[U/C] North-South Motorway

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aceman
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[U/C] Re: North-South Motorway

#3511 Post by aceman » Sat Mar 09, 2019 8:49 pm

doesn't gallipoli underpass need to be widened?

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[U/C] Re: North-South Motorway

#3512 Post by Vasco » Sat Mar 09, 2019 8:58 pm

aceman wrote:doesn't gallipoli underpass need to be widened?
Uninformed guess; reduce the width of the median strip and convert the bike/emergency lanes, provides for a 3rd land on each side?


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[U/C] [U/C] Re: [U/C] Re: North-South Motorway

#3513 Post by Mr Messy » Sat Mar 09, 2019 9:13 pm

Vasco wrote:
aceman wrote:doesn't gallipoli underpass need to be widened?
Uninformed guess; reduce the width of the median strip and convert the bike/emergency lanes, provides for a 3rd land on each side?


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The Gallipoli underpass is about 20m wide and the T2T motorway is about 25m wide
Edit: Gallipoli is 22m

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[U/C] Re: North-South Motorway

#3514 Post by Vasco » Sat Mar 09, 2019 9:20 pm

Mr Messy wrote:
Vasco wrote:
aceman wrote:doesn't gallipoli underpass need to be widened?
Uninformed guess; reduce the width of the median strip and convert the bike/emergency lanes, provides for a 3rd land on each side?


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The Gallipoli underpass is about 20m wide and the T2T motorway is about 25m wide
Has it been stated anywhere that the whole motorway is going to be one consistent width? Tunnel proposal renders show only 2 lanes in one direction. Southern expressway chops and changes between differing numbers of lanes etc.


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[U/C] Re: North-South Motorway

#3515 Post by SBD » Sun Mar 10, 2019 12:33 am

Vasco wrote:
Sat Mar 09, 2019 9:20 pm
Mr Messy wrote:
Vasco wrote:
Uninformed guess; reduce the width of the median strip and convert the bike/emergency lanes, provides for a 3rd land on each side?


Sent from my iPhone using Tapatalk
The Gallipoli underpass is about 20m wide and the T2T motorway is about 25m wide
Has it been stated anywhere that the whole motorway is going to be one consistent width? Tunnel proposal renders show only 2 lanes in one direction. Southern expressway chops and changes between differing numbers of lanes etc.
I thought it had been described as three lanes all the way. That is clearly a bit of a loose description as northbound on the Superway narrows to two lanes above Grand Junction Road, then returns to three lanes by adding the on-ramp. Something similar could easily be done at Anzac Highway which will clearly become a major exit for northbound commuter traffic, with "left lane must exit" before the underpass rather than just a squeeze.

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[U/C] Re: North-South Motorway

#3516 Post by Nort » Sun Mar 10, 2019 12:19 pm

The Anzac Highway/South Road intersection is pretty much the primary point for traffic entering/leaving South Road. On those grounds they may think that 2 lanes each way through the underpass is enough. Going down to 2 lanes at that point also allows merging traffic to enter and turn the road back into 3 lanes in a safer manner.

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[U/C] Re: North-South Motorway

#3517 Post by claybro » Sun Mar 10, 2019 12:20 pm

It should be a consistent width for the entire length. Merging lanes is one of the biggest causes of freeway congestion- (besides over capacity). That setup at the top of the superway is not ideal.

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[U/C] Re: North-South Motorway

#3518 Post by how good is he » Sun Mar 10, 2019 2:07 pm

I agree. It was poor that the T2T near the cemetery/River Torrens goes from 3 lanes to 2 and back to 3. With the Pym St exit/entrance they should hurry up and use the vacant land they own as well as demolish as much as allowable to widen the road (even if it’s only one side) well before they build the overpass to maximise traffic flow to Regency Rd as it can be a bad bottleneck now going from 3 to 2 lanes.

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[U/C] Re: North-South Motorway

#3519 Post by SBD » Sun Mar 10, 2019 5:48 pm

claybro wrote:
Sun Mar 10, 2019 12:20 pm
It should be a consistent width for the entire length. Merging lanes is one of the biggest causes of freeway congestion- (besides over capacity). That setup at the top of the superway is not ideal.
I'm only an irregular user, but I've never noticed an issue with the narrowing before the Grand Junction on-ramp. Issues at the moment come from the further tightening to get to Salisbury Highway, so it could well become an issue later once the Northern Connector is open. Alternatively, perhaps it is better to merge three flowing lanes to two than it is to merge the on-ramp into three continuing lanes. Does anyone know where to find international/national standards for building freeway interchanges? It's likely that someone, somewhere has done research and recommendations for how to manage traffic near on and off ramps to minimise collisions, near-misses and congestion (and I'm happy for safety to rank above convenience if they conflict).

