[U/C] M2 North-South Motorway

[Raider]

The update doesn't seem to mention the Tonsley rail extension.

[Norman]

Saw the massive new Bunnings being built near Castle Plaza on South Rd set back only some 1-2m away from the boundary & road. I don’t know what the DTPI plan is - but heaven help if they have to acquire properties on either side for road widening. Based on what I saw it almost has to be a tunnel.

The room required for the motorway was factored into the planning approval from what I heard. Apparently the motorway will be on the east side at this section.

[Norman]

The update doesn't seem to mention the Tonsley rail extension.

While both projects are at the same location, the projects are seperate and being built by different consortiums as far as I know

[SBD]

The update doesn't seem to mention the Tonsley rail extension.

While both projects are at the same location, the projects are seperate and being built by different consortiums as far as I know

The railway project's completion date is later than the Darlington project's. I would imagine that the plan includes the railway bridge deck being in place before the road opens to traffic though. There appear to be piers on each side of the trench between it and the surface roads so it may be that the timing is intended to be when cranes can be positioned in places that still permit through traffic.

[ChillyPhilly]

Saw the massive new Bunnings being built near Castle Plaza on South Rd set back only some 1-2m away from the boundary & road. I don’t know what the DTPI plan is - but heaven help if they have to acquire properties on either side for road widening. Based on what I saw it almost has to be a tunnel.

Bunnings' development application hinted that following discussions with DPTI, property on the east of that stretch of South Road is to be acquired.

[how good is he]

Yes I understand but on that opposite east side you have things like McDonalds/KFC, a massive OTR and 200+ big businesses as well. So are you saying they are likely to go?

[Aidan]

Well Aidan, stopping short of 1985 flying DeLoreans, what do you propose?

Can't you tell from what I'd written?
I propose Pym Street be extended over or under South Road. I think a steel bridge over South Road would be the best value way to do it, as that would be thinner than a concrete bridge and therefore enable the approach ramps (which would be as steep as the buses can reliably manage) to be shorter.

[Aidan]

Yes I understand but on that opposite east side you have things like McDonalds/KFC, a massive OTR and 200+ big businesses as well. So are you saying they are likely to go?

The massive OTR is in St.Marys. I expect it's planned to return to the west side before then, to avoid the heritage listed cemetery and the substation by the Daws Road intersection.

Edit: ...and the Chemist Warehouse redevelopment plans (moving CW, closing Rite Price Grocery Clearance, building Aldi) include provision for widening South Road on the west side.

[SBD]

Well Aidan, stopping short of 1985 flying DeLoreans, what do you propose?

Can't you tell from what I'd written?
I propose Pym Street be extended over or under South Road. I think a steel bridge over South Road would be the best value way to do it, as that would be thinner than a concrete bridge and therefore enable the approach ramps (which would be as steep as the buses can reliably manage) to be shorter.

If the North-South Motorway nor South Road can be lowered in that area due to subsurface services, then a ramp at wheelchair accessible slope (1 in 12) would need 60m approach ramps to get 5m above the roads. Since the clearance under the bridge needs to be 5m and the bridge itself could be over 2m from the lowest point under it to the road deck, the approach would need to be over 84m long on each side. The width required in Pym Street would be at least a footpath, bike lane and car lane each side of the bridge for access to/from South Road, and the same in each direction over the bridge. I think that is 6.6m each way at each level, plus centre lines, kerbs and retaining walls, basically double the current width of Pym Street. How many of the properties that "need access" would need to be acquired and destroyed to provide it? I get a total of about ten from Google Maps.

As I've done that maths, I realise why they have gone to the effort of lowering the road, besides the noise attenuations.

Websites used to prepare these estimates:

• https://www.google.com.au/maps/@-34.882 ... !1e3?hl=en location
• https://www.brainline.org/article/wheel ... nformation Slope
• https://www.infrastructure.sa.gov.au/__ ... tts_Rd.pdf Widths
• https://www.dpti.sa.gov.au/__data/asset ... n_2_33.pdf clearance
• https://www.tccs.act.gov.au/__data/asse ... ridges.pdf depth

[how good is he]

Great work SBD and makes sense why its not feasible and won't be done. I think therefore they should start preparing a plan to remove the traffic lights/intersection at Pym St with new bus routes now.

[Aidan]

Not so fast, how good is he!

SBD, your calculations are too conservative. There's no good reason for the bridge to be over 2m thick. We should reject the option of a bridge with longitudinal beams beneath the deck because that would make the bridge deck too high. Instead we can have one supported by beams (or even just trusses) at the sides.

