M20 New Junction 10A Ashford

[A303Chris]

This just popped in my inbox this afternoon and it is a Highways England consultation on a new junction 10a approximately 1/2 mile to the east of the existing junction 10 on the M20 to improve capacity. As a result of the proposals the existing junction 10 would lose its east facing slip roads.

M20 Junction 10A Consultation

[Berk]

Bit surprised I didn't see this earlier, given that I was looking at the site...

[booshank]

Shouldn't this be Ashford?

[A303Chris]

Shouldn't this be Ashford?

Yes it should and title amended. I have been looking at site in near Maidstone at work this afternoon and it got stuck in my head

[Peter Freeman]

Yet another NEW-BUILD signalised 2-bridge roundabout

[nowster]

Yet another NEW-BUILD signalised 2-bridge roundabout

If it's signalized it's a tacit admission that it's of inadequate capacity right from the start. Why not build a SPUI (or its cousin the diverging diamond) instead? It would have higher capacity and cost about the same.

[Berk]

And if it's signalised, it'll have a 40 mph limit!!

[Fluid Dynamics]

For me the problem is the omission of the eastbound on slip at junction 10. This means any traffic from the northern section of the A2070 has to take a very circuitous route to get on the M20 coast bound and much of the traffic travelling coast bound on the M20 will exit at junction 10 rather than doubling back at 10a surely. In my opinion a new free flow J10a with coast bound slips would be preferable and keep the existing junction 10 as it is.

[c2R]

For me the problem is the omission of the eastbound on slip at junction 10. This means any traffic from the northern section of the A2070 has to take a very circuitous route to get on the M20 coast bound and much of the traffic travelling coast bound on the M20 will exit at junction 10 rather than doubling back at 10a surely. In my opinion a new free flow J10a with coast bound slips would be preferable and keep the existing junction 10 as it is.

There's only 700m between the two junctions, so weaving would occur if these were built retaining the existing eastbound sliproads at J10. They would need to add c/d lanes which I suppose would be too expensive.

[booshank]

Yet another NEW-BUILD signalised 2-bridge roundabout

Might be a silly question, but do they even do some sort of cost-benefit analysis to come up with something like this, or is it decided in advance that a two level signalised roundabout is all that is politically/financially acceptable and it just has to do no matter how inadequate?

[Chris5156]

This proposal is back from the dead, and I can't say I'm too pleased to see it back in its current form. There's an older thread on it here.

[RichardA35]

..Might be a silly question, but do they even do some sort of cost-benefit analysis to come up with something like this, or is it decided in advance that a two level signalised roundabout is all that is politically/financially acceptable and it just has to do no matter how inadequate?

There will have been a clean sheet of paper at the beginning of the study with no options off the table. Each of these is appraised and the best performing are taken forward for more detailed appraisal.
From having lived in the area for a year or two, there are the constraints of the urban fringe all around the junction precludng some of the more exotic alternatives. For example the obvious development site to the south (land with planning permission = very expensive) and the new roundabout is also on the site of a garden centre (established business premises = v expensive).

[Fluid Dynamics]

For me the problem is the omission of the eastbound on slip at junction 10. This means any traffic from the northern section of the A2070 has to take a very circuitous route to get on the M20 coast bound and much of the traffic travelling coast bound on the M20 will exit at junction 10 rather than doubling back at 10a surely. In my opinion a new free flow J10a with coast bound slips would be preferable and keep the existing junction 10 as it is.

There's only 700m between the two junctions, so weaving would occur if these were built retaining the existing eastbound sliproads at J10. They would need to add c/d lanes which I suppose would be too expensive.

What I was suggesting was reinstating the coast bound on-slip at J10 and getting rid of the coastbound off-slip at J10a. This would avoid weaving. I can't see why traffic at 10a would want to double back to access Ashford or the new developments. I wouldn't change the London bound proposals.

[Jam35]

Looks seriously stupid clogging up the enormous roundabout with westbound traffic on the A20. Should really split it out into two junctions.

[A303Paul]

I really can't see what on earth the point is of this.

All it appears to do is duplicate the junction and add an extra roundabout to the A2070, plus it sticks the A20 through both junctions and cuts off access to the minor road to Mersham.

Woudln't it be better to put a grade separated dumbell interchange from the A2070 into the new Development

Or is it the beginning of a plan for an A2070 Ashford Northern Bypass?

[c2R]

I really can't see what on earth the point is of this.

All it appears to do is duplicate the junction and add an extra roundabout to the A2070, plus it sticks the A20 through both junctions and cuts off access to the minor road to Mersham.

Woudln't it be better to put a grade separated dumbell interchange from the A2070 into the new Development

Or is it the beginning of a plan for an A2070 Ashford Northern Bypass?

If you look at the highways england document you will see a large area to the south of the new A2070 link road, with a comment that there is a proposed access about half way along. Lovely lovely development land there, bringing more traffic into the mess of junctions and roundabouts that will be created. It's all pretty horrible really.

[Vierwielen]

This just popped in my inbox this afternoon and it is a Highways England consultation on a new junction 10a approximately 1/2 mile to the east of the existing junction 10 on the M20 to improve capacity. As a result of the proposals the existing junction 10 would lose its east facing slip roads.

M20 Junction 10A Consultation

This will make is a little easier for those who wish to use the Tesco Restaurant (marked "Superstore" on the consultation plan) rather than the Eurtotunnel terminus restaurant.

[A21Will]

The old phrase "two wrongs don't make a right" springs to mind here. I'm enjoying the arrival of a roundabout where all three exits are called the A2070. I am also surprised that this isn't (yet) being used as an excuse to close the very horrid London bound on slip at J10.

[Brenley Corner]

I may be in a minority here, but I'm not sure I can see what the problems are here. The junction is being built solely to support the massive developments that have been given approval to the south of the junction. Without these developments the new junction would not be occurring and without the junction the developments would not be occurring. These developments will generate a lot of commuter and freight traffic needing access to the M20 and the exiting J10 simply cannot cope with any more traffic; there is no problem with the amount of traffic generated from the A2070 (reclassified B road) coming from the North.

Tony

[Peter Freeman]

I may be in a minority here, but I'm not sure I can see what the problems are ...

I don't think this proposal is a disaster, but -

1. Two-bridge roundabout for 10a: no, use a signalised diamond or diverging diamond, most effectively solving the throughput problem.

2. Brand new roundabout signalised: please no.

3. Keep J10's eastern ramps, but merge them into 10a's western ramps instead of into the mainline. Coast-bound traffic entering at J10 would immediately have to pass through J10a, but it needs to do that anyway in the proposed design, after it has faced further signals at J10 and travelled further distance and negotiated the new southern roundabout. London-bound traffic wanting J10 would exit to J10a, and then have a choice of route: down the ramp and up again, or use the southern way. Appropriate signing would pragmatically get the balance right. (Caution: passing ACROSS J10a would not be possible with a diverging diamond).

As a more general comment, I have often thought that adding junctions would solve some problems on UK motorways. For a densely-populated island the average junction spacing has always seemed rather wide to me. To simply convert a nearby crossing road into a junction by adding ramps (no new structure) would often be possible, and would offer cost-effective relief to a struggling nearby intersection that is difficult to upgrade. This M20 proposal is almost my wish, except that the structures are new.