[U/C] M2 North-South Motorway

[rev]

The Western Ring Road goes mainly through industrial estates and has plenty of space on either side. Our Motorway will not.

I suggest you look at the Western Ring Road on Google Maps, you'll find there's more residential then industrial.

What does "space" on the sides have to do with it?


What space? 100km/h..residential on either side too.
This is one section, but no need to look at the rest because this proves my point. Greater speed limit, bordering residential areas, sunken freeway as well.

[Norman]

More space means there is more run-off if you come off the road instead of slamming into a concrete wall or barrier running along the motorway. It's the same on the West Gate Freeway, where the speed limit is 80.

Additionally, the Monash Freeway, including the Citylink tunnels, are all 80km/h for around 16km. Again, it's a trenched and tunnelled freeway. Nothing new here.

[Nathan]

Never seen the three other options before - very interesting! Thank you!

The funny thing is I did a Google search to find the reference and the image came from... this forum

[rev]

More space means there is more run-off if you come off the road instead of slamming into a concrete wall or barrier running along the motorway. It's the same on the West Gate Freeway, where the speed limit is 80.

Additionally, the Monash Freeway, including the Citylink tunnels, are all 80km/h for around 16km. Again, it's a trenched and tunnelled freeway. Nothing new here.

Let me point you in the right direction to where your point about space/speed is shown to be void, rather then repeating my self.

viewtopic.php?f=9&t=3172&start=1230#p134249

[Norman]

The image doesn't show up, sorry.

[ChillyPhilly]

Will a 'lower' speed limit along the future Motorway help to increase road capacity?

[rev]

The image doesn't show up, sorry.

Fair enough, damn postimage.
Anyhow, the image shows a section of the Western Ring Road through a residential area. It is a lowered section, a trench like our T2T will be. It is 100kmh. There is obviously no run off room like an open country highway. It's a freeway through suburbia at 100kmh. That was my point.

[claybro]

For what it's worth, I think 80km/h on an urban freeway is adequate, and certainly for our trench. I can confirm the Kwinana and Mitchell freeways here in Perth are mostly 100km/h, with the Southern (Kwinana) Freeway become a bit of a killing field. Too much traffic, lots of merging, too close together travelling too fast = lots of bad pileups during busy times. At the very least, variable speed limits via the electronic signs are the way to go.

[drsmith]

The Western Ring Road image above to me looks like it has an emergency stopping lane although to be honest, I wouldn't like to be broken down there and unable to climb the wall to escape potential stray vehicles doing 100 km/h.

The Torrens to Torrens trench doesn't appear to have emergency stopping lanes from the video animation. Another factor in relation to the posted speed limit is the ramps. Longer ramps would be required for acceleration/deceleration with higher speed and in regards to that, stopping distance increases in proportion with the square of the speed.

[The Scooter Guy]

A similar thing to my previous mentioning!
https://au.news.yahoo.com/video/watch/2 ... nex/#page1

[ChillyPhilly]

The Western Ring Road image above to me looks like it has an emergency stopping lane although to be honest, I wouldn't like to be broken down there and unable to climb the wall to escape potential stray vehicles doing 100 km/h.

The Torrens to Torrens trench doesn't appear to have emergency stopping lanes from the video animation. Another factor in relation to the posted speed limit is the ramps. Longer ramps would be required for acceleration/deceleration with higher speed and in regards to that, stopping distance increases in proportion with the square of the speed.

I believe the Gallipoli Underpass is engineered for only 60km and not more.

[Norman]

Well, they probably need to modify the entry and exit paths of the underpass anyway.

[rubberman]

I believe the Gallipoli Underpass is engineered for only 60km and not more.

That is possibly so, but if you compare that to the Goodwood Road underpass, which certainly feels ok at 60km/hr, it's probably a very conservative design.

[rockthenation]

I think 60km/h for the Gallipoli underpass is definitely conservative.
Drove past T2T yesterday, looks like the remaining properties on the corner of South & Grange Rds have been acquired.

[neoballmon]

I would assume 100 is more than possible safely through the underpass. But for trucks using the ramps, 60 is probably the fastest they can slow down safely at, hence the 60 design speed.