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jackal wrote: ↑Wed May 04, 2022 16:59
Regents Road generally is just a big planning failure. You could argue that it's deliberate, to deter commuting, but when you've been trying deterrence for 40 years with an artificial bottleneck between two decent roads, and all you get is queues, maybe it's time to try something else.
Until now they had the option of putting in GSJs at either end and the A5066, closing/liloing everything else. But I see residential towers "with parking available" are going up right where the A5066 GSJ would be, which won't exactly help matters...
In the 80s when it was planned it was more than adequate for the anticipated traffic. Manchester was a dying city at the time, industry had gone, and the residential population of the central area could be counted on both hands. It only got built because of ongoing slum clearance in Salford - the old road was a S4 flanked with houses and shops, this was never going to work with a motorway slamming into it. I don't think it was ever proposed as much beyond what was built and if it was it would have been prioritised to throw you onto the inner ring road instead of Link 17/7 (aka A57(M)). This is why the west end of the Mancunian Way was a roundabout with a flyover across the A56 route for so long.
Until about 1999 there was still a single carriageway under the railway lines so you had a massive bottleneck for years even after the A56 underpass was built.
The city has changed now, the city centre population including all the new towers being thrown up in Ordsall, cannot continue to accommodate mass driving - Manchester city centre now has a population of 18,000 and a population density of 4,720 per sq. km. GSJs that will only encourage more driving are not the answer inside the M60, unless they are specifically constructed to facilitate other modes - e.g. my right turn flyover at Trinity Way to properly allow space for pedestrian and cycle signal stages to be included instead of the at-grade cluster we currently have.
Bryn Terminally cynical, unimpressed, and nearly Middle Age already. She said life was like a motorway; dull, grey, and long.
DB617 wrote: ↑Wed May 04, 2022 14:00
There definitely is some work to do on poorly timed (or indeed faulty) signalisations. From the research I've been doing to try and find some signage guidance for throughabouts, I stumbled upon a passage in LTN 1/09 which showed why part time lights for peaktime congestion have fallen out of favour, and it's quite justifiably pedestrian facilities. Without the lights being full time, it's difficult to fully and safely accommodate pedestrians. I don't think we have provision in the UK for signals that are part time but can also switch on off-time when a pedestrian is waiting to cross? That leads us to the need for 24/7 lights that should be programmed and constructed well enough to allow them to be essentially a non-factor during the times of day when congestion was never an issue. This is all within our grasp, as other users and engineers have said above, but it needs to be done properly by every authority and then properly maintained, which I can imagine is difficult at present given some cannot seem to even afford relining of roads which have turned into an expanse of blank tarmac (looking at you, South Glos).
The answer is quite simple - grade separate the NMU movements. However this is expensive and that isn't allowed because people (including some in this very thread) complain about wasting money on any things that aren't "brum brum drive fast".
Retrofitting grade separation for NMUs is a very difficult thing to get right because of the space required to build ramps, the severance ramps cause, the visual impact of the ramps, the personal safety issues caused by long structures with limited routes off in a threatening situation, and the sheer cost of building them.
I agree that if designed in from the outset, grade separation can work but it is not a good solution in many places. In the last few years, I've written more reports advising against footbridges, compared with promoting new pedestrian bridges and subways. And yes, I currently have a project for a new subway where we are making it spacious, and building it as a part of a wider public realm project.
Simon
Definitely difficult to retrofit but there's no excuse on new build estates. It's also surely always going to be cheaper to raise a proposed road 3 metres above a proposed cycle/pedestrian route than it is to raise an existing footpath 5+ metres above an existing road. Central Milton Keynes remains a good example of how you do it in planned communities.
Bryn Terminally cynical, unimpressed, and nearly Middle Age already. She said life was like a motorway; dull, grey, and long.
The answer is quite simple - grade separate the NMU movements. However this is expensive and that isn't allowed because people (including some in this very thread) complain about wasting money on any things that aren't "brum brum drive fast".
