M25 Junction 10 to Junction 16 Smart Motorway

[Chris Bertram]

• Upgrading the A404/A404(M) to full motorway rules from the M40 to the M4

Oh, how I could have used that improvement in the days when I made regular trips between Birmingham and Woking. But it's harder than you think. The Thames Valley forms a significant depression between Handy Cross and Burchett's Green, and the inclines on the A404 either side are steeper than would be allowed on a motorway. So a simple on-line upgrade would be out of the question, I think, and whatever route was taken would probably include a high level viaduct over the river. That's when it starts to look prohibitively expensive.

[jackal]

The page states:

A separate strategic study is looking at longer term options to improve the performance of the transport network between junctions 10 and 16 of the M25.

If this is indeed a "strategic" study, hopefully it will rule out just adding more lanes to the M25, and put serious consideration to both of:

• Upgrading the A404/A404(M) to full motorway rules from the M40 to the M4
• Extending the A329(M) south from the M4 around the west of Bracknell then, either/both of
  • along Old Wokingham Road, Foresters Way (A3095) to pick up the A331 to the M3 and A31, or/and
  • around to the A322, between Guildford and Woking, south of Wisley airfield before they build on it, to pick up the M25 just east of the new Cobham Services
  You could call this the M31 ?
• Upgrading the A34 from Winchester to Wendlebury to D3M as a minimum

Perhaps I need to go a few doors down, to the Fantasy forum?

The study was long since completed, and was a bit of a disaster zone: viewtopic.php?f=1&t=36095&p=897229#p897229
See also this thread on subsequent research, which is more competent and specific: viewtopic.php?f=1&t=38991

[A9NWIL]

The page states:

A separate strategic study is looking at longer term options to improve the performance of the transport network between junctions 10 and 16 of the M25.

If this is indeed a "strategic" study, hopefully it will rule out just adding more lanes to the M25, and put serious consideration to both of:

• Upgrading the A404/A404(M) to full motorway rules from the M40 to the M4
• Extending the A329(M) south from the M4 around the west of Bracknell then, either/both of
  • along Old Wokingham Road, Foresters Way (A3095) to pick up the A331 to the M3 and A31, or/and
  • around to the A322, between Guildford and Woking, south of Wisley airfield before they build on it, to pick up the M25 just east of the new Cobham Services
  You could call this the M31 ?
• Upgrading the A34 from Winchester to Wendlebury to D3M as a minimum

Perhaps I need to go a few doors down, to the Fantasy forum?

Not to me that makes sense to have a more western route even if slightly broken up into chunks. TBH an outer ring would be better something that could run round via Gatwick and link up with the planned LTC motorway. Then you just need a northern route.
The M25 is over capacity, so new lines that bypass the M25 well outside London would remove the long distance traffic from the M25.

[Chris5156]

That's a pity if so, there's something frustratingly short-termist about the M25 strategy.

It's very definitely so - you can't convert the hard shoulder into a running lane through things like this.

I'm not sure I'd describe the J10-16 Smart Motorway scheme as short termist; it's really doing everything that it's possible to do in a short timeframe. If you set your heart on proper widening, that will require extra land take and extensive reconstruction of bridges over and under the motorway - requiring huge investment and causing a level of disruption that will be fought tooth and nail by the well-to-do neighbours of the M25 in this area and which would take years and years to progress to construction, if it ever reached construction at all, which is not a given. Indeed the reason the hard shoulder keeps disappearing on this stretch is that the fourth lane was created in the early 1990s as cheaply and simply as possible, because previous plans to create a four-carriageway motorway with inner express lanes and outer local lanes was abandoned in the face of extremely hostile opposition. Squeezing a fourth lane through the existing bridges was as daring as it was possible to be here in the early 90s.

In light of that, removing the three-lane bottlenecks through interchanges will do a huge amount to relieve congestion on this section of the M25 and has the benefit that it can be done now, without a public inquiry, and for an affordable price tag. It doesn't prevent anything more being done to increase capacity in future. So rather than short termism, I'd call that pragmatism!

