Australian Motorways

[Big L]

I broadly agree with your post, but I wanted to reply to this bit because your item 2 has come up a few times in other posts you've made too. In the UK, it is decidedly rare for a two-bridge roundabout interchange to have curved bridges. The roundabout is almost always oval shaped so that the bridges are straight. IME curved bridges on junctions of this type are more common in European versions of the junction.

You are right, and I stand corrected: UK curved GSR bridges are rare indeed. I just scanned right along M1 and M4, and the only ones I found are at M1 Lofthouse, where there are four of course (and their curvature is so slight that they may as well have been straight). As you point out, I've harboured this false assumption for a long time. I suppose I should edit my praise of dumbbells!

The use of straight alignments on two bridge roundabouts is why most of them have high speed problems and end up signalised. The curved bridges you lament would actually be safer.

Like the new curved* bridges at M6 J10.
*Bridges are, I suspect, straight; the road is curved.

[Peter Freeman]

Like the new curved* bridges at M6 J10.
*Bridges are, I suspect, straight; the road is curved.

My scan along M1 and M4 found only 4 actually-curved bridges, but there are multiple occurrences of straight bridges with curved roads across them, similar to new M6J10. This makes eminent sense: a straight bridge is easier to design and build - and, back to my original point, is easier to re-use.

[Gav]

Like the new curved* bridges at M6 J10.
*Bridges are, I suspect, straight; the road is curved.

My scan along M1 and M4 found only 4 actually-curved bridges, but there are multiple occurrences of straight bridges with curved roads across them, similar to new M6J10. This makes eminent sense: a straight bridge is easier to design and build - and, back to my original point, is easier to re-use.

may be easier, but its a lot more costly - that junction the bridge is massive in terms of size in relation to the actual lanes crossing it.

[Peter Freeman]

Yesterday Australia experienced its worst road accident (number of fatalities) since 29 years ago. It ranks 7th of all time. Ten deaths, many injured.

A chartered bus, carrying 35 guests after a wedding reception at a winery, rolled over onto its left side at 11:30pm at a roundabout. It approached the roundabout southbound, to turn right (westbound) onto a motorway, but too fast, ending up on the armaguard at the very top of the on-ramp. No other vehicle involved. It's reported that there was fog (it's wintertime here), but I doubt that as a cause. Witnesses have said that the driving was 'erratic'. Breath test results have not been released. The 58-year-old driver has been charged with ten counts of 'causing death by ...', plus 'negligent driving', and more.

This location, on the M15 Hunter Expressway, is one of our few UK-style GSR's (elevated, two-bridge)-
https://www.google.com.au/maps/@-32.668 ... ?entry=ttu

Edit: Survivors witness that ten minutes of reckless driving preceded the crash, and during that period the driver reminded passengers, over the PA, to wear their seat belts.

[Peter Freeman]

Here's an update video on the Westgate Tunnel project in Melbourne Australia (my previous post was in this thread on 28-10-2020). This video focuses on the city-end dispersal of tunnel traffic. It has many shots of current traffic conditions, some of construction progress, and some that are modellings of the new arrangements. I think it's difficult to follow for outsiders, and too hard for me to explain further, but still, you'll get the feel for what's going on.

As usual, you'll be able to spot many variations from, and contrasts to, UK motorway design practise, such as M2M metering. Included is a merge of 3+2+2=4 lanes (facilitated by two parallel meters).

The Youtube video is called 'Westgate Tunnel Series Episode 6'. You could search for the previous five episodes if interested.

Completion is set for 2025.

https://www.youtube.com/watch?v=Oyu-XM64eJM

[Peter Freeman]

One of my favourite stretches of motorway is the M1/M3 Pacific Motorway, connecting Gold Coast to Brisbane. It's fairly straight and flat, not scenic, but it has a certain flair and dynamic excitement to it. Mainly, I like its interchanges - their frequency and the eclectic mix of types.

I've analysed the mix by classifying each interchange along the 100km between the Tweed River bridge and the Brisbane River bridge. There are 44 interchanges, with an average spacing of 2.3km.

This is the result -
9 Diamond
6 Dumbbell
3 Semi-dumbbell
3 Half diamond
3 Fork
2 Complex fork
2 GSR
2 Semi-folded diamond
1 Semi-folded dumbbell
1 Semi-folded half dumbbell
1 Folded diamond
1 DDI
1 SPUI
1 Trumpet
1 Dogbone
1 Two-way fork
6 Unclassified

That's a diverse inventory. As expected for Australia, the most frequent type is diamond, but only just. Unusually, it includes two UK-style grade-separated roundabouts (multi-armed, with the roundabouts at ground level). Six interchanges could not be classified, though they're not 'spaghetti'. At a push, they could be regarded as irregular diamonds.

In addition, out of all these interchanges, only a few have the standard shape. Most have at least something that's non-standard. Not only do the free-flow forks have 'extras' attached, but even the trumpet does! The GSRs and standard dumbbells are the main conformists.