Retrofitting grade separation for NMUs is a very difficult thing to get right because of the space required to build ramps, the severance ramps cause, the visual impact of the ramps, the personal safety issues caused by long structures with limited routes off in a threatening situation, and the sheer cost of building them.
I agree that if designed in from the outset, grade separation can work but it is not a good solution in many places. In the last few years, I've written more reports advising against footbridges, compared with promoting new pedestrian bridges and subways. And yes, I currently have a project for a new subway where we are making it spacious, and building it as a part of a wider public realm project.
Simon
Definitely difficult to retrofit but there's no excuse on new build estates. It's also surely always going to be cheaper to raise a proposed road 3 metres above a proposed cycle/pedestrian route than it is to raise an existing footpath 5+ metres above an existing road. Central Milton Keynes remains a good example of how you do it in planned communities.
Agreed. There are a number of subways in Welwyn Garden City linking housing areas under main roads. Some of them are narrower than I would like, but in terms of level, they do exactly what you describe.
Simon
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jackal wrote: ↑Wed May 04, 2022 17:50
One of the options for Sheriffhall had some of the most extensive NMU grade separation I've seen:
As this roundabout is quite rural with low NMU usage it's arguably more a sop to the Greens than anything.
On the contrary - it's forward thinking and moving away from car dependency and car dominance. You now don't need to put signals on the roundabout either for pedestrians and slot them into tiny gaps in sequencing, so it will never be a barrier to towns on the other side of the bypass.
Bryn Terminally cynical, unimpressed, and nearly Middle Age already. She said life was like a motorway; dull, grey, and long.
Bryn666 wrote: ↑Wed May 04, 2022 14:48
Meanwhile, in the real world, I have actual useful schemes to design that factor in more than you and your solitary car that must never be held up at a single traffic signal.
OK Bryn, you are always right and everyone else is always wrong.
jackal wrote: ↑Wed May 04, 2022 09:16That said, I expect that the poor performance of these particular schemes is predominantly due to signalisation of roundabouts. I agree with Bryn, Chris and others that conventional signalised junctions would perform better in most cases.
I've just been through the list at the end of that document and don't immediately recognise what was done at each of the locations, but from a scan through it, the ones I do recognise are often signalisation or otherwise tinkering at an existing roundabout, and none involved replacement of a roundabout with a conventional signalised junction. Certainly it's true that the Pinch Point Programme involved a fair number of schemes that signalised and bowdlerised roundabouts. It would be interesting to know if any of them actually did involve reconstruction to conventional signals, and whether the scores for those schemes were any better or worse than the others.
jackal wrote: ↑Wed May 04, 2022 17:50
One of the options for Sheriffhall had some of the most extensive NMU grade separation I've seen:
As this roundabout is quite rural with low NMU usage it's arguably more a sop to the Greens than anything.
On the contrary - it's forward thinking and moving away from car dependency and car dominance. You now don't need to put signals on the roundabout either for pedestrians and slot them into tiny gaps in sequencing, so it will never be a barrier to towns on the other side of the bypass.
Yeah - provision for cycling in that general direction out of Edinburgh is really poor and the severance caused by the bypass really doesn't help. Sheriffhall is the most obvious route for many (just as it is for motor traffic) but acts as a big deterrent. A good AT solution here, even it isn't initially well linked-up to other routes, will be transformational. The junction feels very distant from the city centre offices, but is actually less than 20 minutes cycle away from both the Edinburgh Royal Infirmary and Spire Shawfair private hospital, amongst other things. The Park & Ride is very close too. Carless commuting for Dalkeith-dwelling doctors is perfectly plausible.
jackal wrote: ↑Wed May 04, 2022 09:16That said, I expect that the poor performance of these particular schemes is predominantly due to signalisation of roundabouts. I agree with Bryn, Chris and others that conventional signalised junctions would perform better in most cases.
