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fras wrote: ↑Thu Dec 10, 2020 23:09
Don't you just love the "its only a few seconds longer at 60 than 70. Then we get 60 to 50, 50 to 40, 40 to 30 and its always "its only a few seconds longer". I can see 40 mph on motorways soon, or will the demented 20 mph zealots get it down to 20 moh ?
The elevated section of the M4 has been 40mph both ways since 1999, when it dropped from 50 mph, it is only a couple of miles long and you don't notice it.
Westbound after the elevated section it is 70mph, but 60mph Eastbound coming into town from J4, which will remain when the ALR is in place to J3. When this was first put in it was a 50mph for the bus lane, but this was raised to 60mph in around 2004. When the bus lane disappeared in 2010, the limit remained at 60mph. As someone who experienced the long queues at the lane drop before the flyover, the 60mph actually reduces the length of the queues as traffic approaches at a slightly slower speed. Work by TRL showed that the 50/40mph arrangement increased average journey times from J4 to J1, but the 60mph/40mph decreased journey times.
IMO you notice when driving a drop from 70mph to 50mph, but a drop to 60mph is very less noticeable.
EpicChef wrote: ↑Fri Dec 11, 2020 09:49
I do like how the MS4s are used for the speed limit on smart-motorway stretches. There's also a message "speed limit reduced for air quality" if I'm not mistaken.
Yes that message was on the signs between M6 J7 and J6 a few days ago. First time I'd seen it.
A fair bit of lorry bashing here, but what alternative do we have? Canals? The railway system could not handle any form of step change in volume or cope with last mile delivery. Beeching called the end to the majority of old fashioned "mixed trains".
I can't see the 60mph restrictions being beneficial, it seems like a backdoor ploy to increase camera revenue. If the trial data includes on the hour updates, maybe it would be be beneficial to see what effects it does have - say to a normal day, but like already commented, the times when figures are high, average speeds are a lot lower than 60mph anyway.
Electric vehicles still cause emissions, the electricity doesn't just appear in the battery and they still use rubber tyres and generally below 20mph slowed by conventional brakes - which will cause some form of emission of material.
Duple wrote: ↑Sun Jan 31, 2021 16:53
A fair bit of lorry bashing here, but what alternative do we have? Canals? The railway system could not handle any form of step change in volume or cope with last mile delivery. Beeching called the end to the majority of old fashioned "mixed trains".
I can't see the 60mph restrictions being beneficial, it seems like a backdoor ploy to increase camera revenue. If the trial data includes on the hour updates, maybe it would be be beneficial to see what effects it does have - say to a normal day, but like already commented, the times when figures are high, average speeds are a lot lower than 60mph anyway.
Electric vehicles still cause emissions, the electricity doesn't just appear in the battery and they still use rubber tyres and generally below 20mph slowed by conventional brakes - which will cause some form of emission of material.
Well, HS2 is going to help improve freight capacity on the rail network
Lower limits can certainly help, how much so is unknown. Also, it could be a backdoor ploy to slightly increase capacity on a busy stretch (I'm not familiar with traffic levels at this trial), as the slower a vehicle's speed, the less spacing between vehicles is required.
About cameras, I don't buy the increasing revenue theory. They are enforcing the law, and as such it is your problem as a driver if you are caught breaking the posted speed limit
About EVs, yes they still emit particulates from the tires and breaks (regenerative braking is the standard in EVs now, which reduces particulates from brakes), but they don't emit gases like CO2 and NOX
A303Chris wrote: ↑Fri Dec 11, 2020 10:09
The elevated section of the M4 has been 40mph both ways since 1999, when it dropped from 50 mph, it is only a couple of miles long and you don't notice it.
Yes you do. When it was 50 the traffic rolled along there nicely at 55 or so, for which the sightlines are fine. Come the 40 limit, with cameras, and nobody seems to even touch 40, the average is about 35. That's a significant drop.
A303Chris wrote: ↑Fri Dec 11, 2020 10:09
The elevated section of the M4 has been 40mph both ways since 1999, when it dropped from 50 mph, it is only a couple of miles long and you don't notice it.
Yes you do. When it was 50 the traffic rolled along there nicely at 55 or so, for which the sightlines are fine. Come the 40 limit, with cameras, and nobody seems to even touch 40, the average is about 35. That's a significant drop.
If it was me I'd expand to three full-width lanes. The viaduct is getting old anyway so needs a refurbishment. And of course the installation of MS4 message boards and AMI signals, with a VSL of upto 70 westbound, or 40-50 eastbound.
