Gauteng Freeway Improvement Project

[jackal]

I thought people might be interested in this huge South African scheme. The first stage, which will complete in the next few months, involves widening 155km of motorway. This includes bringing the entirety of the Johannesburg ring road (N1, N3, N12) to at least D4M standard, the main Joburg to Pretoria freeway (N1) to D5M, and the secondary Joburg to Pretoria freeway (R21) to D4M.

Also included in the first stage are 34 major junction improvements, highlights of which are a direct connector replacing a loop at the Flying Saucer interchange (N1/R21), a second direct connector being added to Gilloolys Interchange (N3/N12), and Allandale Interchange (N1/M39) being changed from a bog standard parclo to an unusual full freeflow design. Elsewhere extra slips and conversion of diamonds to single-point interchanges seem to be in fashion.

Planning up to 2020 includes a further 223km of widening, more junction improvements, and 158km of brand new motorway. Ultimately this would add a third freeway between Joburg and Pretoria, a second ring to Joburg's already impressive freeway network, and just for good measure, outer eastern bypasses for both Joburg and Pretoria:



Now you might ask how the National Roads Agency think they can afford all of this. The answer is that tolling is to be introduced, using gantry mounted sensors, cameras, and electronic tags, so no booths are needed as found elsewhere in South Africa. The rate is rumoured to be 50-65c (about 5p) per km, and all funds raised are ringfenced for the tolled network.

Here's a higher resolution map, detailed description, and random selection of (badly presented, alas) junction designs. Enjoy!

[signol]

Thanks for this, I knew something about it (my brother in law and his family live in Centurion) as we've visited a few times.
Last visit in October 2010 I didn't see much work on the N1 - but the D2 R21 is being widened, but it does seem to be overkill.
Also the tolling may seem to be a way to reduce congestion, alongside the construction of the Gautrain (which will be complete this year), as the N1 is allegedly the busiest road in Africa...
The tolls have been calculated to approximate the new train fare, to make the train even more attractive.

signol

[Vierwielen]

Last visit in October 2010 I didn't see much work on the N1 - but the D2 R21 is being widened, but it does seem to be overkill.
signol

The R21 is the main road between Pretoria and Johannesburg International.

[signol]

Last visit in October 2010 I didn't see much work on the N1 - but the D2 R21 is being widened, but it does seem to be overkill.
signol

The R21 is the main road between Pretoria and Johannesburg International.

Which is why I was using it - to get to and from Centurion

signol

[jackal]

Thanks for this, I knew something about it (my brother in law and his family live in Centurion) as we've visited a few times.
Last visit in October 2010 I didn't see much work on the N1

I was on the N1 in December 2010 and most of the work seemed to be finished. Google street shows some rather more conscipuous works, probably from early 2010.

- the D2 R21 is being widened, but it does seem to be overkill.

Google street again has some nice shots, including the new direct connector for R21Nb->N1Eb, which replaces the previous loop and C/D lane set up. (Here's a similar upgrade for N12Wb->N3Nb just after completion.)

As for the R21 upgrade being overkill, there are plans to build a new freeway through Germiston (!), i.e. from the N12/R21 junction down to the N3/M2 junction (see south-eastern red-dotted line on map upthread). So they might have built in extra capacity in the recent upgrade for when the southern end is linked up.

There are also longer term plans to build a new freeway from the R21, past Benoni and Boksburg, over the N17 and onto the N3. See the south-eastern red dotted line on slide 11 here (other slides show interchange designs). While that would take traffic away from the southern end of the R21, it would add traffic to most of it.

[signol]

As for the R21 upgrade being overkill, there are plans to build a new freeway through Germiston (!), i.e. from the N12/R21 junction down to the N3/M2 junction (see south-eastern red-dotted line on map upthread). So they might have built in extra capacity in the recent upgrade for when the southern end is linked up.

Well, they've got to do something with all those new train fares they are collecting! R100 for a single ticket to the airport...

signol

[booshank]

Upgrades to the Elands Interchange (N3-N12) too.

This also seems to include direct links between the N12 and N17 so that traffic wanting to go from the one to the other won't have to go via the Rand Airport (N3-N17) interchange:-

[jackal]

I had a look at that drawing when I made the original post and decided the most interesting things were the new links between the N12 and N17 (which should really have been there from the start). I thought the thick blue line was just a replacement for the existing direct connector, to allow the N3 mainline to be continuous.

But looking at it again I think it's a similar upgrade to the Hospital Bends upgrade in Cape Town, where the new direct connector is in addition to the old one. The idea is presumably to reduce weaving on the N3/N12 mainline by allowing N3 traffic to 'pre-select' whether they want to head straight on at the next interchange (N3/M2 at Germiston) or turn onto the M2.

If that's right, that is, as far as I know, a unique South African solution to weaving on high volume freeways. The only thing I've seen elsewhere that is at all similar is the dedicated ramp for high occupancy lanes in California. The usual solutions for weaving are braiding and C/D lanes but these seem to be avoided in SA (excluding some limited examples, such as eastbound on the N1 in Cape Town and numerous cloverleafs).

