A417 Missing Link campaign!

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MiChaos
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A417 Missing Link campaign!

Post by MiChaos »

Don't think this is on here yet, apologies if it is.

Gloucestershire County Council are campaigning the Highways Agency for funding for it's solution to the single-carriageway 'gap' in the A419 / A417 link from the M4 to the M5. Instead of tunnels and whatnot, this time it's "the loop"!

http://a417missinglink.co.uk/

To my mind, this looks like a simple, elegant solution to the problem, and takes the biggest danger in the area, the Air Balloon Roundabout, completely out of the picture.

Thoughts? :)
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Truvelo
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Re: A417 Missing Link campaign!

Post by Truvelo »

It looks like a good solution on paper but the curvature of the loop would suggest a sub-NSL speed limit. I would also expect it to be steep so I hope there will be three lanes uphill. Of course, it'll be far superior to what exists there now.
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A303Chris
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Re: A417 Missing Link campaign!

Post by A303Chris »

It is an improvment on whats there now. However movement from the A417 coming from the south on to the A436 then A435 for Cheltenham looks very convuluted. My prefered way of coming off at the Elkstone turning and cutting through the village on to the A435 for Cheltenham or as currently to use the A436 to get back on the A417 missing the queues for the SC section looks like would still be the best option.

However massive improvement but as Truvelo says proballey will not be NSL, given the tight radii proposed
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wrinkly
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Re: A417 Missing Link campaign!

Post by wrinkly »

I think it should be called the "serpent".

A quick estimate the radius of the loop comes out at 375m.
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si404
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Re: A417 Missing Link campaign!

Post by si404 »

I think the 360 degrees turn for traffic bypassing Cheltenham looks like a decent solution :no:
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echowarning
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Re: A417 Missing Link campaign!

Post by echowarning »

Certainly needs doing - the geography around there is a tad nasty though - especially with that hill. From memory there isn't a lot of room to play with coming up the hill from Gloucester.
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Re: A417 Missing Link campaign!

Post by M4 Cardiff »

At 375m radius, a calculated lateral acceleration of 2.6 ms-2 would be generated at 70, which is just over 1/4 g. AT 56, the acceleration would be 1.7ms-2. So if the curve were slightly banked, it would possibly be acceptable for an advisory limit only, however in this day and age I would expect a SPECS 50 from the southern junction dumbbell to the end of the existing DC.

Still, this proposal is a lot better than what's currently there and more feasible than other solutions I have seen discussed. But like most good ideas, it will probably never happen. After all, if we drive, we're planet killers, right??
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Re: A417 Missing Link campaign!

Post by vlad »

si404 wrote:I think the 360 degrees turn for traffic bypassing Cheltenham looks like a decent solution :no:
Traffic heading between the A436 and the northbound M5 may start getting a bit dizzy. At least the loop at the Air Balloon is fairly large - but short of tunnelling under the new A417 I'm not sure what the solution would be.
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wrinkly
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Re: A417 Missing Link campaign!

Post by wrinkly »

Reading off the graph in fig. 5 here, a radius of 375m used with a superelevation of 5% (the maximum desirable) appears to be compatible with a design speed of 85km/h, which presumably means a 50 mph limit.
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Re: A417 Missing Link campaign!

Post by mapboy »

I agree this is far superior to the current situation (well most things would be), though in an ideal world, I'd have liked to have seen the tunnels.
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Re: A417 Missing Link campaign!

Post by Johnathan404 »

How do the traffic levels compare to Hindhead? The D2 link is clearly necessary but I can't help but feel the tunnels would feel over-engineered.
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Re: A417 Missing Link campaign!

Post by Bryn666 »

Better than the current roundabout... get it built.
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Re: A417 Missing Link campaign!

Post by CrackersA361 »

It'll be goodbye to the Air Balloon pub as well as it seems the new carriageways would go right over the existing building judging by their Google Maps drawing!

I like the idea in principle but I use the A436 a fair bit travelling between Bristol and Banbury, so coming up from the M5, onto the A417 and then taking that convoluted route to the A436 seems a bit much. You could have a slip road running on the old A417 alignment up the hill to the new roundabout which has been shifted back. This would at least be helpful for traffic heading northbound. Southbound into Gloucester is tricky though.
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MiChaos
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Re: A417 Missing Link campaign!

Post by MiChaos »

Johnathan404 wrote:How do the traffic levels compare to Hindhead? The D2 link is clearly necessary but I can't help but feel the tunnels would feel over-engineered.
Not sure about the traffic levels but from memory the issue was something to do with the water table, it would be a significant risk and pumps would be needed to have been sited somewhere? I'm not an engineer so I have no idea what I'm on about, and helpfully the details seem to have been wiped from the Highways Agency website!
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Re: A417 Missing Link campaign!

Post by A303Chris »

Johnathan404 wrote:How do the traffic levels compare to Hindhead? The D2 link is clearly necessary but I can't help but feel the tunnels would feel over-engineered.
Very similar according to the DfT AADT web page.

A3 north of Hindhead Tunnels - 33797 AADT
A417 between A436 and A46 - 32549 AADT
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Re: A417 Missing Link campaign!

Post by CrackersA361 »

Considering the location of the road and it's strategic importance as a link between the M4 and M5 for long-distance traffic, as well as more local traffic between Swindon and Cheltenham/Gloucester, I would argue that tunnels could be justified.

That said, the geography in the area is very difficult so it comes as no surprise that there would be difficulties with the water table. It is a very big ridge.
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Re: A417 Missing Link campaign!

Post by t1(M) »

I don't understand that layout - how do you get from Nettleton to Cheltenham or vice versa? There are no south facing slips to/from the A436.
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Re: A417 Missing Link campaign!

Post by wrinkly »

t1(M) wrote:I don't understand that layout - how do you get from Nettleton to Cheltenham or vice versa? There are no south facing slips to/from the A436.
Presumably via the A46. Any other routes invove minor roads.
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Re: A417 Missing Link campaign!

Post by t1(M) »

Even stranger than there being no slip roads from the A417 n/w bound onto the A436 and into Cheltenham, except via Birdlip - there are two slip roads from the A417 south/east bound onto the A436. Why is the second necessary?
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Re: A417 Missing Link campaign!

Post by Truvelo »

As the A417 is far more important in traffic terms than the A436 I'm sure the loss of some of the A436 movements is more than made up by a totally freeflow A417. Providing all movements to and from the A436 would probably add a substantial cost to the scheme.
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