My travels on this stretch have always been off-peak, encountering low traffic density and therefore enjoyable, but much of the route has, or had, a reputation for congestion. The close junction spacing would be a contributor to that. My recent impression is that the situation has been eased by a large-scale upgrade program, including widenings to D4 and D5, and provision of C/D lanes and some braiding.

Further M1 traffic increase is forecast though, so a parallel D3 motorway, the Coomera Connector, is planned just a few km to its east. Its function will be to carry local traffic, with long-distance traffic remaining on the M1. Stage 1 is under construction. Info -
https://www.tmr.qld.gov.au/projects/pro ... -connector

EDIT: corrected D6 to D3.

[jackal]

Thanks Peter, that's interesting. Where's the trumpet?

Looks like the connector will be D2 on opening with future proofing for D3. Map for stage 1 north (central and south are not yet released): https://www.tmr.qld.gov.au/_/media/proj ... tage-1.jpg

[Peter Freeman]

Oops! D6 would be quite spectacular right through there! I meant D3. Corrected now in my earlier post.

Yes, Stage 1 is to be initially D2. Short-sighted I think, but it will be ok for a few years. That detailed map (which covers a very short length of motorway) suggests to me that at least part of it may have the third lane paved, but hatched out.

Brisbane will host the Olympic Games in 2032, and venues will be on the Gold Coast as well as in Brisbane There is talk of major projects being brought forward, so it is likely that CC further stages will arrive by then.

[Peter Freeman]

Thanks Peter, that's interesting. Where's the trumpet?

That's a very good question. I think it was (note the tense) exit 89, on the south side of Gold Coast, 2km east of exit 87, the DDI that used to be a GSR. 89 is currently a two-sided LILO according to G.Maps, but in 2021, when I actually did this classification, it was more like a trumpet (history is on GE). Even then, 'trumpet' wasn't quite literal. That's the thing about these interchanges: there's hardly any that are standard shapes!

The upgrade at exit 89 is not complete, and G.Earth Sept 2023 contradicts G.Maps. This project video (at 25s to 45s *) shows it ending up as a simple signalised diamond, so I think there will be further temporary arrangements to switch through before the final config is reached -
https://www.youtube.com/watch?v=OG_HvbfQKn8&t=2s

My list might have slipped out-of-date on the dumbbells too, as current and recent upgrades are eliminating them. I might soon post about them in AU Road Markings topic.

* edited to add video window's start and end times

[jackal]

Cheers - that explains it!

[Peter Freeman]

Coomera Connector Stage 2 flyover (artist's impression) is available. Video shows D3, but likely D2 initially, as with Stage1. It also confirms that the northern terminus, at Pacific and Logan Motorways, will be 6/8 movements.

https://www.youtube.com/watch?v=pRckRAd0jjk&t=0s

[jackal]

It also confirms that the northern terminus, at Pacific and Logan Motorways, will be 6/8 movements.

https://www.youtube.com/watch?v=pRckRAd0jjk&t=0s

It's interesting that it's an offside/TOTSO configuration - I guess this is because the Pacific Motorway movements will be dominant though it might just be easier to fit onto the existing interchange.

They also seem to be excising the local movements from the southbound to westbound turn, I suppose for buildability or to eliminate the current weaving space here: https://www.google.co.uk/maps/@-27.6883 ... ?entry=ttu

Curious that the other end of the scheme won't connect to the Pacific Motorway and just staggers onto the at-grade Nerang Broadbeach Road around here: https://www.google.co.uk/maps/@-27.9978 ... ?entry=ttu

[Peter Freeman]

It also confirms that the northern terminus, at Pacific and Logan Motorways, will be 6/8 movements -
https://www.youtube.com/watch?v=pRckRAd0jjk&t=0s

It's interesting that it's an offside/TOTSO configuration - I guess this is because the Pacific Motorway movements will be dominant though it might just be easier to fit onto the existing interchange.

Coomera Connector northern terminus - Copy.JPG

The Coomera-Brisbane turn will definitely dominate. Also, as I've opined before, AU will accept an offside exit if it's anywhere close to balanced (subject to weaving elimination). See M79/M2 diverge in Melbourne -
https://www.google.com.au/maps/@-37.732 ... ?entry=ttu

They also seem to be excising the local movements from the southbound to westbound turn, I suppose for buildability or to eliminate the current weaving space here: https://www.google.co.uk/maps/@-27.6883 ... ?entry=ttu

I hadn't noticed that. It must be for weaving elimination, since it could easily have been retained. I notice an extra local road (or is it just a bike/pedestrian track?) spanning the M1 at the south-west edge of your posted image, though it might not replicate that lost movement.

