Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

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jackal
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Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by jackal »

http://www.highways.gov.uk/roads/road-p ... nterchange
Highways England wrote:We will introduce variable mandatory speed limits (via overhead electronic signs and signals on the M62 eastbound carriageway), and traffic lights on the link roads which connect the M6 (northbound and southbound) at junction 21A to the eastbound carriageway of the M62 junction 10 Croft Interchange.
:shock:
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by A9NWIL »

jackal wrote:http://www.highways.gov.uk/roads/road-p ... nterchange
Highways England wrote:We will introduce variable mandatory speed limits (via overhead electronic signs and signals on the M62 eastbound carriageway), and traffic lights on the link roads which connect the M6 (northbound and southbound) at junction 21A to the eastbound carriageway of the M62 junction 10 Croft Interchange.
:shock:
Is this a government 'we want to slow motorways down?
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by Bryn666 »

Given that the M62/M6 junction jams up in all directions every day this might go some way to sorting it.

It is basically advanced ramp metering so rule out any signals on the mainlines.
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by wrinkly »

Hooray, I've found the old thread for this!

Further press release:

https://www.gov.uk/government/news/test ... rway-trial
Tests have begun this week on an innovative, pilot project designed to reduce congestion along the M62 near Warrington in Cheshire.

Highways England is delivering the project at Croft Interchange - where junction 21a of the M6 meets junction 10 of the M62 – to give drivers smoother and more reliable journeys along the eastbound M62, one of the busiest commuter congestion hotspots in the region.

When the testing is completed in December / January, electronic information signs and variable mandatory speed limits on the M62, will combine with traffic lights on the motorway link roads from the M6, to provide smoother traffic flows.
For more see the link.
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by Peter Freeman »

Melbourne Australia introduced ramp metering on its urban motorways several years ago. This is of the "one vehicle per green per lane" drip-feed type, with the on-ramp splayed to 2, 3 or 4 lanes at the signal. There are now 50 to 60 of these sites, most of them bi-directional. A few sites provide a bypass lane for trucks, buses and taxis.

The first implementations used a standalone algorithm (known as 'Alinea'), sensing only its own ramp and relevant mainline section, and controlling only its own on-ramp. Now, however, the intersections are linked for long distances using an over-arching algorithm (known as 'Hero'). It allows a metered intersection to recruit assistance from its upstream neighbours if its own ramp queue over-extends, or if local mainline flow-breakdown persists despite the metering. This produces the effect, confusing for upstream users, of ramp signalling being on for no apparent reason.

The system is fully operational on smart-motorways M1, M2 and M80, and works well (though I have some slight reservations). By the way, there is a rather similar scheme on the main N-S motorway and others in Auckland NZ.

A current Melbourne project (planned completion early 2018) that is widening part of MI from 2x4 to 2x5 lanes and smartifying will add metering on both connectors from M3 Eastlink. This is similar to the UK's M62J10 proposal. I am rather wary of this development, but it will be interesting to see how it works out. M2M is also about to be switched on at the extremely busy merge-point of M2 southbound to M1 eastbound, close to Melbourne's tunnel under the city. The 3-lane signal point is so far along the connector that it feels like it's signalling half of the mainline! I've also seen an imminent plan for M2M metering somewhere in Perth, Western Australia.

I'll report back when these M2M's are operational - perhaps on the International Roads forum. And I'll be interested to hear how the M62J10 installation pans out.
Last edited by Peter Freeman on Fri Apr 09, 2021 10:37, edited 1 time in total.
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by jackal »

In the UK motorways thread on skyscrapercity there are several examples of freeflow ramp metering in the US as well as a former scheme in the Netherlands that was removed when the capacity constraint was lifted with widening. I can't help but think they should have tried that here with cheap and cheerful ALR on the M62 eastbound before resorting to signals.
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by WHBM »

Ramp metering is no novelty in the USA, I recall it was extensively in use in Los Angeles 40 years ago, generally with a bypass lane for any "carpool", which was actually any vehicle with at least one passenger, and it surprised me how seemingly more than 80% of vehicles did not. Sometimes a CHP policeman would hide behind a sign and leap out into the live bypass lane to stop and ticket any violator, right there on the ramp. Would undoubtedly fail H&S over here !

