M6 Junction 19 'improvements'

The study of British and Irish roads - their construction, numbering, history, mapping, past and future official roads proposals and general roads musings.

There is a separate forum for Street Furniture (traffic lights, street lights, road signs etc).

Registered users get access to other forums including discussions about other forms of transport, driving, fantasy roads and wishlists, and roads quizzes.

Moderator: Site Management Team

Post Reply
Jeni
Banned
Posts: 7313
Joined: Sun Nov 28, 2004 22:28

Re: M6 Junction 19 'improvements'

Post by Jeni »

roverman wrote:The thing I don't get is how building the new A556 road actually made this roundabout worse. There is a free flow lane onto M6 (S) which sacrificed good access to the old A556 (B5569) and lets be honest a lot of the traffic on the A556 is aiming for the M6 (S) so why is it now harder to travel through it?
Sorry, that doesn't make sense. Worse in what way?
Benny
Member
Posts: 2240
Joined: Sat Dec 28, 2013 18:04

Re: M6 Junction 19 'improvements'

Post by Benny »

I often use the A556 to get to the M6 at J19 to travel home after visiting friends in Manchester. Since the new road was opened I have found its actually taking longer to actually get onto the M6 with traffic building up along the free flow lane for around the last 1/2 mile or so.

Is this because of the roadworks (which were in force before the new road opened anyway) or the new road generating higher volumes of traffic into the roundabout junction?
Living my life on the edge......of two counties!

Formerly known as Roverman

Still driving a British built car, made in a former Rover factory......
avtur
Member
Posts: 4902
Joined: Wed Oct 28, 2009 16:51
Location: Haywards Heath

Re: M6 Junction 19 'improvements'

Post by avtur »

roverman wrote:........The thing I don't get is how building the new A556 road actually made this roundabout worse. There is a free flow lane onto M6 (S) which sacrificed good access to the old A556 (B5569) and lets be honest a lot of the traffic on the A556 is aiming for the M6 (S) so why is it now harder to travel through it?......
I think the geometry of the through lane in the new scheme is more restrictive than what is was previously, the left turn on the through lane as it reaches the roundabout appears sharper than the original routing. The first time I drove south on the new road I was disappointed that there was only one lane through onto the M6S as well as the tightness of the turn. The new layout is certainly more of an impediment to free movement of larger vehicles than the original layout. I'm generally quite happy with other aspects of the new road, although the one feature I would like to have seen is a through route from M6N onto A556N.

I presume that the proposed two new bridges will run at the same level as the roundabout with traffic lights controlling their intersection?
User avatar
mapboy
Member
Posts: 1111
Joined: Sat Oct 29, 2011 08:53
Location: Birmingham

Re: M6 Junction 19 'improvements'

Post by mapboy »

avtur wrote:I presume that the proposed two new bridges will run at the same level as the roundabout with traffic lights controlling their intersection?
That is my understanding - like a 'Hamburger' junction but with the flow directions of the central carriageways reversed with respect to if it was simply a dual-carriageway bisecting the roundabout.
fras
Member
Posts: 3590
Joined: Tue Apr 10, 2012 18:34

Re: M6 Junction 19 'improvements'

Post by fras »

Is this because of the roadworks (which were in force before the new road opened anyway) or the new road generating higher volumes of traffic into the roundabout junction?
It's neither. Now with the new road, the traffic flows very freely off the M56 onto the new A556 link and all the way down it. There are no longer two sets of traffic light junctions to be negotiated as there were on the old road, so it all piles up at the south end, (or Jn 19 !!). What you have found proves what I said would happen; southbound traffic will all pile up at the south end of the new link, (at busy/peak times, of course, as I have so far not had any difficulty at all getting from the new A556 Link southbound onto the A556 to go towards Winsford.
User avatar
wrinkly
Member
Posts: 8989
Joined: Tue Mar 04, 2008 12:17
Location: Leeds

Re: M6 Junction 19 'improvements'

Post by wrinkly »

The BBC has a render of the proposed hamburger.

It seems to show the existing bridges with a greater span than they actually have.

http://www.bbc.co.uk/news/uk-england-ma ... r-43866570
User avatar
jackal
Member
Posts: 7549
Joined: Tue Jan 08, 2008 23:33
Location: M6

Re: M6 Junction 19 'improvements'

Post by jackal »

The information events are at Mere and Tabley Community Club, Chester Road, Mere, between 2pm and 8pm on Thursday, May 3, and from 10am and 6pm on Wednesday, May 16. http://www.knutsfordguardian.co.uk/news ... w_at_Mere/

Looking at the render, I wonder if there is scope for an A556 flyover, creating a freeflow limited access junction similar to Catthorpe.

