M11 Junc 8

[millionmiledriver]

I use this almost every day and there have been roadworks since the start of the year .Apart from coning off lanes and the odd hole on the verge and bits of equipment parked I really cannot see what they are doing .They say its a junction improvement but it seems even more chaos for nothing .Can anyone shed light on this ?

[jackal]

https://www.essexhighways.org/highway-s ... ent-scheme

[millionmiledriver]

Thank you Jackal makes a lot more sense now ! Hindsight is a wonderful thing but building a service area here was not the best place quite often queues going into it block the roundabout like so many service areas its not brilliantly designed

[jackal]

You're welcome!

They should really provide freeflow for M11 north to/from A120 east. The services would not be such a problem if traffic going between the airport and Cambridge didn't have to use that part of the roundabout.

[Bryn666]

You're welcome!

They should really provide freeflow for M11 north to/from A120 east. The services would not be such a problem if traffic going between the airport and Cambridge didn't have to use that part of the roundabout.

This won't please the NH "where will we slot in the Amazon depot" mentality but here you go. The local slips are optional given all the other ancillary airport stuff around that point.

[A303Chris]

I never understand replacing roundabouts with traffic signals as is the case with the A120 / A1250 junction, as they always seem to make congestion worse.

[Bryn666]

I never understand replacing roundabouts with traffic signals as is the case with the A120 / A1250 junction, as they always seem to make congestion worse.

The aim is to provide for future development which requires active travel provision as evidenced by the toucans across the middle. The alternative was to provide signalised entries on the roundabout for these crossings presumably, which takes us into the hamburger thread and why it's better to replace roundabouts with proper signal junctions instead of crash prone signalised roundabout hybrids.

[millionmiledriver]

Wren kitchens have applied having been turned down for a distribution depot on that self same roundabout .They have been turned down already it is anticipated 600 extra truck movements a day should they get this !

[c2R]

I'm sure the vast numbers of new houses in and around the junction are also helping.... but yes, the act of building a motorway service area at the same junction they'd just given permission for a massive international airport to be built at defies logic

[KeithW]

I'm sure the vast numbers of new houses in and around the junction are also helping.... but yes, the act of building a motorway service area at the same junction they'd just given permission for a massive international airport to be built at defies logic

Birchanger Green services opened in 1995 so its a bit late to worry about than now As I recall before it opened the only option was the Esso Garage on what was then the A120 now B1256. Given that its the only services on the M11 its was rather welcomed at the time.

[Peter Freeman]

Another motorway junction that began, presumably, pre-airport expansion, as just-about OK; grew, in stages, each one in penny-pinching mode, to be silly; and now its capacity is being half-heartedly increased again by laying a few small strips of asphalt and eliminating one roundabout. If this isn't in Chris's 'Bad Junctions' list, it certainly should be. And even more so if Bryn's red extra slips got added in.

Rip it all up except for the bridges and M11 mainline, and start over, with a rational design. There's lots of space.

[Bryn666]

Another motorway junction that began, presumably, pre-airport expansion, as just-about OK; grew, in stages, each one in penny-pinching mode, to be silly; and now its capacity is being half-heartedly increased again by laying a few small strips of asphalt and eliminating one roundabout. If this isn't in Chris's 'Bad Junctions' list, it certainly should be. And even more so if Bryn's red extra slips got added in.

Rip it all up except for the bridges and M11 mainline, and start over, with a rational design. There's lots of space.

What, making the M11-A120 movements a full directional-T is now a bad junction???

My suggestion does exactly what any good junction design does - splits out the local movements from the strategic ones.

[Peter Freeman]

Another motorway junction that began, presumably, pre-airport expansion, as just-about OK; grew, in stages, each one in penny-pinching mode, to be silly; and now its capacity is being half-heartedly increased again by laying a few small strips of asphalt and eliminating one roundabout. If this isn't in Chris's 'Bad Junctions' list, it certainly should be. And even more so if Bryn's red extra slips got added in.