There was a widespread but misguided belief that the system somehow "spotted" gaps in the mainline traffic flow and signalled you out accordingly.

However this was all on ramps from city streets, not on high speed inter-freeway connectors. I can't equate this M62 proposal with the general concept that motorways don't have traffic lights. Though of course there are other instances of them, including on the mainline, here already.

I was surprised in Cleveland, Ohio, which had them on inner-suburb freeway entrances, that general urban decline had reached such an extent, both in the local neighbourhood and on the freeway mainline as well, that they were withdrawn as no longer necessary.
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by Stevie D »

WHBM wrote:However this was all on ramps from city streets, not on high speed inter-freeway connectors. I can't equate this M62 proposal with the general concept that motorways don't have traffic lights.
That seems to be the big difference. Ramp metering causes traffic on the slip roads to back up – that's bad enough if it pushes interference back onto local roads or a roundabout interchange, but if it is potentially going to cause traffic to back up onto another motorway mainline, it does start to feel like you could be robbing Peter to pay Paul.
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by wrinkly »

At the M6/M62 interchange there's about 1km of slip road for traffic to back up on before it reaches the M6 mainline.

Incidentally I see Landranger mapping still shows the slip roads from the east and westbound M62 merging with each other before they merge with the southbound M6. That stopped being the case when the M6 was widened to D4M between the M62 and M56 in the 1990s.
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by jackal »

Here are some quotes from Skyscrapercity to give international perspective:
ChrisZwolle wrote:While ramp metering is common in quite a number of countries, it seems extremely rare on free flow motorway-to-motorway interchanges. The Netherlands experimented with it on the A15/A50 interchange, but it was removed after A50 was expanded to eight lanes.

Though metering is pretty common at tunnels, even when there is no capacity reduction.
keokiracer wrote:US-101 to SR-85 on the southside of San Jose, California. I'm not sure if it's actually in use, but it's there.

edit: the other on-ramp in that interchange in the same direction has one too.
Jschmuck wrote:In Milwaukee, WI on I-94 interchange with WI-341. The ramps from WI-341 to I-94 have meters. WI-341 is not a long major freeway however its interchange with I-94 is totally free flow and high speed (high speed if there weren't any meters).
So it seems M2M ramp metering was formerly used in the Netherlands, is currently used in the US, and will soon be in use in the UK and (as per Peter above) Australia.
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by Peter Freeman »

jackal wrote:In the UK motorways thread on skyscrapercity there are several examples of freeflow ramp metering in the US as well as a former scheme in the Netherlands that was removed when the capacity constraint was lifted with widening.
Do those threads indicate whether the M2M metering was deemed to be successful?
jackal wrote: I can't help but think they should have tried that here with cheap and cheerful ALR on the M62 eastbound before resorting to signals.
I fully agree. Here, one M3-to-M1 ramp adds a lane to make a 5-lane no-HS stretch, which has filled up all the right-of-way and under-bridge widths. But the other merges onto a D4M which could easily be, and eventually will be, widened.
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by jackal »

Peter Freeman wrote:
jackal wrote:In the UK motorways thread on skyscrapercity there are several examples of freeflow ramp metering in the US as well as a former scheme in the Netherlands that was removed when the capacity constraint was lifted with widening.
Do those threads indicate whether the M2M metering was deemed to be successful?

I've added the relevant quotes above. The issue of 'success' is not addressed, aside from the fact that in the Netherlands example it clearly wasn't the long term solution.
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by Peter Freeman »

Stevie D wrote:Ramp metering causes traffic on the slip roads to back up – that's bad enough if it pushes interference back onto local roads or a roundabout interchange, ...
Yes, that's the problem. Here in Melbourne, the controlling algorithm uses a sensor at the top of the on-ramp to indicate that the storage is full, and then releases the queue to avoid local road interference. However, it doesn't work perfectly, so I frequently observe ramp queues blocking right and left turns and even non-entering through traffic at the feeding signal point.
Stevie D wrote: ... but if it is potentially going to cause traffic to back up onto another motorway mainline, it does start to feel like you could be robbing Peter to pay Paul.
Yes, exactly. The queue release (or speed-up) mechanism in that case will be critical.