[booshank]

But looking at it again I think it's a similar upgrade to the Hospital Bends upgrade in Cape Town, where the new direct connector is in addition to the old one. The idea is presumably to reduce weaving on the N3/N12 mainline by allowing N3 traffic to 'pre-select' whether they want to head straight on at the next interchange (N3/M2 at Germiston) or turn onto the M2.

If that's right, that is, as far as I know, a unique South African solution to weaving on high volume freeways. The only thing I've seen elsewhere that is at all similar is the dedicated ramp for high occupancy lanes in California. The usual solutions for weaving are braiding and C/D lanes but these seem to be avoided in SA (excluding some limited examples, such as eastbound on the N1 in Cape Town and numerous cloverleafs).

When I first saw the new De Waal Drive connector at Hospital Bend I couldn't work out what was going on, thinking 'it's on the wrong side of the road!' But it's an interesting and straightforward solution. I wonder why it hadn't been tried before? Just because it might confuse drivers, being 'on the wrong side'?

[jackal]

I think this design is usually more expensive than a braiding or C/D lane arrangement as there is more structural content (a long sweeping curve over the mainline rather than a simple slip-over-slip crossover or additional lanes and barrier). So that would explain why this isn't the usual weaving solution.

The explanation for why it has been selected is probably a little different in the two cases. At de Waal Drive I think there simply isn't the space on that side of the road for braiding or C/D lanes.

There is the space around the N3 but there is so much distance (1.5km+) between the N3/M2 and N3/N12 junctions that you'd have to build a long length of C/D lanes or extended slips for braiding. So the extra connector may actually be cheaper in this special case. Weaving is not generally an issue where junctions are so far apart but flows are unusually high here.

[booshank]

There certainly isn't any room next to Groote Schuur Hospital (btw, this was where the first heart transplant took place) and this section of road was fairly notorious for accidents due to a combination of a bend on a gradient and weaving.

There's also a collector-distributor system at the Umgeni Rd/Inanda Rd exit on the N2 in Durban. It was a pair of diamond interchanges close together on either side of the Umgeni River connected by four parallel bridges (two for the N2 and two for the collector distributors).

At the moment the southern diamond is being replaced by a system of semi-directional ramps and a loop:-

[jackal]

I'm not sure if those really count is C/D lanes as they don't connect to the mainline at either end. The upgraded road will be a bit more C/D like as the outercarriageways will be extended through the southern junction to merge with the mainline.

It's a somewhat extravagant upgrade for a diamond. It would make more sense if the direct connectors were leading onto the M19 to the west, which is grade separated as far as Pine Town, but that only gets a loop for one right turn and seems to have the other right turn removed altogether.

To the east the M19 doesn't get far before the at-grade junctions kick in. Are these being removed as well? If not it seems extraordinary that the road is thought worthy of a four-level interchange.

[signol]

There's also a collector-distributor system at the Umgeni Rd/Inanda Rd exit on the N2 in Durban. It was a pair of diamond interchanges close together on either side of the Umgeni River connected by four parallel bridges (two for the N2 and two for the collector distributors).

I've used that junction a lot (my in-laws live in Pinetown) abd boy does it stack up! But as noted, most traffic from Pinetown doesn't get much free-flow towards the CBD - but that traffic will mainly use the M13 and N3 further south. As it is, free-flow M19 - N3 north will bring major benefits. As long as the new "blue" M19 - N2 North slips don't end on the CD road, to be halted at the next half-diamond 200m further on...

signol

[booshank]

I'm not sure if those really count is C/D lanes as they don't connect to the mainline at either end. The upgraded road will be a bit more C/D like as the outercarriageways will be extended through the southern junction to merge with the mainline.

It's a somewhat extravagant upgrade for a diamond. It would make more sense if the direct connectors were leading onto the M19 to the west, which is grade separated as far as Pine Town, but that only gets a loop for one right turn and seems to have the other right turn removed altogether.

To the east the M19 doesn't get far before the at-grade junctions kick in. Are these being removed as well? If not it seems extraordinary that the road is thought worthy of a four-level interchange.

Google maps is outdated or inaccurate as the service roads connect to the N2 north of the Umgeni River.

Unfortunately SANRAL doesn't give its reasons for this design, but I would say that M19 west > N2 south (and vice versa) is probably the least used movement as it doubles back on itself. There is also a new crossing of the Umgeni River further inland which may handle traffic between Pinetown/New Germany and the N2 north of Durban.

Apparently there are also plans for freeflow upgrades to the Higginson (154), Edwin Swales (161) and Mount Edgecombe (182) exits and widening of the N2 and N3 to five lanes in each direction. The N2 Umgeni bridge has already been widened to accommodate this as part of the new interchange. Also there is talk of an upgrade to the EB Cloete interchange but I have not seen any concrete plans. It would make sense as most of the movements are only one lane ramps, but I'm not sure how it can be done without very major reconstruction.

If it's all true it seems as though it could rival the GFIP in scale.

[Vierwielen]

There's also a collector-distributor system at the Umgeni Rd/Inanda Rd exit on the N2 in Durban. It was a pair of diamond interchanges close together on either side of the Umgeni River connected by four parallel bridges (two for the N2 and two for the collector distributors).