I've just been through the list at the end of that document and don't immediately recognise what was done at each of the locations, but from a scan through it, the ones I do recognise are often signalisation or otherwise tinkering at an existing roundabout, and none involved replacement of a roundabout with a conventional signalised junction. Certainly it's true that the Pinch Point Programme involved a fair number of schemes that signalised and bowdlerised roundabouts. It would be interesting to know if any of them actually did involve reconstruction to conventional signals, and whether the scores for those schemes were any better or worse than the others.
I haven't looked at the pinch point schemes either, but I can say with certainty that there are places where I think it would be beneficial to remove a roundabout and replace it with signals. However this is can be a much more expensive option than simply signalising the roundabout.
I've said it before. Scheme design is much more about compromise than technical excellence. If you are prepared to pay for it you can have the best scheme. But it might be the only thing you do that year. There is a finite pot of money and those resources need to be spread across a wide area.
Consequently we are stuck with spending a little bit of money to stick a plaster over one problem in each of a lot of different places rather than paying a lot of money for surgery that will completely cure one problem while other problems fester elsewhere.
Simon
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Peter Freeman wrote: ↑Tue May 03, 2022 15:48
^ But - are signals installed without road-embedded detectors on each lane of each approach?
Properly designed junctions all have detector loops or microwave detection. Sites running fixed time are because there is a fault somewhere which either has been reported to the relevant UTMC or hasn't.
Very few, if any, junctions are built today to run fixed time and nothing else. It's another SABRE myth posted without any fact checking.
If that's a SABRE myth then a lot of signalised roundabouts must be faulty and don't ever seem to get repaired - it's very noticeable in the early hours of the morning when there's little traffic about.
I believe many signals engineers prefer to set the signals to 'quiescent red' during the middle of the night when traffic flows are minimal. That is, instead of endlessly cycling through each stage, all phases are set to red until a demand is detected. This is to prevent those drivers who are out at night 'chasing greens', initially, if they have sense, they are going to slow down for the red signal, which should then go green once they are within the detection zone.
Hopefully, resting on all red should also prevent those drivers who 'amber gamble', insisting that no other traffic is about at that time of day, from coming to grief with the driver from a conflicting arm who is thinking the exact same thing.
M4Simon wrote: ↑Thu May 05, 2022 12:47...I haven't looked at the pinch point schemes either, but I can say with certainty that there are places where I think it would be beneficial to remove a roundabout and replace it with signals. However this is can be a much more expensive option than simply signalising the roundabout.
I've said it before. Scheme design is much more about compromise than technical excellence. If you are prepared to pay for it you can have the best scheme. But it might be the only thing you do that year. There is a finite pot of money and those resources need to be spread across a wide area.
Consequently we are stuck with spending a little bit of money to stick a plaster over one problem in each of a lot of different places rather than paying a lot of money for surgery that will completely cure one problem while other problems fester elsewhere.
Simon
This reminded me that the output of the initial design work usually involves looking at a range of congestion flows and the differing extents of infrastructure to cater for these flows before taking an economic decision of the best balance between cost and congestion which can vary depending on the Client.
Quite often the design only deals with the 100th or 150th worst peak hour flow at design year as that is all that is affordable (as land acquisition is usually not considered).
One recent scheme that I was involved with had the traffic signals design based upon opening year traffic as there was so much uncertainty about future developments (hence traffic) and the attitude (at the time) was "others will pay".
Properly designed junctions all have detector loops or microwave detection. Sites running fixed time are because there is a fault somewhere which either has been reported to the relevant UTMC or hasn't.
Very few, if any, junctions are built today to run fixed time and nothing else. It's another SABRE myth posted without any fact checking.
If that's a SABRE myth then a lot of signalised roundabouts must be faulty and don't ever seem to get repaired - it's very noticeable in the early hours of the morning when there's little traffic about.
I believe many signals engineers prefer to set the signals to 'quiescent red' during the middle of the night when traffic flows are minimal. That is, instead of endlessly cycling through each stage, all phases are set to red until a demand is detected. This is to prevent those drivers who are out at night 'chasing greens', initially, if they have sense, they are going to slow down for the red signal, which should then go green once they are within the detection zone.