Both these potential problems are theoretically solvable/manageable, but in practise - let's see.
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by WHBM »

Well if the algorithm-setter is the one who does the HE-maintained roundabout signals at M25 J28 (A12) and M25 J30 (A13) then there's no hope.
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by darkcape »

The ramp-metering schemes I've come across in the UK usually have loops at the top of the slip road to stop the queue stacking back to the junction, and usually give longer greens when the mainline is moving - it's not uncommon to see them permanently on green whilst the mainline is moving and then return to drip-feeding once the mainline slows up.

I don't think it's a big deal them being used on motorway-to motorway slip roads - other junctions such as M6 J5 you can easily be doing 70mph by the time you reach the signals.
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by Bryn666 »

The weird thing is the loop from the M6N to M62E is a lane gain anyway. The problem is there is insufficient capacity further along at everyone's favourite trouble spot... M60 J12. It backs all the way up to Warrington regularly.

Most of the traffic problems in the NW would be resolved by fixing the M60 it seems...
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by jackal »

This is one spot that would particularly benefit from the mooted M58 extension.

In the short term they could at least try adding the fourth lane between J10 and J11. It's a rather obvious case of four going into three.
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by WHBM »

darkcape wrote:The ramp-metering schemes I've come across in the UK usually have loops at the top of the slip road to stop the queue stacking back to the junction.
This seems somewhat counter-intuitive. I understood the purpose of the meters was to increase capacity, by avoiding too many going down the ramp at once, being unable to merge, stopping, and then creating difficulties for both ramp and mainline capacity by needing to get going from a standing start.

If the loop at the top detects traffic backed up all the way back, then switching the meter off, or to more green, will surely only increase the propensity for this to happen, reduce the flow, and cause blocking back into the roundabout etc even quicker.
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Re: Motorway to motorway (M2M) metering pilot scheme M62 junction 10 (Croft Interchange)

Post by Peter Freeman »

WHBM wrote:
darkcape wrote:The ramp-metering schemes I've come across in the UK usually have loops at the top of the slip road to stop the queue stacking back to the junction.
This seems somewhat counter-intuitive. I understood the purpose of the meters was to increase capacity, by avoiding too many going down the ramp at once, being unable to merge, stopping, and then creating difficulties for both ramp and mainline capacity by needing to get going from a standing start.

If the loop at the top detects traffic backed up all the way back, then switching the meter off, or to more green, will surely only increase the propensity for this to happen, reduce the flow, and cause blocking back into the roundabout etc even quicker.
Your comment regarding the effect of triggered ramp-queue release or addition of ramp-green-time is correct, and would seem to make such action irrational. In practise it is the right thing to do for the following reasons -
1. Transferring the congestion problem onto local roads is very undesirable. If the metering remains unaltered, that local congestion gradually spreads out from the ramp-top, and can even affect traffic that doesn't have any interest in the freeway. Effectively you get 'the cure becoming worse than the disease'.
2. In a 'Hero-coordinated' system, the next-upstream ramp metering (or more) will by that time have been invoked, so the original site has time to stabilise and re-start. Under the new flow condition, it might cope better.
3. In my first post in this thread I noted that, despite supporting the Melbourne scheme, I have some reservations. One of them is that I observe metering to be effective over only a limited range of conditions. At incipient mainline breakdown, and consequent switch-on, it works. It continues to work for increasing flows, but eventually it cannot prevent the inevitable mainline queuing to the bottleneck ahead. From that time the ramp traffic does queue at the merge-point, despite being metered: the meter may as well give up and switch off. I think that, under this condition, there is no point in persisting, but in Melbourne it does persist, so the designers here obviously disagree with me on this point!
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