Rip it all up except for the bridges and M11 mainline, and start over, with a rational design. There's lots of space.

What, making the M11-A120 movements a full directional-T is now a bad junction???

I didn't mean to simply dismiss your suggestion Bryn. A full directional-T between A120 and M11 would be a good basis as the core of this complex meeting of roads. But if you look at the totality of your sketch, it's all the other pre-existing bits-n-pieces that consign it to the B.J. List.

These joke-junctions arise by a series of 'accidents' - thought-bubble add-ons that fail to have an end-game vision. This might sound like, and is, 'the wisdom of hindsight', but more vision really is required. The same incremental process produced other tragedies: M1 J23/24, M1 J13, Switch Island, etc.

Your final design provides three different ways that (for example) Round Coppice Road traffic could reach M11 north. In fact, there are multiple paths that many of the minor and major movements could take (some passing through up to 3 roundabouts). Even with a commendable directional-T at its core, you wouldn't actually design an overall mess like this. Also, any junction that includes one of these weird roundabouts with an extra loop sticking out of its end (here and, for example, M40 J4) is preposterous.

I know it's a dilemma - we haven't invented reliable crystal balls yet. I suppose the designer of M11's original J8 would have been surprised to hear that one day his junction would serve Britain's 3rd international airport. But all serious motorway plans should have future contingencies in mind, and in their designs.

My suggestion does exactly what any good junction design does - splits out the local movements from the strategic ones.

A subsidiary point, but I take issue with this ^ statement, especially the word 'any'. My draft: "What every good junction design does is provide adequate, safe and efficient flow paths for all required movements, both local and strategic". 'Splitting the local movements out', if that's what happens, should be a by-product, not an objective. Put another way, it will sometimes be the means to the end, but not actually the end itself.

[skiddaw05]

Birchanger Green services opened in 1995 so its a bit late to worry about than now As I recall before it opened the only option was the Esso Garage on what was then the A120 now B1256. Given that its the only services on the M11 its was rather welcomed at the time.

I still remember when there were 'No services on motorway' signs as you joined the M11

[Bryn666]

Another motorway junction that began, presumably, pre-airport expansion, as just-about OK; grew, in stages, each one in penny-pinching mode, to be silly; and now its capacity is being half-heartedly increased again by laying a few small strips of asphalt and eliminating one roundabout. If this isn't in Chris's 'Bad Junctions' list, it certainly should be. And even more so if Bryn's red extra slips got added in.

Rip it all up except for the bridges and M11 mainline, and start over, with a rational design. There's lots of space.

What, making the M11-A120 movements a full directional-T is now a bad junction???

I didn't mean to simply dismiss your suggestion Bryn. A full directional-T between A120 and M11 would be a good basis as the core of this complex meeting of roads. But if you look at the totality of your sketch, it's all the other pre-existing bits-n-pieces that consign it to the B.J. List.

These joke-junctions arise by a series of 'accidents' - thought-bubble add-ons that fail to have an end-game vision. This might sound like, and is, 'the wisdom of hindsight', but more vision really is required. The same incremental process produced other tragedies: M1 J23/24, M1 J13, Switch Island, etc.

Your final design provides three different ways that (for example) Round Coppice Road traffic could reach M11 north. In fact, there are multiple paths that many of the minor and major movements could take (some passing through up to 3 roundabouts). Even with a commendable directional-T at its core, you wouldn't actually design an overall mess like this. Also, any junction that includes one of these weird roundabouts with an extra loop sticking out of its end (here and, for example, M40 J4) is preposterous.

I know it's a dilemma - we haven't invented reliable crystal balls yet. I suppose the designer of M11's original J8 would have been surprised to hear that one day his junction would serve Britain's 3rd international airport. But all serious motorway plans should have future contingencies in mind, and in their designs.

My suggestion does exactly what any good junction design does - splits out the local movements from the strategic ones.