Image
Also it looks like the southbound freeflow may be retained, contrary to earlier plans.
Last edited by jackal on Tue Apr 24, 2018 12:32, edited 2 times in total.
User avatar
Truvelo
Member
Posts: 17468
Joined: Wed May 29, 2002 21:10
Location: Staffordshire
Contact:

Re: M6 Junction 19 'improvements'

Post by Truvelo »

I don't think a flyover linking both sides of the A556 would be the most useful in terms of traffic flow. If the current proposals for the two right turns were grade separated similar to this drawing it would make far more sense.

Image
How would you like your grade separations, Sir?
Big and complex.
User avatar
jackal
Member
Posts: 7549
Joined: Tue Jan 08, 2008 23:33
Location: M6

Re: M6 Junction 19 'improvements'

Post by jackal »

The flyover would mean the A556 mainline AND the two main turns get freeflowed. All the stuff that isn't in red gets closed:
M6 A556 freeflow - Copy.png
fras
Member
Posts: 3590
Joined: Tue Apr 10, 2012 18:34

Re: M6 Junction 19 'improvements'

Post by fras »

To be honest the new junction is not really all that bad, although it can jam up a bit for M6 South in peak periods. Those like me doing A556-roundabout-A556 towards Winsford seem to have few problems. I pass this way every month on a Wednesday for the Midget and Sprite Club meeting at the Kilton on the A50. Incidentally work still continues in the fields north of the A50 overbridge to landscape it all. There only seems to be one man and his digger working ! I think the works compound by the A56 roundabout at Castle Hill is still there. It's amazing how long the contractors remain working after the main construction finishes.
A320Driver
Member
Posts: 448
Joined: Fri Jun 24, 2005 19:11
Location: Leatherhead

Re: M6 Junction 19 'improvements'

Post by A320Driver »

fras wrote:To be honest the new junction is not really all that bad,
Which makes it all the more staggering that a vast amount of money is being spent here for an improvement that perhaps isn’t as justified as others on the network.
Two new bridges to span the M6, yet we still will have no freeflow, and will result in traffic approaching Manchester from southern England, having to negotiate what is effectively two signalised crossroads. :roll:
Formerly ‘guvvaA303’
User avatar
Bryn666
Elected Committee Member
Posts: 35755
Joined: Thu Jun 20, 2002 20:54
Contact:

Re: M6 Junction 19 'improvements'

Post by Bryn666 »

I maintain that I have never been held up by J19 - it was always the old A556 itself that was the problem.

This improvement is more about managing the future flows that a J19 lane drop when the smart motorway works finish will bring.
Bryn
Terminally cynical, unimpressed, and nearly Middle Age already.
She said life was like a motorway; dull, grey, and long.

Blog - https://showmeasign.online/
X - https://twitter.com/ShowMeASignBryn
YouTube - https://www.youtube.com/@BrynBuck
dcrc2
Member
Posts: 111
Joined: Tue Mar 25, 2014 23:22
Location: Stevenage

Re: M6 Junction 19 'improvements'

Post by dcrc2 »

I like the HE plan because, whether intentionally or not, there does seem to be plenty of scope to upgrade it further in future. It looks like the bridge being built is compatible with jackal's plan from p3 of this thread which would give free-flow for the northbound M6->A556 relatively cheaply. Or as an alternative next step, they could open up an access from the A5033 to the M6(S) through Knutsford services, and close off the corresponding movement at J19, which might allow one set of lights on the north side of J19 to be removed.
User avatar
jackal
Member
Posts: 7549
Joined: Tue Jan 08, 2008 23:33
Location: M6

Re: M6 Junction 19 'improvements'

Post by jackal »

"On 21 February 2019, the Department for Transport (DfT) published an Order under section 10 of the Highway Act 1980." Construction is to start by Spring 2020.

https://highwaysengland.co.uk/projects/m6-junction-19/
fras
Member
Posts: 3590
Joined: Tue Apr 10, 2012 18:34

Re: M6 Junction 19 'improvements'

Post by fras »

jackal wrote: Fri Mar 01, 2019 19:49 "On 21 February 2019, the Department for Transport (DfT) published an Order under section 10 of the Highway Act 1980." Construction is to start by Spring 2020.

https://highwaysengland.co.uk/projects/m6-junction-19/
I can't see how this scheme can offer any improvement at all. At the moment, if I come off the M6 going north, to go north on the new A556 road, I have two sets of traffic lights to pass. With this scheme it is still two sets, so no improvement.

However, for the poor old motorist coming up the A556 from the Chester direction intending to carry on to Manchester on the A556, the number of sets of traffic lights doubles from two to four, and from one to three in the opposite direction. The whole proposal looks completely barmy !
ais523
Member
Posts: 1139
Joined: Tue Sep 08, 2015 19:52
Location: Birmingham

Re: M6 Junction 19 'improvements'

Post by ais523 »

How often do you have to stop at both sets of lights?