Hopefully, resting on all red should also prevent those drivers who 'amber gamble', insisting that no other traffic is about at that time of day, from coming to grief with the driver from a conflicting arm who is thinking the exact same thing.
I must have a mystic transmitter on my car! At silly o'clock, the A5/A38 signalised roundabout at Weeford often seems to be Green as I approach but change to Red before I get there, despite no other traffic around making me wait a full cycle for the next Green - particularly annoying when towing as every stop-start costs fuel - and emissions!
Ruperts Trooper wrote: ↑Tue May 03, 2022 19:55
If that's a SABRE myth then a lot of signalised roundabouts must be faulty and don't ever seem to get repaired - it's very noticeable in the early hours of the morning when there's little traffic about.
I believe many signals engineers prefer to set the signals to 'quiescent red' during the middle of the night when traffic flows are minimal. That is, instead of endlessly cycling through each stage, all phases are set to red until a demand is detected. This is to prevent those drivers who are out at night 'chasing greens', initially, if they have sense, they are going to slow down for the red signal, which should then go green once they are within the detection zone.
Hopefully, resting on all red should also prevent those drivers who 'amber gamble', insisting that no other traffic is about at that time of day, from coming to grief with the driver from a conflicting arm who is thinking the exact same thing.
I must have a mystic transmitter on my car! At silly o'clock, the A5/A38 signalised roundabout at Weeford often seems to be Green as I approach but change to Red before I get there, despite no other traffic around making me wait a full cycle for the next Green - particularly annoying when towing as every stop-start costs fuel - and emissions!
Sounds like someone cocked up the MOVA settings as that's the exact opposite of what they're supposed to do in such situations, unless there's a setting that thinks you're approaching too fast and it shows you a red as a result. I'd suggest a word in the local National Highways shell might be worthwhile there.
Bryn Terminally cynical, unimpressed, and nearly Middle Age already. She said life was like a motorway; dull, grey, and long.
jackal wrote: ↑Wed May 04, 2022 17:50
One of the options for Sheriffhall had some of the most extensive NMU grade separation I've seen:
As this roundabout is quite rural with low NMU usage it's arguably more a sop to the Greens than anything.
On the contrary - it's forward thinking and moving away from car dependency and car dominance. You now don't need to put signals on the roundabout either for pedestrians and slot them into tiny gaps in sequencing, so it will never be a barrier to towns on the other side of the bypass.
I can vouch for the truth of this. On my cycle commute into Gothenburg, the cycle path goes over or under all the major roads on the outskirts. It's only once you get into the densely built city that cyclists (and pedestrians) have to mess around with complicated signalised junctions that invariably involve more than one set of lights to clear the whole junction. The biscuit is well and truly taken at one particular location, where the bus has one set of lights to pass from one side of a square to another, while I have two tram crossings and two road carriageway crossings, all with separate sets of lights. It's therefore possible to get four reds in the space of about 50 metres. And people wonder why cyclists don't respect traffic lights.
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Much the same seems to happen at night on the A449 at the three sets of lights between Gailey and Coven. They seem determined to stop all traffic for a short while. Its like Staffordshire Council have stumbled upon a new method of traffic calming !
Make poetry history.
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Big L wrote: ↑Thu May 05, 2022 16:50
Much the same seems to happen at night on the A449 at the three sets of lights between Gailey and Coven. They seem determined to stop all traffic for a short while. Its like Staffordshire Council have stumbled upon a new method of traffic calming !
The A449 between Gailey and Fordhouses is a Trunk Road, so blame The National Highways Agency for England. Although to be fair, Staffordshire CC are generally appalling with their roads, so I can see where the thought came from.
Steven
Motorway Historian
Founder Member, SABRE ex-Presidents' Corner
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The A358/A38 junction in Taunton was built as a roundabout. It was converted to a signal-controlled crossroads with non-controlled left turns in the early-1990s.