A subsidiary point, but I take issue with this statement. Especially the word 'any'. My draft: "What every good junction design does is provide adequate, safe and efficient flow paths for all required movements, both local and strategic". 'Splitting the local movements out', if that's what happens, should be a by-product, not an objective.

There would only be two ways that traffic from Round Coppice Road could reach the M11 north - either via the existing J8 or the direct slips shown running north of the directional-T. There simply isn't the space to put movements into the directional-T without considerable structural content and masses of expense that could be achieved without that effort.

If you go back in time on Google Earth you can see that in 1999 M11 J8 was already laid out for the direct slips - the old airport approach road was absorbed into the A120 expressway as part of it. The expectation was always local traffic would have to muddle through the roundabouts.

[Peter Freeman]

^ Sorry - yes, only two ways. But, with respect, the resultant layout is nevertheless a mess. If your two connectors that form the directional-T were added, then the remainder could surely be 'cleaned up'. And it could (not necessarliy should) be done without any roundabouts. I won't try to design it, since you or Jackal or Truvelo could do a better job; and the design would be a waste of time because, with the major movements taken care of, justification of extra cost would be impossible.

A final remark: the current plan will be implemented, and it will help, as these incremental 'tinkers' always do. I have just one wish for a change to the current plan: the western roundabout replacement could be a straight-across signalised crossroads, rather than the staggered version. More efficient, fewer stops.

[Bryn666]

^ Sorry - yes, only two ways. But, with respect, the resultant layout is nevertheless a mess. If your two connectors that form the directional-T were added, then the remainder could surely be 'cleaned up'. And it could (not necessarliy should) be done without any roundabouts. I won't try to design it, since you or Jackal or Truvelo could do a better job; and the design would be a waste of time because, with the major movements taken care of, justification of extra cost would be impossible.

A final remark: the current plan will be implemented, and it will help, as these incremental 'tinkers' always do. I have just one wish for a change to the current plan: the western roundabout replacement could be a straight-across signalised crossroads, rather than the staggered version. More efficient, fewer stops.

I agree - I was just throwing a quick and dirty plan out. I'd quite like to look at it in more detail and see how it could be rationalised.

Also agree about the crossroads - a stagger is just adding in delay but I suspect that NMU route has dictated the design somewhat as well as existing land take and avoiding expensive land purchase which for highways is apparently verboten but perfectly OK for an Amazon shed.

[Peter Freeman]

Also agree about the crossroads - a stagger is just adding in delay but I suspect that NMU route has dictated the design somewhat as well as existing land take and avoiding expensive land purchase which for highways is apparently verboten but perfectly OK for an Amazon shed.

No land purchase required: it would definitely fit in the space released by the roundabout. The northern arm only, which is very minor and not wide, simply needs moving westwards to oppose the southern arm.

NMU route - yes, to equate to the current proposal, two crossings instead of one would need to be negotiated. Not really an onerous requirement.

I would also introduce a little more lane flare (and design flair!) at the stop lines.

[Bryn666]

Also agree about the crossroads - a stagger is just adding in delay but I suspect that NMU route has dictated the design somewhat as well as existing land take and avoiding expensive land purchase which for highways is apparently verboten but perfectly OK for an Amazon shed.

No land purchase required: it would definitely fit in the space released by the roundabout. The northern arm only, which is very minor and not wide, simply needs moving westwards to oppose the southern arm.

NMU route - yes, to equate to the current proposal, two crossings instead of one would need to be negotiated. Not really an onerous requirement.

I would also introduce a little more lane flare (and design flair!) at the stop lines.

https://goo.gl/maps/PatzAkv3rQNEX2Pt6 I just randomly picked a junction from Sydney here and was impressed to see there was a single stage pedestrian movement. Presumably it only runs when the button is pressed but this would be contorted into a horrible staggered arrangement here which would deter pedestrian use due to the lack of direct routes.

It also takes up far less space than a roundabout would here - you'd need a large circulatory for the volumes.