[COM] M2 Northern Connector | 15.5km | $867m

[neoballmon]

Although it does seem stupid not putting access in here, based on this render http://www.infrastructure.sa.gov.au/__d ... y_2011.JPG, it does look like it wouldn't be easy. They would need to overpass the overpass to get to the Northern Expressway, or they would need to also go under the overpass area.
The rail is too close for a loop after the bridge, and this would still require double-grade separations. Whilst possible, it would not be cheap...

I've made a quick sketch of how the double overpass could work.
http://img213.imageshack.us/img213/8130/nconnnorth.jpg

And here's a slightly more realistic looking example of a double overpass elsewhere in the world.

[drsmith]

Although it does seem stupid not putting access in here, based on this render http://www.infrastructure.sa.gov.au/__d ... y_2011.JPG, it does look like it wouldn't be easy. They would need to overpass the overpass to get to the Northern Expressway, or they would need to also go under the overpass area.
The rail is too close for a loop after the bridge, and this would still require double-grade separations. Whilst possible, it would not be cheap...

I've made a quick sketch of how the double overpass could work.
http://img213.imageshack.us/img213/8130/nconnnorth.jpg

And here's a slightly more realistic looking example of a double overpass elsewhere in the world.

An earlier plan had a direct northbound Port Wakefield Road/Northern Expressway connection which IIRC, involved two extra bridges, but not stacked on top of one another as you have shown. Ramps stacked one on top of the other is minimised as much as possible to reduce visual impact and the sheer amount of raw materials required for longer and higher ramps. The old USA way of doing it is not considered cool here.

The scale of the northern interchange, along with other changes are to reduce the $2bn cost estimated at that time. Othe changes included reducing the number of lanes on the Connector from 8 to 6, delaying the full construction of two previously planned interchanges and repositioning the rail from the centre median to the western side. The current northbound connection between the Port Wakefield Road and the Northern Expressway was built with the original rail-in-the-middle design.

[drsmith]

Although it does seem stupid not putting access in here, based on this render http://www.infrastructure.sa.gov.au/__d ... y_2011.JPG, it does look like it wouldn't be easy. They would need to overpass the overpass to get to the Northern Expressway, or they would need to also go under the overpass area.
The rail is too close for a loop after the bridge, and this would still require double-grade separations. Whilst possible, it would not be cheap...

I've made a quick sketch of how the double overpass could work.
http://img213.imageshack.us/img213/8130/nconnnorth.jpg

And here's a slightly more realistic looking example of a double overpass elsewhere in the world.

An earlier plan had a direct northbound Port Wakefield Road/Northern Expressway connection which IIRC, involved two extra bridges, but not stacked on top of one another as you have shown. Ramps stacked one on top of the other is minimised as much as possible to reduce visual impact and the sheer amount of raw materials required for longer and higher ramps. The old USA way of doing it is not considered cool here.

The scale of the northern interchange, along with other changes are to reduce the $2bn cost estimated at that time. Othe changes included reducing the number of lanes on the Connector from 8 to 6, delaying the full construction of two previously planned interchanges and repositioning the rail from the centre median to the western side. The current northbound connection between the Port Wakefield Road and the Northern Expressway was built for the original rail-in-the-middle design.

[Amused]

Yeah that's fair enough. I could better understand a more feasible connection with the rail line central along the corridor. Having said that it wouldn't be impossible to move the line slightly further away to make way for the connection.
Whilst I was initially concerned that a double merge would be problematic, I don't think the volume of southbound traffic attemptin to head east on the Northern Expressway would be that great and hence wouldn't be too concerning.
Either way, we'll just have to accept that we will see another half arsed go at road infrastructure to save money. Considering the light and medium industrial along the southern aspects of Port Wakefield, I'll be very interested if there is not some attempt to streamline road freight onto the northern expressway somehow. Right now the expectation is that semi trailers will happilly take a left turn from Pt Wakefield, travel over the connector and then a sharp right at the Waterloo Corner exchange.
This doesn't fill me with a lot of confidence but having said that, I'm just content that anything is being done to upgrade our road infrastructure at the moment.