It's very busy now, and the original proposal to upgrade it was to turn it into a hamburger, with the turning movements handled by a circulatory carriageway around the central crossroads. Common sense prevailed and it is being expanded as a normal signal-controlled junction.
Debaser wrote: ↑Thu May 05, 2022 13:02
I believe many signals engineers prefer to set the signals to 'quiescent red' during the middle of the night when traffic flows are minimal. That is, instead of endlessly cycling through each stage, all phases are set to red until a demand is detected. This is to prevent those drivers who are out at night 'chasing greens', initially, if they have sense, they are going to slow down for the red signal, which should then go green once they are within the detection zone.
Hopefully, resting on all red should also prevent those drivers who 'amber gamble', insisting that no other traffic is about at that time of day, from coming to grief with the driver from a conflicting arm who is thinking the exact same thing.
Is this fact or supposition? I find it hard to believe it would be official policy. I've noticed nothing like this in the city I live in, which overwhelmingly uses signals instead of roundabouts and has several thousand signalised locations. The rest status favours the major flow. If travelling on the main through roads of Melbourne, in the dead of night, most signals will be on green as you approach and pass through.
Ruperts Trooper wrote: ↑Thu May 05, 2022 16:22
I must have a mystic transmitter on my car! At silly o'clock, the A5/A38 signalised roundabout at Weeford often seems to be Green as I approach but change to Red before I get there, despite no other traffic around making me wait a full cycle for the next Green - particularly annoying when towing as every stop-start costs fuel - and emissions!
Big L wrote: ↑Thu May 05, 2022 16:50
Much the same seems to happen at night on the A449 at the three sets of lights between Gailey and Coven. They seem determined to stop all traffic for a short while. Its like Staffordshire Council have stumbled upon a new method of traffic calming !
I don't know whether these comments were meant seriously. Surely these are cases of the well-known phenomenon where you only remember unfavourable instances, and not the favourable ones? Similar to how, in parallel queues to the bank tellers, it always seems that the queue you've randomly chosen moves more slowly than all the rest.
Debaser wrote: ↑Thu May 05, 2022 13:02
I believe many signals engineers prefer to set the signals to 'quiescent red' during the middle of the night when traffic flows are minimal. That is, instead of endlessly cycling through each stage, all phases are set to red until a demand is detected. This is to prevent those drivers who are out at night 'chasing greens', initially, if they have sense, they are going to slow down for the red signal, which should then go green once they are within the detection zone.
Hopefully, resting on all red should also prevent those drivers who 'amber gamble', insisting that no other traffic is about at that time of day, from coming to grief with the driver from a conflicting arm who is thinking the exact same thing.
Is this fact or supposition? I find it hard to believe it would be official policy. I've noticed nothing like this in the city I live in, which overwhelmingly uses signals instead of roundabouts and has several thousand signalised locations. The rest status favours the major flow. If travelling on the main through roads of Melbourne, in the dead of night, most signals will be on green as you approach and pass through.
Ruperts Trooper wrote: ↑Thu May 05, 2022 16:22
I must have a mystic transmitter on my car! At silly o'clock, the A5/A38 signalised roundabout at Weeford often seems to be Green as I approach but change to Red before I get there, despite no other traffic around making me wait a full cycle for the next Green - particularly annoying when towing as every stop-start costs fuel - and emissions!
Big L wrote: ↑Thu May 05, 2022 16:50
Much the same seems to happen at night on the A449 at the three sets of lights between Gailey and Coven. They seem determined to stop all traffic for a short while. Its like Staffordshire Council have stumbled upon a new method of traffic calming !
I don't know whether these comments were meant seriously. Surely these are cases of the well-known phenomenon where you only remember unfavourable instances, and not the favourable ones? Similar to how, in parallel queues to the bank tellers, it always seems that the queue you've randomly chosen moves more slowly than all the rest.
But given this was over 10 years ago what has happened in terms of guidance from the government (which hasn't really changed)?
New standards, best practice guidance?
Or has it disappeared without trace?
Was it a civil service exercise for the government to be seen to pander to the motoring lobby?
