5, 6 and 7 ramp parclos

[jackal]

I don't think we ever had this topic, though there's some relevant discussion in this recent thread: viewtopic.php?t=44352.

Here are some examples:

5 ramp:
A726 East Kilbride: https://www.google.co.uk/maps/@55.75369 ... a=!3m1!1e3
M2 Ballymena: https://www.google.co.uk/maps/@54.87597 ... a=!3m1!1e3
A1(M) Redhouse: https://www.google.co.uk/maps/@53.578879,-1.2124552,15z

6 ramp:
A13 Poplar: https://www.google.co.uk/maps/@51.51143 ... a=!3m1!1e3
A21 Sevenoaks: https://www.google.co.uk/maps/@51.28077 ... a=!3m1!1e3
B8039 Cumbernauld: https://www.google.co.uk/maps/@55.93846 ... a=!3m1!1e3

7 ramp:
A3 Kingston: https://www.google.co.uk/maps/@51.41516 ... a=!3m1!1e3

We can allow variations from classical parclos, like a roundabout or two, provided the general configuration fits the bill.

Must be more?

[Peter Freeman]

By coincidence, I was just about to post in the Diverging Diamonds topic. My post content partly overlaps this Parclo subject, but from a slightly Australian viewpoint. AU examples are included - but I'll keep them out of this UK list!

Parclo's, in their huge variety of configurations, certainly are a fascinating subject.

[KeithW]

Consider this example in Middlesbrough.
https://www.google.com/maps/@54.5629828 ... &entry=ttu

The description used varies, partially unrolled cloverleaf and Whirlpool for example.

[wrinkly]

Old Inns junction, now M80 J6, was originally a 7-ramp parclo on the A80, shown on the 1966 1" map. The missing movement was the sharp left turn onto the northbound A80 but may have been possible via a filling station. Has been discussed in previous threads, including the thread linked in the OP.

[A320Driver]

A36 at A303 (Wylye). 7 ramps, 8 if you count the little service road.

[Truvelo]

A36 at A303 (Wylye). 7 ramps, 8 if you count the little service road.

Had the proposals of 1995 gone ahead then all turning movements could have been freefow.

[Peter Freeman]

Consider this example in Middlesbrough.
https://www.google.com/maps/@54.5629828 ... &entry=ttu

The description used varies, partially unrolled cloverleaf and Whirlpool for example.

Not a parclo. A parclo uses loops to freeflow, or near-freeflow, at least one right turn, but leaves at least one to traverse a signal, a give-way line, or occasionally a roundabout. Your A66 fully-freeflow interchange is half whirlpool, quarter cloverleaf, quarter stack.

(EDIT: Whirlpool = Turbine)

[Peter Freeman]

A36 at A303 (Wylye). 7 ramps, 8 if you count the little service road.

From A303's viewpoint, it's an impure 5-ramp parclo. From A36's viewpoint, it's a trumpet plus a fully-signalised cross. From both roads' combined viewpoint, it provides only one freeflow right turn.
https://www.google.com.au/maps/place/A3 ... ?entry=ttu

[A320Driver]

A36 at A303 (Wylye). 7 ramps, 8 if you count the little service road.

Had the proposals of 1995 gone ahead then all turning movements could have been freefow.

Interested in this, have you got a plan?

Was an improvement part of the Wylye-Stockton Wood scheme? I guess it would have only generated the largest benefit had the wider improvements on the A36 to the north gone ahead. Absolutely no chance of that happening now and to be fair, the junction works well.

[jackal]

A36 at A303 (Wylye). 7 ramps, 8 if you count the little service road.

Had the proposals of 1995 gone ahead then all turning movements could have been freefow.

Interested in this, have you got a plan?

Was an improvement part of the Wylye-Stockton Wood scheme? I guess it would have only generated the largest benefit had the wider improvements on the A36 to the north gone ahead. Absolutely no chance of that happening now and to be fair, the junction works well.

Step this way: viewtopic.php?p=1317219#p1317219

[wallmeerkat]

I don't think we ever had this topic, though there's some relevant discussion in this recent thread: viewtopic.php?t=44352.

Here are some examples:

5 ramp:

A899 Livingston: https://www.google.co.uk/maps/@55.90500 ... a=!3m1!1e3

You'll have to explain this one to me? I see 2 pairs of on/offslips on what was up until the mid 2000s (I used to drive around Livingston a lot during this time as I had a job there) was a clover.

[jackal]

I don't think we ever had this topic, though there's some relevant discussion in this recent thread: viewtopic.php?t=44352.

Here are some examples:

5 ramp:

A899 Livingston: https://www.google.co.uk/maps/@55.90500 ... a=!3m1!1e3

You'll have to explain this one to me? I see 2 pairs of on/offslips on what was up until the mid 2000s (I used to drive around Livingston a lot during this time as I had a job there) was a clover.

You are quite right, it's just a folded dumbbell with four slips. For some reason I had in mind that they'd kept a fifth slip. List in OP edited accordingly.

[wallmeerkat]

I don't think we ever had this topic, though there's some relevant discussion in this recent thread: viewtopic.php?t=44352.

Here are some examples:

5 ramp:

A899 Livingston: https://www.google.co.uk/maps/@55.90500 ... a=!3m1!1e3

You'll have to explain this one to me? I see 2 pairs of on/offslips on what was up until the mid 2000s (I used to drive around Livingston a lot during this time as I had a job there) was a clover.