Though roads may not put a smile on everyone's face, there is one road that always will: the road to home.
EpicChef wrote: ↑Mon Feb 01, 2021 01:16If it was me I'd expand to three full-width lanes. The viaduct is getting old anyway so needs a refurbishment. And of course the installation of MS4 message boards and AMI signals, with a VSL of upto 70 westbound, or 40-50 eastbound.
That's easier said than done, I think.
The present viaduct has a single line of columns down the middle, with beams cantilevered out to each side supporting the road deck. It requires intensive maintenance as it is, because the concrete is in an appalling state, with netting underneath to catch falling debris before it hits the road below. There's no way it would support the considerable extra strain of a wider road deck, and in any case, to build one you'd have to remove the road deck that is there. You're looking at demolishing virtually all of the existing structure and replacing it.
Even if you were willing to do that, you're still left with the problem of how to support it. Cantilevering out from the middle becomes increasingly problematic with every bit of additional width, so you might need supports down each side, but there are utilities and other services in the verges of the A4 so all of those would have to be relocated first. And with that resolved, you'd then need to address the fact that there isn't really room for a wider viaduct in some places - imagine what you'd subject these houses to if you made the structure even wider.
Lastly, the alignment of the viaduct is entirely dictated by the alignment of the A4 underneath, and the A4 Great West Road at that point was laid out before the First World War. It doesn't have an alignment suitable for 70mph running. One of the curves on the M4 actually has an advisory limit of 30.
EpicChef wrote: ↑Mon Feb 01, 2021 01:16If it was me I'd expand to three full-width lanes. The viaduct is getting old anyway so needs a refurbishment. And of course the installation of MS4 message boards and AMI signals, with a VSL of upto 70 westbound, or 40-50 eastbound.
That's easier said than done, I think.
The present viaduct has a single line of columns down the middle, with beams cantilevered out to each side supporting the road deck. It requires intensive maintenance as it is, because the concrete is in an appalling state, with netting underneath to catch falling debris before it hits the road below. There's no way it would support the considerable extra strain of a wider road deck, and in any case, to build one you'd have to remove the road deck that is there. You're looking at demolishing virtually all of the existing structure and replacing it.
Even if you were willing to do that, you're still left with the problem of how to support it. Cantilevering out from the middle becomes increasingly problematic with every bit of additional width, so you might need supports down each side, but there are utilities and other services in the verges of the A4 so all of those would have to be relocated first. And with that resolved, you'd then need to address the fact that there isn't really room for a wider viaduct in some places - imagine what you'd subject these houses to if you made the structure even wider.
Lastly, the alignment of the viaduct is entirely dictated by the alignment of the A4 underneath, and the A4 Great West Road at that point was laid out before the First World War. It doesn't have an alignment suitable for 70mph running. One of the curves on the M4 actually has an advisory limit of 30.
Hearing that makes me think it might be worth getting rid of the viaduct all together...
We would need to choose an option!
Or possibly build another viaduct to redirect the motorway to a better terminus.
Though roads may not put a smile on everyone's face, there is one road that always will: the road to home.
EpicChef wrote: ↑Mon Feb 01, 2021 01:16If it was me I'd expand to three full-width lanes. The viaduct is getting old anyway so needs a refurbishment. And of course the installation of MS4 message boards and AMI signals, with a VSL of upto 70 westbound, or 40-50 eastbound.
That's easier said than done, I think.
The present viaduct has a single line of columns down the middle, with beams cantilevered out to each side supporting the road deck. It requires intensive maintenance as it is, because the concrete is in an appalling state, with netting underneath to catch falling debris before it hits the road below. There's no way it would support the considerable extra strain of a wider road deck, and in any case, to build one you'd have to remove the road deck that is there. You're looking at demolishing virtually all of the existing structure and replacing it.
Even if you were willing to do that, you're still left with the problem of how to support it. Cantilevering out from the middle becomes increasingly problematic with every bit of additional width, so you might need supports down each side, but there are utilities and other services in the verges of the A4 so all of those would have to be relocated first. And with that resolved, you'd then need to address the fact that there isn't really room for a wider viaduct in some places - imagine what you'd subject these houses to if you made the structure even wider.
Lastly, the alignment of the viaduct is entirely dictated by the alignment of the A4 underneath, and the A4 Great West Road at that point was laid out before the First World War. It doesn't have an alignment suitable for 70mph running. One of the curves on the M4 actually has an advisory limit of 30.