With this particular junction design, it should be possible to time them so that the second set of lights never blocks M6(N)→A556(N) traffic.

Also, with traffic light junctions (in fact, most types of flat junction), giving more time to one movement means giving less time to another movement, and vice versa. You've noted that some minor movements are becoming slower. This is because the major movements are becoming faster.

The key improvement of the junction, though, is the reduction in conflicts. The number of conflict points, and the number of conflicting streams of traffic, are the main determiner in how freely you can keep traffic flowing at the junction (so-called "free-flow junctions" have that name due to having zero conflict points, but the general principle applies even to junctions where conflict points do exist). With the new junction, very few movements conflict (it's the A556 straight ons and right turns that are getting the raw end of the deai, but with what's almost a flat junction, some of them have to). The big advantage of major movements that don't conflict is that they can all be given green time at the lights simultaneously (sequenced so that traffic on a major movement only ever needs to stop at one set of lights, and often has green all the way), which basically doubles or triples the capacity over a junction design where one major movement has to be stopped to make room for another.

Compare the existing junction, where only one movement (other than M6 straight on, which is grade-separated, and left turns, which never conflict with anything) can be treated as major. Presumably that's the M6 northbound to A556 northbound right turn, but it can't be given that large a proportion of the green time because it conflicts with every other right turn and the A556 straight on, and those movements aren't sufficiently unimportant that they can be starved altogether. The new design makes it possible to give the major movement a much higher proportion of green time without having to starve the less important movements as a consequence. (That's the reason for the cut-through from the M6 southbound, despite it not being a major problem; it removes another conflicting movement from the main part of the junction, which can safely be set to green at the same time as the cut-through from the M6 northbound is, and thus doesn't use up any green time from the other minor movements. That means that you can increase the green time for the main movement quite a lot and still have enough time to keep the minor movements flowing.)

I guess a better way to think about the junction is in terms of the total waiting time, not the number of lights you have to go through. The total waiting time will be based mostly on the proportion of time the route you want to take has a) a green light, and b) no obstructions before that green light that would prevent you going through it (if there is such an obstruction, e.g. a red light earlier in the junction, you have to wait for that one to clear first). The new design can synchronize timings, meaning that b) is not a problem for major movements (you'd even have some scope to help out with the timing of minor movements, too). The new design has many fewer conflicts, meaning that a) can be improved for every movement, both the major and minor ones, as there's more scope for usefully sharing green time. So I'd expect the new junction to flow much more freely than the old one, if timed well.
Micro The Maniac
Member
Posts: 1175
Joined: Thu Jun 25, 2015 13:14
Location: Gone

Re: M6 Junction 19 'improvements'

Post by Micro The Maniac »

ais523 wrote: Sat Mar 02, 2019 03:17 How often do you have to stop at both sets of lights?
Never under-estimate a transport agency's ability to completely b****r up traffic light synchronisation
ais523
Member
Posts: 1139
Joined: Tue Sep 08, 2015 19:52
Location: Birmingham

Re: M6 Junction 19 'improvements'

Post by ais523 »

Micro The Maniac wrote: Sat Mar 02, 2019 07:09
ais523 wrote: Sat Mar 02, 2019 03:17 How often do you have to stop at both sets of lights?
Never under-estimate a transport agency's ability to completely b****r up traffic light synchronisation
I was very careful to make the statements in my post conditional on the lights actually being timed correctly :-D
User avatar
Big L
Deputy Site Manager
Posts: 7517
Joined: Sun Nov 14, 2010 20:36
Location: B5012

Re: M6 Junction 19 'improvements'

Post by Big L »

fras wrote: Sat Mar 02, 2019 00:12 I can't see how this scheme can offer any improvement at all. At the moment, if I come off the M6 going north, to go north on the new A556 road, I have two sets of traffic lights to pass. With this scheme it is still two sets, so no improvement...
Which set of lights are you forgetting? One at the top of the off slip, one where the A556 from the West joins the roundabout, one where the M6 southbound off slip joins the roundabout. That's three.

Edit. Sometimes I get stopped by all 3 sets of lights, sometimes none at all.
Make poetry history.

Did you know there's more to SABRE than just the Forums?
Help with maps using the new online calibrator.
Add your roads knowledge to the SABRE Wiki.
noordinarymorning
Member
Posts: 201
Joined: Wed Dec 05, 2007 12:56
Location: Nottingham (ex-Bristol)

Re: M6 Junction 19 'improvements'

Post by noordinarymorning »

ais523 wrote: Sat Mar 02, 2019 03:17 How often do you have to stop at both sets of lights?

[SNIP]

So I'd expect the new junction to flow much more freely than the old one, if timed well.
Thanks for the detailed explanation ais523, it makes for very interesting reading!

It's good to understand why sometimes counter-intuitive layouts can help in a way which isn't immediately obvious.
Post Reply