I've used that junction a lot (my in-laws live in Pinetown) abd boy does it stack up! But as noted, most traffic from Pinetown doesn't get much free-flow towards the CBD - but that traffic will mainly use the M13 and N3 further south. As it is, free-flow M19 - N3 north will bring major benefits. As long as the new "blue" M19 - N2 North slips don't end on the CD road, to be halted at the next half-diamond 200m further on...

signol

Are there still loads of accidents in that area after the first rains of the season?

Many years ago I was a student at the University of Natal and at that time 45th Cutting (which is probably by-passed now) was a notorious black spot. Poorly maintained busses used to belch out black fumes that settled on the road. When the first rains of the summer came, the unburnt diesel would rise above the rainwater and create a lovely skating rink.

[signol]

Are there still loads of accidents in that area after the first rains of the season?

We've been stationary many times on the N2 north, crawling past accidents, on the way to Gateway. So probably yes...

signol

[jackal]

With all these developments it surprises me that there are no plans to connect the M4 and N3, or even the two ends of the (freeway) M4, together. In the former case we're only talking about a few hundred metres, so even though it would be complex in engineering terms it would not be prohibitively expensive. As things are the M4 and N3 get tantalisingly close, which must lead to the city centre being congested on account of traffic that doesn't even want to be there.

Apparently there are also plans for freeflow upgrades to the Higginson (154), Edwin Swales (161) and Mount Edgecombe (182) exits and widening of the N2 and N3 to five lanes in each direction.

This makes sense as these all cater for high quality grade-separated routes (Higginson has a couple of at-grade junctions near the interchange but is grade separated for some distance west of there). Indeed, as in the UK, there are large numbers of non-freeway 'expressways' in the Durban area - the M19, M25 and King Cetshwayo Highway also all fall into this category. This is not the case in Joburg or Cape Town, where the vast majority of grade separated roads are freeway. I'm not sure why this difference exists, but it makes Durban's network look at first glance much less developed than it actually is.

Also there is talk of an upgrade to the EB Cloete interchange but I have not seen any concrete plans. It would make sense as most of the movements are only one lane ramps, but I'm not sure how it can be done without very major reconstruction.

It looks like it may be possible to create two narrow lanes by eating up the shoulders and adjusting the barriers, but it would certainly be tight. I would certainly have thought that two lanes will be needed between the N3 West and N2 (both directions). It's pretty invariably the case that the turning movements from major intercity routes onto bypasses are the heaviest (hence why it is these movements alone which have been upgraded at Gillooly's, Flying Saucer, and at both ends of the N1 between Pretoria and Joburg).

If it's all true it seems as though it could rival the GFIP in scale.

I doubt the widening you mention adds up to 378km, and the Gauteng plans also include 158km of new freeway, and you haven't mentioned any of that for KZN. Of course, if the more ambitious elements of the Gauteng scheme get dropped and the KZN scheme is built in its entirety then it may be that the built elements are similar in scale.

[booshank]

With all these developments it surprises me that there are no plans to connect the M4 and N3, or even the two ends of the (freeway) M4, together. In the former case we're only talking about a few hundred metres, so even though it would be complex in engineering terms it would not be prohibitively expensive. As things are the M4 and N3 get tantalisingly close, which must lead to the city centre being congested on account of traffic that doesn't even want to be there.

There may be, but I have not come across any. A new flyover has been built at the end of the N3 though, which is visible under construction in Google satellite images. Perhaps a clue that this was once planned is that the N2 around the city is named the Outer Ring Road, which implies an unbuilt inner ring road. I suspect though that most traffic using the three freeways is heading to or from the city, not from one to another.

It looks like it may be possible to create two narrow lanes by eating up the shoulders and adjusting the barriers, but it would certainly be tight. I would certainly have thought that two lanes will be needed between the N3 West and N2 (both directions). It's pretty invariably the case that the turning movements from major intercity routes onto bypasses are the heaviest (hence why it is these movements alone which have been upgraded at Gillooly's, Flying Saucer, and at both ends of the N1 between Pretoria and Joburg).

It's rather unusual that EB Cloete has three lanes in each direction on the mainlines, but only one for all the movements except N2 northbound > N3 westbound which gets two. Getting another lane through at the ground level would be very squeezed by the massive supports that hold up the 3rd and 4th levels (itself rather unusual I think).

[booshank]

Upgrades to the Elands Interchange (N3-N12) too.

This also seems to include direct links between the N12 and N17 so that traffic wanting to go from the one to the other won't have to go via the Rand Airport (N3-N17) interchange:-

You can now see parts of this taking shape: Elands Interchange - Google.

There also seems to be an extra ramp from South Rand Road that isn't in the diagram.

A bit further on along the N12 there is also major work going on at the interchange with the Sybrand van Niekerk Freeway, building a direct connector to replace the northbound R59 to eastbound N12 loop:- N12 exit 402 - Google

[Truvelo]

Where's all the money coming from to upgrade these fantastic junctions?