Hearing that makes me think it might be worth getting rid of the viaduct all together...
We would need to choose an option!
Or possibly build another viaduct to redirect the motorway to a better terminus.
The only real solution to replacing the Chiswick Flyover with a free-flow option is to tunnel it from Hogarth Roundabout
Yes, it is expensive, but there is no way that you will get away with replacing the viaduct like for like in the current climate. (putting a toll on it would be an interesting way to do it)
Also, this would open up the A4 to being rebuilt, on the current M4 corridor, into a tree-lined avenue, with cycle lanes and bus lanes (makes everyone happy)
The added bonus, is that you can still use the existing viaduct while a replacement is being built
Duple wrote: ↑Sun Jan 31, 2021 16:53
A fair bit of lorry bashing here, but what alternative do we have? Canals? The railway system could not handle any form of step change in volume or cope with last mile delivery. Beeching called the end to the majority of old fashioned "mixed trains".
I can't see the 60mph restrictions being beneficial, it seems like a backdoor ploy to increase camera revenue. If the trial data includes on the hour updates, maybe it would be be beneficial to see what effects it does have - say to a normal day, but like already commented, the times when figures are high, average speeds are a lot lower than 60mph anyway.
Electric vehicles still cause emissions, the electricity doesn't just appear in the battery and they still use rubber tyres and generally below 20mph slowed by conventional brakes - which will cause some form of emission of material.
While the ECML and WCML are at or close to capacity there are things we can do and are in fact either being done or are being studied. Lets look at some of them.
In Progress
1) East West Rail. This is often described incorrectly as an Oxford to Cambridge passenger service. The reality is that its much more than that. The reinstated/upgraded route will run from Felixstowe to the Thames Valley and is being designed to handle container traffic. The route for the missing section to Cambridge has now been selected.
2) The Durham Coast Line Upgrade from the Tees to the Tyne via Hartlepool, Easington and Sunderland with one branch to Jarrow and the other to Gateshead. There are some odd branches along this line which while not having carried passengers for decades are still open and used for freight. These include the Clarence Line which runs from Port Clarence, passes North of Stockton to meet the ECML at Ferryhill. All these lines are very much underutilised and have the potential to move a lot of freight.
Possibilities:
The same applies to many of the remaining lines in Lincolnshire which with a modest amount of investment in upgraded signalling and perhaps some dualling and bypass lines . Could carry a lot of freight , as they did pre Beeching.
Nobody is going to propose reopening mixed freight service but then we don't need to. Multimodal Container Terminals allow containers to be dropped on to a truck for the last few miles to the local distribution centre. I had to smile when just such a terminal was opened on the site of the old Tees Marshalling Yard at Thornaby with another on the site of the old Middlesbrough Goods Yard and the line to Teesport is being upgraded having been regarded as obsolete when the new section of the A66 was built to reach it.
As a child we lived in a house near Middlesbrough in Wood Street and the background to my infancy was the sound of shunters moving trains around.
What goes around comes around I suppose, it's odd but rather gratifying to see long abandoned facilities like these coming back into use after 50 years of being left to rot. The latest development is a major upgrade of Darlington Station which will not only increase capacity but allows future reopening of the lines to the Durham Coast Line. The first £45 million pounds of funding are already in place. The reality is that rail freight has been growing for years and if anything that growth rate is increasing. You must be dong something right when Stobart are using rail freight.
The 60mph on the M5 J1-J2 is now in place. Some of the signs have room below for a speed camera icon if they want to add it however there are no cameras enforcing the limit.
The super span gantry just past J2 that had nothing on it heading south now finally has a use with three national speed limit signs added to it.
The M602 60 limit is signed with temporary signs, which have a black border around the yellow backing board so not compliant with TSRGD. Quelle surprise.
Bryn Terminally cynical, unimpressed, and nearly Middle Age already. She said life was like a motorway; dull, grey, and long.
Bryn666 wrote: ↑Tue May 25, 2021 09:37
The M602 60 limit is signed with temporary signs, which have a black border around the yellow backing board so not compliant with TSRGD. Quelle surprise.
But it is compliant when done on the VMS on M1 and M6.
Though roads may not put a smile on everyone's face, there is one road that always will: the road to home.
brummie_rob wrote: ↑Tue May 25, 2021 00:54
The 60mph on the M5 J1-J2 is now in place. Some of the signs have room below for a speed camera icon if they want to add it however there are no cameras enforcing the limit.
The super span gantry just past J2 that had nothing on it heading south now finally has a use with three national speed limit signs added to it.
