[COM] Southern Expressway Duplication | $445m | 22km

[crawf]

First steps for $455m Southern Expressway project
http://www.adelaidenow.com.au/news/sout ... 5882005444

THE State Government tomorrow will kickstart the $455 million Southern Expressway duplication and call for tenders for a detailed planning study.

Transport Minister Patrick Conlon said the study marks stage one of the expressway's duplication and would formalise the alignment of the upgraded road.

Many of the existing nine road bridges and five footbridges would have to be rebuilt or significantly altered during the duplication.

Mr Conlon said the successful tender applicant would have to address a series of environmental issues, including noise, flora and fauna, air and water quality and Aboriginal heritage.

Interchanges will be built at the southern and northern ends of the project, with additional ramps added to some existing interchanges.

The planning study contract will be awarded in August. Construction is scheduled to begin late next year and expected to be completed in 2014.

[iTouch]

sweeettt

[drsmith]

Any news on what the South Road/Sturt Road intersection will look like when this is all done ?

[Stubbo]

I am glad this is going ahead, Living in Mitchell Park it is great to have more transport options besides South and Londsale.

There were plans to put an underpass in at Sturt and South Rds but originally this was the third underpass to be built after ANZAC and Port Rd so not sure where it sits in the scheme of things now. I would hope it will be on the 'drawing board' within the next 10-15yrs.

I have no idea what there planning for the Castle Plaza section though. Now there is more land available around the end of Raglan Ave with the removal of Hills, it makes sense to me to realign Raglan to Edward Street and then have one intersection to work with instead of two. This would also allow Castle Plaza to expand on a single site.

[ac83]

Hi all,

Driving to work yesterday and today I saw some workers with theodolites around the Darlington interchange. I'm assuming this is all part of the duplication plan. Still can't believe this is actually going to happen. I remember last year when I went to the traffic management centre in Norwood for an open day and the manager there was saying it will never happen!

Why the liberals didn't make the briges wider back then for future proofing I'll never know!

Azz

[muzzamo]

Why the liberals didn't make the briges wider back then for future proofing I'll never know!

I honestly think they *did* make them future proof and there is some cheap political point scoring going on instead.

The bridge in the picture below currently spans 1 pedestrian path, 2 emergency lanes and 1 veloway.

If you have a look at the attached photoshop you can see that it will probably be able to do 3+3 without any real issues. The emergency lanes would resume either side of the bridge. Unfortunately the veloway would no longer be grade separated but such is life.

The expressway overpasses, on the other hand, eg field river and Sherrifs road, but excluding lander Road because I think it is wide enough and was constructed differently, were not built to accommodate the extra lanes because scaling to twice as many lanes would probably double the cost of the bridge, and there was no real benefit to doing it back then compared to just building an extra bridge now

Click the images below to enlarge.

expressway-original.jpg (116.22 KiB) Viewed 2785 times

expressway-new.jpg (114.12 KiB) Viewed 2785 times

[muzzamo]

As above, the sheriffs road overpass would need to be duplicated. There would have been little benefit in making this wider to begin with.
Click the images to enlarge.

sherrifs old.png (632.24 KiB) Viewed 2785 times

sherrifs new.png (611.2 KiB) Viewed 2785 times

[Paulns]

I hope they future proof this expressway by making it 3+3 each way. The Southern Suburbs are only going to grow.

[Archer]

muzzamo, as you've shoun in the pictures above, provided the veloway is removed (I don't think that will go down well), there is physically space in the bridges for duplication, but what impact would this have on the speed limit?

I'm sure there would be safety standards for a road signposted at 100 Km/h that requires a minimum distance between the edge of the road and any obstacles on the side of the road. From the looks of the pictures you've provided above, it's going to be a tight squeeze and these saftey standards (if they exist) would be at risk......?

Would the speed limit need to be lowered to allow for the bridge supports to be that close to the expressway? or do such safety standards not exist?

[muzzamo]

Would the speed limit need to be lowered to allow for the bridge supports to be that close to the expressway?

My gut feeling is that if you use concrete barriers etc to protect the bridge etc it shouldn't matter.