You are quite right, it's just a folded dumbbell with four slips. For some reason I had in mind that they'd kept a fifth slip. List in OP edited accordingly.

No worries thanks I was wondering if we were counting the roundabout sliproad or so. Looking up Google Earth the imagery from 2004 shows it under construction. As much as they're unique (one still exists to the south) I disliked that the looping clover onslips ended at a give way, and you had more or less a standing start to get onto the A899

[AndyB]

I would debate M2 (NI) J11’s presence in that list. Functionally, it’s a diamond with massive splays because of the Braid river and an extra loop added from a parclo.

If it had had the second loop you’d expect in a parclo (for example, the northbound offslip), then it would have been the other way round.

[jackal]

I would debate M2 (NI) J11’s presence in that list. Functionally, it’s a diamond with massive splays because of the Braid river and an extra loop added from a parclo.

If it had had the second loop you’d expect in a parclo (for example, the northbound offslip), then it would have been the other way round.

Surely "diamond with an extra loop" is a description of a typical 5 ramp parclo configuration? It certainly is functionally different from a diamond given one of the right turns can be made via the loop rather than turning across opposing traffic.

[Peter Freeman]

I would debate M2 (NI) J11’s presence in that list. Functionally, it’s a diamond with massive splays because of the Braid river and an extra loop added from a parclo.

https://www.google.com.au/maps/place/Ba ... ?entry=ttu

As Jackal said, it is a parclo. In fact, it's almost a text-book 5-ramp layout, but not quite -

a) The ramp in the SE quadrant has an unusually wide splay, presumably to avoid the river, as you said.
b) None of the at-grade intersections are signalised, presumably because, trafficwise, they don't need it.
c) The ramp in the SW quadrant has an unusually wide splay, presumably because, in this un-signalised situation, it was thought better to not co-locate two right-turn give-ways.
d) The right turn that uses the loop gets a true freeflow (yippee!). This is unusual in a five-ramp, because two other right turns need to be passed by before reaching the diverge into the loop, and in a signalised situation these would cancel the freeflow. You can therefore sail freely through here, as long as no-one waiting at a give-way line runs into your side.

So, not a classic layout, but parclo's are so diverse, and so site-customiseable, that few are classic! I assume this interchange works well enough. You could say that including the loop has allowed the at-grade intersections to remain as give-ways, and so: a fair trade.The non-motorway road appears to be fairly minor, and I see no evidence of significant congestion. Nice job.

[jackal]

^ I wouldn't really call it freeflow given the movement has to go through two priority junctions within the interchange. But otherwise I agree.

[Keiji]

Consider this example in Middlesbrough.
https://www.google.com/maps/@54.5629828 ... &entry=ttu

The description used varies, partially unrolled cloverleaf and Whirlpool for example.

Not a Parclo. A parclo uses loops to freeflow, or near-freeflow, at least one right turn, but leaves at least one to traverse a signal or a give-way line. Your A66 fully-freeflow interchange is half whirlpool, quarter cloverleaf, quarter stack.

Well, I've always used the term "Parclo" to refer to this type of junction, which is fully freeflow: Partially Unrolled Cloverleaf

In fact, it was only later that I started hearing people call junctions that weren't freeflow "Parclo"s, and that's always sounded odd to me.

[jackal]

Consider this example in Middlesbrough.
https://www.google.com/maps/@54.5629828 ... &entry=ttu

The description used varies, partially unrolled cloverleaf and Whirlpool for example.

Not a Parclo. A parclo uses loops to freeflow, or near-freeflow, at least one right turn, but leaves at least one to traverse a signal or a give-way line. Your A66 fully-freeflow interchange is half whirlpool, quarter cloverleaf, quarter stack.

Well, I've always used the term "Parclo" to refer to this type of junction, which is fully freeflow: Partially Unrolled Cloverleaf

In fact, it was only later that I started hearing people call junctions that weren't freeflow "Parclo"s, and that's always sounded odd to me.

Parclo is the global term for a partial cloverleaf: https://en.m.wikipedia.org/wiki/Partial ... nterchange

Some time after this use of parclo was established, Sabristi starting using the term "partially-unrolled cloverleaf" for a freeflow interchange design that is used at three sites in the UK. I believe this began with, or was at least popularised by, Chris's CBRD website, the ancestor of the site you linked. Using international terminology one would call the design a cloverstack variant (it has one stack-like connector and one turbine like connector running parallel with each other whereas a classic cloverstack uses two stack-like connectors, e.g., https://www.google.co.uk/maps/@48.9732494,2.4883389,16z).

Over time some SABRE users heard the word parclo used in the international sense, misunderstood it as a contraction of partially-unrolled cloverleaf, and started using it with this new meaning. But certainly now, where we have better familiarity with international terminology, parclo is generally understood on SABRE as referring to a partial cloverleaf rather than a partially-unrolled cloverleaf.

[Peter Freeman]

Using international terminology one would call the design a cloverstack variant (it has one stack-like connector and one turbine like connector running parallel with each other whereas a classic cloverstack uses two stack-like connectors, e.g., https://www.google.co.uk/maps/@51.12081 ... 369921,12z).

Jackal, did you insert the wrong URL here ?