I went through on Saturday northbound and saw most but by no means all of the signs had been uncovered.
Make poetry history.
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EpicChef wrote: ↑Mon Feb 01, 2021 01:16If it was me I'd expand to three full-width lanes. The viaduct is getting old anyway so needs a refurbishment. And of course the installation of MS4 message boards and AMI signals, with a VSL of upto 70 westbound, or 40-50 eastbound.
That's easier said than done, I think.
The present viaduct has a single line of columns down the middle, with beams cantilevered out to each side supporting the road deck. It requires intensive maintenance as it is, because the concrete is in an appalling state, with netting underneath to catch falling debris before it hits the road below. There's no way it would support the considerable extra strain of a wider road deck, and in any case, to build one you'd have to remove the road deck that is there. You're looking at demolishing virtually all of the existing structure and replacing it.
Even if you were willing to do that, you're still left with the problem of how to support it. Cantilevering out from the middle becomes increasingly problematic with every bit of additional width, so you might need supports down each side, but there are utilities and other services in the verges of the A4 so all of those would have to be relocated first. And with that resolved, you'd then need to address the fact that there isn't really room for a wider viaduct in some places - imagine what you'd subject these houses to if you made the structure even wider.
Lastly, the alignment of the viaduct is entirely dictated by the alignment of the A4 underneath, and the A4 Great West Road at that point was laid out before the First World War. It doesn't have an alignment suitable for 70mph running. One of the curves on the M4 actually has an advisory limit of 30.
There's almost certainly room for D4 double deck (ALR) with the pillars on each side rather than in the middle, with the A4 as S4 underneath at ground level between the pillars, like this.
Not that it would be a popular solution, but I can't see a technical obstacle.
There's almost certainly room for D4 double deck (ALR) with the pillars on each side rather than in the middle, with the A4 as S4 underneath at ground level between the pillars, like this.
Not that it would be a popular solution, but I can't see a technical obstacle.
Well maybe but you would have to do a complete rebuild that would disrupt traffic on the A4 and M4 for a prolonged period.
There's almost certainly room for D4 double deck (ALR) with the pillars on each side rather than in the middle, with the A4 as S4 underneath at ground level between the pillars, like this.
Not that it would be a popular solution, but I can't see a technical obstacle.
Well maybe but you would have to do a complete rebuild that would disrupt traffic on the A4 and M4 for a prolonged period.
Oh yes, well any significant change to that would need a complete rebuild. Perhaps it could be done by building the new pillars outside the existing viaduct and the upper deck over it, then demolishing the existing viaduct and building the lower deck.
KeithW wrote: ↑Tue May 25, 2021 23:21
Well maybe but you would have to do a complete rebuild that would disrupt traffic on the A4 and M4 for a prolonged period.
Oh yes, well any significant change to that would need a complete rebuild. Perhaps it could be done by building the new pillars outside the existing viaduct and the upper deck over it, then demolishing the existing viaduct and building the lower deck.
Constructing a new deck over an existing live Motorway which in turn is above the A4 seems impractical to say the least and would be a non starter politically. This is what things look like at ground level. https://www.google.co.uk/maps/@51.49103 ... 8192?hl=en
booshank wrote: ↑Tue May 25, 2021 23:28
Oh yes, well any significant change to that would need a complete rebuild. Perhaps it could be done by building the new pillars outside the existing viaduct and the upper deck over it, then demolishing the existing viaduct and building the lower deck.
That brings you back to the original problem, which is that there’s barely space to put anything outside the width of the existing viaduct, and even if you could do that, all the underground services are buried below the footways of the A4 to get them out of the way of the existing structure. You’d have to move those first, and to where?
EpicChef wrote: ↑Wed May 26, 2021 10:14
Also, how will signage and VMS be fitted on the lower deck?
I think that’s a fairly minor problem with this proposal TBH!
The most obvious thing, if the existing viaduct had to be replaced, would be to put the M4 in tunnel and remove the highly unsatisfactory situation of having it above the A4 altogether.
I’d have a west-facing exit on the surface at Boston Manor leading to the A4, serving traffic for the A4 around Brentford and the South Circular. I’d then bore a dual three lane tunnel from just west of where the viaduct begins. It would split underground into a pair of dual two lane tunnels. One would emerge to join the A4 into London and the other would join the A406.
I’d then hold a SABRE Members’ Walkabout on the viaduct just before it was demolished. There would be a parade, live music, and flying pigs would leave smoke trails across the sky