Curious that the other end of the scheme won't connect to the Pacific Motorway and just staggers onto the at-grade Nerang Broadbeach Road around here: https://www.google.co.uk/maps/@-27.9978 ... ?entry=ttu

Yes, that struck me too, very early on, and I wondered who else it would jar on! You might say that it's rather 'Australian' though ...? It's reminiscent of the way Melbourne's M3 ends, ridiculously, on a city street, because the planned westward continuation was irrevocably cancelled on amenity/liveability grounds.
(But that will, one distant day, be fixed by tunnelling. M3 image -
https://www.google.com.au/maps/@-37.795 ... ?entry=ttu)

The reason at Coomera, however, is functional. Although it was for some years referred to as 'the 2nd M1', it's not intended to be an M1 bypass. It's an internal road for GC's northern suburbs' use. By the time it reaches Nerang-Broadbeach Road, most traffic will have dispersed into GC. Even so, I don't like it either! There are opportunities, a few km north, to merge it back to M1, as well as meeting NBR.

[jackal]

The thought about buildability was that the local ramp that currently feeds into the weaving space is right in the way of the viaducts for the southbound connector.

Why do you say M2/M79 is an offside exit?

[Peter Freeman]

^ OK, going by the road numbers, it's not an offside, since M2 begins in the city and turns right at that interchange (it's a TOTSO). But really, especially in the longer term, straight-on is the major route (lots of growth up that NW way), despite the right-diverge leading to the Airport and optionally to M31. Calder Fwy/Hwy runs for 600km NW.

It would make more sense for the Tullamarine Freeway up to that point to be numbered M79 instead of M2, and to be named Calder Freeway.

(William Calder was a pioneer road administrator in Victoria. Almost our equivalent of Lancashire's Drake)

(Edited mainly for spelling mistakes. It's a pity the forum doesn't have a spell-checker).

[Peter Freeman]

The thought about buildability was that the local ramp that currently feeds into the weaving space is right in the way of the viaducts for the southbound connector.

Ah, yes, and so probably a good pragmatic removal. Mind you, it's surprising how cleverly viaducts can be supported on widely-spaced uprights and a lintel.

[jackal]

^ OK, going by the road numbers, it's not an offside, since M2 begins in the city and turns right at that interchange (it's a TOTSO). But really, especially in the longer term, straight-on is the major route (lots of growth up that NW way), despite the right-diverge leading to the Airport and optionally to M31. Calder Fwy/Hwy runs for 600km NW.

It would make more sense for the Tullamarine Freeway up to that point to be numbered M79 instead of M2, and to be named Calder Freeway.

(William Calder was a pioneer road administrator in Victoria. Almost our equivalent of Lancashire's Drake)

(Edited mainly for spelling mistakes. It's a pity the forum doesn't have a spell-checker).

Ah I see - you mean offside in terms of volumes. That's not something I would consider to be a factor in terms of whether something is offside or not.

It's actually surprisingly complicated to define an offside diverge. One definition is limited to simple offside diverges - that isn't the case with the example in Queensland, where there will be a lane drop.

What I have in mind, I think, is whether the junction comports with a classical and obviously non-offside design like a diamond, trumpet, cloverleaf, stack, etc (a very long list). To me the Victorian example just looks like a classical fork and therefore not offside (if you ignore the extra carriageways as I think we both are).

To complicate things further, I don't think it's a TOTSO, which to me concerns the road number rather than the physical properties that offside refers to.

[Peter Freeman]

OK, we're very much into a definitional/semantic area. We can simply call it a fork - except that it's not simple, owing to the auxilliary lanes/carriageways.

If you use streetview and virtually drive it, you'll feel/see that westbound M79 is a 'drive-straight-on' non-action, while M2 swings (albeit very gently) through a 90 degree right curve - TOTSO ?!

(Inserted by edit 21-11-2023: Prior to a 2007 round of 'Tullamarine Freeway Upgrade', M2 simply branched northwards off (what I would like to call) M79 by a trumpet. Thus, there was a standard left-side diverge (with a single lane drop). Half of the bridge for this trumpet is now re-used by the westbound C/D carriageway that begins at the Bulla Road interchange and ends at English Street. This history can be seen on GE from 2001 to 2005, and the disused loop of the trumpet is clearly visible on GE and GMaps even now. So, the initial form was not an offside diverge, or a fork, but was more decidedly TOTSO).

Anyway, the good thing is that it flows well, and I rarely see any issues of late weaving, driver uncertainty over lane selection, etc.

[Peter Freeman]

Animation showing construction of the main elevated part of Melbourne's Westgate Tunnel Project. This component, like the tunnels, is now substantially complete - surfacing and finishing works still to do.
https://www.youtube.com/watch?v=0DDSOrJb9Co

[Peter Freeman]

Fig Street Ramp. See on this animation how a new ramp braid on Sydney's Western Distributor Motorway, city-bound, will be threaded between multiple piers that support the motorway lanes above. This probably should have been built-in from the start, but better late than never.
https://www.youtube.com/watch?v=cgrYPtwA0Pc&t=0s

The Western Distributor, in-place for many years to carry M4 traffic to the Harbour Bridge, Cross-City Tunnel and the CBD, is receiving a series of capacity upgrades following the Rozelle Interchange completion. Fig Street Ramp is one. Most are small-scale intersection works. Info here -
https://www.transport.nsw.gov.au/projec ... or-network