Besides, as per my illustration, there is a few meters left over in the overall design, particularly if you use a thin concrete median.

All things considered though, the government may decide to duplicate the bridges anyway, which would mean grade separation of the veloway as well as future proofing for 3+3 and 4+4.

[Archer]

Would the speed limit need to be lowered to allow for the bridge supports to be that close to the expressway?

My gut feeling is that if you use concrete barriers etc to protect the bridge etc it shouldn't matter.

Besides, as per my illustration, there is a few meters left over in the overall design, particularly if you use a thin concrete median.

All things considered though, the government may decide to duplicate the bridges anyway, which would mean grade separation of the veloway as well as future proofing for 3+3 and 4+4.

I was more concerned with the increase possibility of fatal car accidents rather than damage to the bridge. Given the push to try and reduce our road toll it seems silly to have such a solid object so close to a high speed roadway.

I agree though that I feel they will probably duplicate the bridges, which I think would produce a better and safer road in the end.

[Aidan]

I hope they future proof this expressway by making it 3+3 each way.

Would that be 3+3 on the northern section (as far as Panalatinga Road)? If so, that's a pretty safe bet - the government is unlikely to want to narrow it.

Or do you mean 3+3 on the southern section (all the way to Hackham)? If so, 3+3 lanes would soon become inadequate for the northern section, so it wouldn't be futureproofing at all.

The Southern Suburbs are only going to grow.

But is widening the Southern Expressway really the best way to accommodate that growth?

Would the speed limit need to be lowered to allow for the bridge supports to be that close to the expressway?

My gut feeling is that if you use concrete barriers etc to protect the bridge etc it shouldn't matter.

Concrete barriers would not make it sufficiently safe. But wire rope safety fences might. I've noticed these have already been installed in several locations along the SE Freeway.

When the southern section of London's M25 was widened, they didn't widen the bridges. Wherever a bridge interrupted the emergency stopping lane, they put signs up saying NO HARD SHOULDER which was crystal clear to the locals but confused some visitors from overseas.

Besides, as per my illustration, there is a few meters left over in the overall design, particularly if you use a thin concrete median.

All things considered though, the government may decide to duplicate the bridges anyway, which would mean grade separation of the veloway as well as future proofing for 3+3 and 4+4.

It really depends on whether the solution is intended to be temporary or permanent. It there are big changes that may or may not be made, such as constructing an exit at Majors Road, a temporary solution might be better value. Grade separating the cycleway would be much cheaper than another road bridge.

[drsmith]

If you have a look at the attached photoshop you can see that it will probably be able to do 3+3 without any real issues. The emergency lanes would resume either side of the bridge. Unfortunately the veloway would no longer be grade separated but such is life.

The northbound carriageway in the first image overlaps the western bridge abutment by some margin so, not only would the emergency lanes go, the actual traffic lanes would also have to be narrowed. If done it would not be without precedent . In Perth, the southbound lanes on the Narrows Bridge (Kwinana Freeway) were narrowed from 3.5m to 3.4m to make way for the southbound track of the Perth/Mandurah railway. The original bus lane upon which the railway track was laid was not quiet wide enough for that purpose.

In Perth there are many examples of no emergency lane on freeway/highway bridges where the freeway/highway is bridged over the crossing road. A metal barrier in the form of a fence however is less likely to result in serious injury/loss of life than high speed contact with a solid concrete bridge abutment.

If the government thoughut it would get away with that to save costs then it would but there is no way they will try to squeeze 6-lanes of traffic under that bridge. My guess is that bridge will either have to be duplicated or demolished (more likely I think) and a new one constructed to adequately accomodate both carriageways.

[muzzamo]

If the government thoughut it would get away with that to save costs then it would but there is no way they will try to squeeze 6-lanes of traffic under that bridge. My guess is that bridge will either have to be duplicated or demolished (more likely I think) and a new one constructed to adequately accomodate both carriageways.

The quick photoshop that I did allowed for a fairly large median though - it would seem that with a reduced median there would be adequate room.

[muzzamo]

Grade separating the cycleway would be much cheaper than another road bridge.

Or, what I think is more likely to happen, which is to remove the grade separation of the cycleway all together, which would be disappointing but fair.