[jackal]

That's a pity if so, there's something frustratingly short-termist about the M25 strategy.

It's very definitely so - you can't convert the hard shoulder into a running lane through things like this.
previous plans to create a four-carriageway motorway with inner express lanes and outer local lanes was abandoned in the face of extremely hostile opposition.

Did anyone ever post these plans? I've asked before to no avail.

[ColinB]

I agree 4 lanes through J11 makes sense but not J10 & 12. Surely the amount of traffic using these junctions means they need the lane drops. In fact the WB exit at J12 and the EB exit at J10 could do with the addition of a diverge from lane 2. I do not see how a simple taper diverge will cope.

[jackal]

^ It's absurd really. The M3 drops two lanes but they want to have the M25 dropping zero lanes? Do they think the traffic turning off the M3 just swirls around the whirlpool and then goes back onto the M3?

[Jayck]

^ It's absurd really. The M3 drops two lanes but they want to have the M25 dropping zero lanes? Do they think the traffic turning off the M3 just swirls around the whirlpool and then goes back onto the M3?

Fair point, in fact the M3 drops 2 full lanes *and* has a taper for a third onto the whirlpool. Similarly, it gains 3 entire lanes westbound, which only illustrates your point further.

[Chris5156]

^ It's absurd really. The M3 drops two lanes but they want to have the M25 dropping zero lanes? Do they think the traffic turning off the M3 just swirls around the whirlpool and then goes back onto the M3?

I'll happily agree that I don't understand the thinking, but I'm willing to be persuaded that there is method to the madness, if someone can explain it to me.

Certainly right now the anticlockwise exit to the M3 suffers because exiting traffic has to get into a single lane; making it a tiger tail diverge so M3 traffic can exit from lanes 1 and 2 would probably help. Removing the lane drop so it's just an exit from lane 1 seems retrograde.

I wonder if there's some cart-before-horse logic that says the traffic flows through the interchange are sufficient to justify four lanes, so four lanes will be provided, and solving the merge and diverge problems either side is a job for a future project.

[Patrick Harper]

I predict that J15-J16 is the only place now where any sort of physical widening is feasible and would deliver a tangible benefit.

[jackal]

^ It's absurd really. The M3 drops two lanes but they want to have the M25 dropping zero lanes? Do they think the traffic turning off the M3 just swirls around the whirlpool and then goes back onto the M3?

I'll happily agree that I don't understand the thinking, but I'm willing to be persuaded that there is method to the madness, if someone can explain it to me.

Certainly right now the anticlockwise exit to the M3 suffers because exiting traffic has to get into a single lane; making it a tiger tail diverge so M3 traffic can exit from lanes 1 and 2 would probably help. Removing the lane drop so it's just an exit from lane 1 seems retrograde.

J11-J12 could easily be made five lane ALR as it has continuous hard shoulders.* Add a tiger tail diverge as you suggest and four lanes through J12 would start to make sense.

*Well okay, one of them drops at the J12 diverge, but it doesn't impact the ALR as there are five lanes through that bit already.

[Jayck]

J11-J12 could easily be made five lane ALR as it has continuous hard shoulders.* Add a tiger tail diverge as you suggest and four lanes through J12 would start to make sense.

*Well okay, one of them drops at the J12 diverge, but it doesn't impact the ALR as there are five lanes through that bit already.

I believe I read in the RIS2 study interim report that they've ruled out further widening beyond this scheme, but they add an aside that J10-12 could "always be made all lane running if necessary". I'd have to dig it out for the exact wording.

[jackal]

J11-J12 could easily be made five lane ALR as it has continuous hard shoulders.* Add a tiger tail diverge as you suggest and four lanes through J12 would start to make sense.

*Well okay, one of them drops at the J12 diverge, but it doesn't impact the ALR as there are five lanes through that bit already.

