling south on the surface road. It then has a short section of surface road before the city bound traffic can turn left onto Henley Beach Road. This section is currently the site of significant congestion. My observation is that a large part of the traffic using the sections currently local traffic.

There is only one very shortly left turn filter lane and you have to stop if traffic is travelling east on Henley Beach Road.Traffic can continue on to Sir Donald Bradman Drive, where the filter lanes before and after the left turn have a reasonable length, but that only continues the congestion. I think some serious consideration needs to be given to managing traffic exiting the tunnel and turning left onto Henley Beach Road.

[TorrensSA]

Majors Road should have an interchange. It will help traffic from Brighton Road heading south and Hallett Cove heading north, it will take traffic off of Brighton and Sturt Roads.