[claybro]

This doesn't fill me with a lot of confidence but having said that, I'm just content that anything is being done to upgrade our road infrastructure at the moment.

Amused, I am also happy to see at something at least planned here and in general it looks like a pretty good outcome , but I am still at a loss to understand why the Northern connector is considered to need 6 lanes and the superway?, when planning for South Road is for limited upgrades, 4 lanes and low speed limits. I am also not filled with confidence that the end result of the "non stop south road" will be an adequate result even when it is finished, particularly given the high volume high speed roads tacked onto either end, but my thoughts on this are at length on other threads.

[claybro]

And here's a slightly more realistic looking example of a double overpass elsewhere in the world.

PS loved the thunderbirds style flyover example.

[muzzamo]

This doesn't fill me with a lot of confidence but having said that, I'm just content that anything is being done to upgrade our road infrastructure at the moment.

Amused, I am also happy to see at something at least planned here and in general it looks like a pretty good outcome , but I am still at a loss to understand why the Northern connector is considered to need 6 lanes and the superway?, when planning for South Road is for limited upgrades, 4 lanes and low speed limits. I am also not filled with confidence that the end result of the "non stop south road" will be an adequate result even when it is finished, particularly given the high volume high speed roads tacked onto either end, but my thoughts on this are at length on other threads.

Arent you forgetting about the lanes at street level? They are not going to vanish when the superway is built.

[claybro]

Dont the lanes under the Superway merge with the lanes on the Superway before it reaches Regency Road. ? Correct me if i'm wrong, but we wil have a 4 lane Northen Expressway 100km/h, interchanging with a 6 lane Northern connector 90-100km/h? onto the Superway 6 lanes 90km/h reducing to 4 lanes on top and service road underneath, total 8 lanes,(all good so far)..then merging to 4 lanes at Regency and reducing to 60-70km/h and 4 lanes for the most conjested stretch. I know we are broke, but I am just concerned the money spent on trenching and grade separation on South Road will be money wasted unless it is of sufficient capacity, of which I am not confident.

[Norman]

We don't even have a final
Design for the Superway to Anzac Highway section, so how can we say that it will be 2+2? Also I am sure the Superway is 3+3.

[AtD]

It's common for fast and wide rural freeways to turn into in narrow congested metro roads. Look at basically every major highway entering Sydney.

[claybro]

This is what worries me AtD. Sydney is a disaster-the worst major city in Australia road wise (except for Adelaide) and something we should not aspire to.. Perth and Melbourne on the other hand,is possible to drive right through the metro area and out the other side, appart from some bottle necks in peak hour and due to roadworks etc.

[Aidan]

We don't even have a final
Design for the Superway to Anzac Highway section, so how can we say that it will be 2+2?

Considering how much more expensive widening it would be, I think it's a safe assumption.

Also I am sure the Superway is 3+3.

N of Grand Junction Road it's 3+3.
S of Grand Junction Road it's 2+2 (+ another 2+2 lanes at ground level).

[Aidan]

It's common for fast and wide rural freeways to turn into in narrow congested metro roads. Look at basically every major highway entering Sydney.

From Newcastle that's true, though a tunnel is likely to be constructed to solve the problem. Likewise from the Illawarra where this week's announcement that the Southern Freeway would be extended into Sydney was met witth skepticism by those who had heard it all before. But the Hume Highway (The main route in from Adelaide, Canberra and Melburne) links onto other motorways, while from the Blue Mountains the situation is almost the exact opposite, with a narrow rural road turning into a freeway.

[ChillyPhilly]

Reckon South Road will go 3+3 between Torrens and Port Roads?

[claybro]

Reckon South Road will go 3+3 between Torrens and Port Roads?

Hope so, there will be plenty of room when the buildings on the Western side are all removed (I believe these have already been aquired). Be interesting to see how they handle the Hawker street intersection. I also wonder how they will handle the Regency to Torrens Road section, specially the sharp bend near the Torrens Road end of that stretch. The RAA flythrough from a couple of years back looks a bit un-realistic in this section unless one side of this is also aquired and cleared. Perhaps this sharp bend can be straightened out altogether by removing houses on the Western side of this bend and align it with the intersection. (suppose we have moved off the Northern Connector topic)