I believe I read in the RIS2 study interim report that they've ruled out further widening beyond this scheme, but they add an aside that J10-12 could "always be made all lane running if necessary". I'd have to dig it out for the exact wording.

I don't recall anything like that. J10-11 is not the simple job that J11-12 would be as there would be many structures needing replacement.

In many ways J10-11 is the straw that broke the camel's back, as it's the only section of J10-16 that's hard to get to five or more lanes.

[Berk]

That's a pity if so, there's something frustratingly short-termist about the M25 strategy.

It's very definitely so - you can't convert the hard shoulder into a running lane through things like this.

I take it you mean in terms of lane drops through junctions??

I'm not sure I'd describe the J10-16 Smart Motorway scheme as short termist; it's really doing everything that it's possible to do in a short timeframe. If you set your heart on proper widening, that will require extra land take and extensive reconstruction of bridges over and under the motorway - requiring huge investment and causing a level of disruption that will be fought tooth and nail by the well-to-do neighbours of the M25 in this area and which would take years and years to progress to construction, if it ever reached construction at all, which is not a given. Indeed the reason the hard shoulder keeps disappearing on this stretch is that the fourth lane was created in the early 1990s as cheaply and simply as possible, because previous plans to create a four-carriageway motorway with inner express lanes and outer local lanes was abandoned in the face of extremely hostile opposition. Squeezing a fourth lane through the existing bridges was as daring as it was possible to be here in the early 90s.

In light of that, removing the three-lane bottlenecks through interchanges will do a huge amount to relieve congestion on this section of the M25 and has the benefit that it can be done now, without a public inquiry, and for an affordable price tag. It doesn't prevent anything more being done to increase capacity in future. So rather than short termism, I'd call that pragmatism!

If we leave aside the zero-sum arguments against widening for a moment, and assume that smartening is the best way to go, what’s wrong with “tactical widening” around junctions, targeted, small-scale so they don’t have to have those lane drops??

Is that what you’d argue for?? If smartening works, fine (it can work, on a good day), so why not make it better by adding some more capacity so those junctions work to the best of their potential??

[Berk]

I still think in the long-term (20-30+ years ahead), a new “Ringway 4” motorway will be needed. Because by the stage the M25 will be unable to cope, and all easy options (such as smartening) will either have been taken, or exhausted.

The new motorway would have to have strictly limited junctions, or access to them, only interfacing with the most major roads (M1/3/4/11/23/40 +A1(M)/A2), and ideally you would try and limit access to those from the M25 as well.

Make it a motorway-motorway-only link. I also think a new northbound Dartford Bridge will be required.

[Truvelo]

Where would a new Ringway 4 go? In 30 years time places like Guildford, Woking and Leatherhead will be a part of Greater London with the land in between completely developed and a two bedroom terraced house in the area will be several million £.

[Berk]

Yes, it would’ve been easier to build nearer the time, when the land was less developed.

But it will have to go somewhere, or the M25 will not function.

[Chris5156]

That's a pity if so, there's something frustratingly short-termist about the M25 strategy.

It's very definitely so - you can't convert the hard shoulder into a running lane through things like this.

I take it you mean in terms of lane drops through junctions??

No, I mean in terms of converting the hard shoulder to a running lane throughout M25 J10-16, which is what Jayck wanted to see and which isn't possible, because of things like the example I posted.

The bridges within the interchanges in question are not built in the same way, and the hard shoulder is unobstructed, so hard shoulder running through junctions is possible, and that's what will be installed.

I'm not sure I'd describe the J10-16 Smart Motorway scheme as short termist; it's really doing everything that it's possible to do in a short timeframe. If you set your heart on proper widening, that will require extra land take and extensive reconstruction of bridges over and under the motorway - requiring huge investment and causing a level of disruption that will be fought tooth and nail by the well-to-do neighbours of the M25 in this area and which would take years and years to progress to construction, if it ever reached construction at all, which is not a given. Indeed the reason the hard shoulder keeps disappearing on this stretch is that the fourth lane was created in the early 1990s as cheaply and simply as possible, because previous plans to create a four-carriageway motorway with inner express lanes and outer local lanes was abandoned in the face of extremely hostile opposition. Squeezing a fourth lane through the existing bridges was as daring as it was possible to be here in the early 90s.