Pym street does not currently have bike lanes, so why are you treating them as essential? Why not just lower the speed limit so the bikes fit in better with normal traffic?
If having a dedicated cycleway over South Road is the objective, why not have a bicycle bridge further south, utilizing the acoustic mounds between Lamont and Overland to provide a gentle gradient?

A width of 3m each way should be sufficient for the traffic lanes, particularly if the speed limit is low.
The footpath would need to be at least 1.2m wide, though a single one should be sufficient and if a second one is provided it need not be as wide.
Safety barriers would also be needed, but no space need be dedicated to retaining walls as the deck could have cantilevered edges.

Other things that need to be considered are:
How much could the level of Pym Street be raised while still providing good access to the houses along it?
How deep are the utilities under South Road? Even if the surface can't be moved much, it doesn't mean it can't be moved at all. And if they're all shallow, a box culvert underpass could be a good alternative to a bridge.

[SBD]

Not so fast, how good is he!

SBD, your calculations are too conservative. There's no good reason for the bridge to be over 2m thick. We should reject the option of a bridge with longitudinal beams beneath the deck because that would make the bridge deck too high. Instead we can have one supported by beams (or even just trusses) at the sides.

Pym street does not currently have bike lanes, so why are you treating them as essential? Why not just lower the speed limit so the bikes fit in better with normal traffic?
If having a dedicated cycleway over South Road is the objective, why not have a bicycle bridge further south, utilizing the acoustic mounds between Lamont and Overland to provide a gentle gradient?

A width of 3m each way should be sufficient for the traffic lanes, particularly if the speed limit is low.
The footpath would need to be at least 1.2m wide, though a single one should be sufficient and if a second one is provided it need not be as wide.
Safety barriers would also be needed, but no space need be dedicated to retaining walls as the deck could have cantilevered edges.

Other things that need to be considered are:
How much could the level of Pym Street be raised while still providing good access to the houses along it?
How deep are the utilities under South Road? Even if the surface can't be moved much, it doesn't mean it can't be moved at all. And if they're all shallow, a box culvert underpass could be a good alternative to a bridge.

You may be right that the calculations are too conservative. Bridge thickness was derived from the reference which provide an estimate of thickness as a proportion of length, and done with an assumption of a single clear span between abutments.

I regarded the bike lanes as essential as the current plan has a bike/pedestrian crossing in the vicinity. The concept video actually shows some pretty dangerous turns to get to/from the bridge crossing from/to Pym Street or the South Road bike lanes, so I would expect it to be built somewhat differently. I don't think that removing the bike lanes in my analysis would make the bridge narrow enough for both the access roads and bridge to fit in the current footprint though.

You don't actually need to raise Pym Street very much at the ends of the driveways if the intent is to also keep the left-in/left-out accesses. An alternate design would be to use one street for the overpass and the next one (eg Royce/Hotchkiss) for the South Road accesses.

[Aidan]

You may be right that the calculations are too conservative.

Of course I'm right, and I've explained why. Site constraints should not be ignored.

Bridge thickness was derived from the reference which provide an estimate of thickness as a proportion of length, and done with an assumption of a single clear span between abutments.

The problem was you assumed a general purpose type of bridge rather than one designed for the specific purpose. I suggest you read http://www.steelconstruction.info/Half-through_bridges to get an idea of the alternative configuration I'd envisaged.

I regarded the bike lanes as essential as the current plan has a bike/pedestrian crossing in the vicinity.

And yet the concept video DOES NOT INCLUDE bike lanes.
Anyway, what's essential should depend on what's needed (like the bus route) not what's in the current plan.

The concept video actually shows some pretty dangerous turns to get to/from the bridge crossing from/to Pym Street or the South Road bike lanes, so I would expect it to be built somewhat differently. I don't think that removing the bike lanes in my analysis would make the bridge narrow enough for both the access roads and bridge to fit in the current footprint though.

This isn't about keeping the existing footprint; it's about minimizing footprint expansion so that no more houses on Pym Street need be demolished (though some front gardens would shrink).

You don't actually need to raise Pym Street very much at the ends of the driveways if the intent is to also keep the left-in/left-out accesses. An alternate design would be to use one street for the overpass and the next one (eg Royce/Hotchkiss) for the South Road accesses.

My concern is not the South Road accesses, but access to the houses on Pym Street — for which retaining the South Road accesses is likely to be the best solution (on 3 sides at least, not sure about NE). And the option of raising Pym Street is to shorten the section that would need an expanded footprint.

[ChillyPhilly]

Bridge to Ayliffes Road.

.

[Honey of a City]

Any news on when the landscaping is going to commence? The Port Rd/South Rd intersection is a pretty grim wasteland right now. The crooked goal post sculpture installation doesn’t help much either.