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[U/C] Re: North-South Motorway

#3520 Post by claybro » Sun Mar 10, 2019 5:53 pm

Also I am obviously an infrequent user, however I would suggest the reason the narrowing of the superway to 2 lanes at GJR is not causing issues at present is because it is rarely very busy now. Things will change dramatically when it connects on to the Northern connector, and I reckon this pinch point will become a real issue with trucks slowing and trying to merge at this spot.

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[U/C] Re: North-South Motorway

#3521 Post by Goodsy » Sun Mar 10, 2019 6:14 pm

claybro wrote:
Sun Mar 10, 2019 5:53 pm
Also I am obviously an infrequent user, however I would suggest the reason the narrowing of the superway to 2 lanes at GJR is not causing issues at present is because it is rarely very busy now. Things will change dramatically when it connects on to the Northern connector, and I reckon this pinch point will become a real issue with trucks slowing and trying to merge at this spot.
I think they'd be anticipating most of the southbound truck traffic to exit the North South Motorway at the PRexy or Grand Junction road

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[U/C] Re: North-South Motorway

#3522 Post by ChillyPhilly » Sun Mar 10, 2019 6:15 pm

Elevated structure (North of Edward Street to South of Daws Road)
- This area is predominantly industrial/commercial and includes known contaminated soils that would
require expensive remediation/disposal if disturbed;
- Lots of side road connections including East-West movements that service local area and facilities
that do not need to interact onto the N-S Corridor;
26
- Minimal loss to visual amenity due to duplicating the existing elevated roadway over the rail corridor
at Cross Road;
- Shallow groundwater along this road section leading to ongoing maintenance effort if an alternative
treatment was selected;
- Greater flexibility for future rail/road separation as part of Emerson crossing upgrade.
Our state, our city, our future.

All views expressed on this forum are my own.

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[U/C] Re: North-South Motorway

#3523 Post by claybro » Sun Mar 10, 2019 6:59 pm

Goodsy wrote:
Sun Mar 10, 2019 6:14 pm
claybro wrote:
Sun Mar 10, 2019 5:53 pm
Also I am obviously an infrequent user, however I would suggest the reason the narrowing of the superway to 2 lanes at GJR is not causing issues at present is because it is rarely very busy now. Things will change dramatically when it connects on to the Northern connector, and I reckon this pinch point will become a real issue with trucks slowing and trying to merge at this spot.
I think they'd be anticipating most of the southbound truck traffic to exit the North South Motorway at the PRexy or Grand Junction road
It's travelling north that will be the problem. 2 lanes will most definitely cause a bottleneck when the rest of it is 3 Lanes leading up to that point. I would hate to see them repeat this potential problem at Emerson.

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[U/C] Re: North-South Motorway

#3524 Post by Bacon » Sun Mar 10, 2019 7:07 pm

claybro wrote:
Sun Mar 10, 2019 6:59 pm
Goodsy wrote:
Sun Mar 10, 2019 6:14 pm
claybro wrote:
Sun Mar 10, 2019 5:53 pm
Also I am obviously an infrequent user, however I would suggest the reason the narrowing of the superway to 2 lanes at GJR is not causing issues at present is because it is rarely very busy now. Things will change dramatically when it connects on to the Northern connector, and I reckon this pinch point will become a real issue with trucks slowing and trying to merge at this spot.

I think they'd be anticipating most of the southbound truck traffic to exit the North South Motorway at the PRexy or Grand Junction road
It's travelling north that will be the problem. 2 lanes will most definitely cause a bottleneck when the rest of it is 3 Lanes leading up to that point. I would hate to see them repeat this potential problem at Emerson.
The actual road is wide enough to accommodate 3 lanes, it’s just that it’s painted as 2 lanes at the moment.

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[U/C] Re: North-South Motorway

#3525 Post by SBD » Sun Mar 10, 2019 7:23 pm

Bacon wrote:
Sun Mar 10, 2019 7:07 pm
claybro wrote:
Sun Mar 10, 2019 6:59 pm
Goodsy wrote:
Sun Mar 10, 2019 6:14 pm



I think they'd be anticipating most of the southbound truck traffic to exit the North South Motorway at the PRexy or Grand Junction road
It's travelling north that will be the problem. 2 lanes will most definitely cause a bottleneck when the rest of it is 3 Lanes leading up to that point. I would hate to see them repeat this potential problem at Emerson.
The actual road is wide enough to accommodate 3 lanes, it’s just that it’s painted as 2 lanes at the moment.
Someone said the Gallipoli Underpass is 3 metres narrower than the T2T trench, hence the assumption that one direction will need to be only two lanes.

If Bill Shorten's plan that the road is predominantly for commuters from the Southern Suburbs comes to pass, then I imagine that "left lane must exit" northbound at Anzac Highway will actually help traffic to flow quite well. It's hard to imagine that less than a third of the traffic would be CBD commuters.

If the plan remains that it is predominantly a freight route, it is still likely to have a substantial amount of traffic turn off in that area, as there is unlikely to be another exit before Richmond Road if I've read the plans properly.

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