In light of that, removing the three-lane bottlenecks through interchanges will do a huge amount to relieve congestion on this section of the M25 and has the benefit that it can be done now, without a public inquiry, and for an affordable price tag. It doesn't prevent anything more being done to increase capacity in future. So rather than short termism, I'd call that pragmatism!

If we leave aside the zero-sum arguments against widening for a moment, and assume that smartening is the best way to go, what’s wrong with “tactical widening” around junctions, targeted, small-scale so they don’t have to have those lane drops??

There's nothing wrong with it, if the proportion of traffic exiting is not so great that the lane drop is justified. At J11, the lane drop is not justified and hard shoulder running through the junction will eliminate it, in turn easing the all-day congestion there. That's fine. At J12, the lane drop is entirely justified by the amount of traffic exiting - so it's not clear what will be achieved by removing it.

[Bryn666]

J12 is a classic example of bad lane markings causing congestion. HE will spend millions on civils when a few thousand spent on thermoplastic would solve much of the problem overnight.

Clockwise it should be a tigertail, with a non-standard remarking of the London-bound slip to be a fake offside exit (e.g. instead of the new lane appearing on the left as present, it should appear on the right) - there will be no safety problem with this, it's just ridiculous risk aversion to bottleneck traffic and cause a genuine hazard (rear shunts) out of fear of a lane appearing on the right confusing a coffin dodger.

Anti-clockwise the same problem, two lanes exit to the M3 and 50% of that capacity is wasted by directing it all towards Richmond. Why is it not a simple diverge here instead of a lane split? You could maintain two continuous lanes from the M25 anti-clockwise to the M3 if this was done.

Likewise, M3 inbound forces one lane for the M25 anti-clockwise, which is then widened to two, and then back to one because of all the millions of vehicles that don't come from Richmond having an entire lane gain.

We have enough carriageway space to sort many problems without physical widening but there doesn't appear to be anyone bright enough to figure it out. What on earth is going on?

[mikehindsonevans]

J12 is a classic example of bad lane markings causing congestion. HE will spend millions on civils when a few thousand spent on thermoplastic would solve much of the problem overnight.

Clockwise it should be a tigertail, with a non-standard remarking of the London-bound slip to be a fake offside exit (e.g. instead of the new lane appearing on the left as present, it should appear on the right) - there will be no safety problem with this, it's just ridiculous risk aversion to bottleneck traffic and cause a genuine hazard (rear shunts) out of fear of a lane appearing on the right confusing a coffin dodger.

Anti-clockwise the same problem, two lanes exit to the M3 and 50% of that capacity is wasted by directing it all towards Richmond. Why is it not a simple diverge here instead of a lane split? You could maintain two continuous lanes from the M25 anti-clockwise to the M3 if this was done.

Likewise, M3 inbound forces one lane for the M25 anti-clockwise, which is then widened to two, and then back to one because of all the millions of vehicles that don't come from Richmond having an entire lane gain.

We have enough carriageway space to sort many problems without physical widening but there doesn't appear to be anyone bright enough to figure it out. What on earth is going on?

Feel free to trial this on the A34 for the first mile north of the A34/M3J9 junction east of Winchester.

Here, we have the ludicrous situation of two lanes of motorway traffic leaving the M3N/B approaching the roundabout at j9, being told to "use both lanes for A34", then being confronted by a "get into left lane by default" squeeze, because the off-side lane (of two) handles the trickle of traffic heading for the old A33 up to Kings Worthy/Alresford/Springvale.

Madness - and entirely amenable to being ameliorated with (as Bryn opines) "a bit of thermoplastic paint". Surely we don't have to wait until 2023 (M3J9 rebuild) to correct this piece of road-marking stupidity?