M25 Junction 10 to Junction 16 Smart Motorway

[Jayck]

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?

I think you're right, and it would make some difference remarking the road, I think this is especially true clockwise at M25 J15: 3 lanes through the junction, then half the merging traffic is forced into the three lanes, and only the second lane from the M4 opens out the road to 4 lanes. I can actually put a number on how this affects the capacity, the 4 lane M6 Preston bypass seems to be able to handle ~7,700 vehicles per hour before running into capacity problems, whereas the M25 between J15-16 never runs at flows above 7,200 vehicles per hour (see he HE TRIS data page). Besides differences in proportions of HGV's etc., I imagine this disparity is simply down to the M4 merge choking the M25's capacity. Having said that, it does seem fairly obvious that a simple repaint won't solve the issue entirely, the M25 does need the 5 lanes between the M4 and M40.

[jackal]

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

There's an actual offside exit a couple of junctions along the M25 with no apparent safety issues:

https://www.google.co.uk/maps/@51.46473 ... 384!8i8192

[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

There's an actual offside exit a couple of junctions along the M25 with no apparent safety issues:

https://www.google.co.uk/maps/@51.46473 ... 384!8i8192

… but isn't that *already* segregated from the main M25 carriageway (on the right, beyond the Armco) at this point?

[jackal]

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

There's an actual offside exit a couple of junctions along the M25 with no apparent safety issues:

https://www.google.co.uk/maps/@51.46473 ... 384!8i8192

… but isn't that *already* segregated from the main M25 carriageway (on the right, beyond the Armco) at this point?

Yes, so it's a similar location to Bryn's proposal (which concerns the diverge on the J12 clockwise offslip).

[RichardA35]

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?

It's some 15 years since I proposed exactly that relining for M25 to M3 to give consistency to the signing on the back of the 12-15 widening only to be met with a silence from HA and their agents overseeing the project - and I was a voice from within!

[Bryn666]

I bet you got red line boundary'd.

"Our remit is to widen between J12 and 15... the slip roads are outside of scope blah blah blah"

I got that same treatment when I dared suggest that the other side of the A556/A56 roundabout needed amendments to accept the proposed road markings. It took a Stage 2 safety audit to vindicate my argument

[A303Chris]

A few points on recent posts about outer roads relieving the M25. Any upgrades to the A404 between the M4 and M40 are restricted by the hamlet Bisham under the Wood which is accessed of the Bisham Roundabout here. The hamlet is circa 8 dwellings and all the buildings are listed. When the original Marlow bypass was built between Burchetts Green and Handy Cross the intention was to make this junction grade separated, but even back in the early 70s the implications of flyovers on this Hamlet and the neighbouring village of Bisham another village where every property is listed, was deemed to great. It was built as a local authority road jointly between Buckinghamshire and Berkshire and only became trunked in 1991 when the Maidenhead Thicket bypass between the A4 and A404 was built. Berkshire couldn't wait to hand it over as even then it was seem as problem which would only get worse.

The same with the A3095 Crowthorne / Sandhurst bypass. The original plans were for it to start at the end of the A329(M) pass to the west of Bracknell join the existing route then peel off at Owlsmoor going round the east of College Town and join the A331 and the Blackwater relief road, all being HQDC. The Blackwater relief road was built as HQDC but the A3095 was not. Two reasons implications on Easthamstead Park, Downshire Golf Course and Bracknell crematorium west of Bracknell and the fact it would have gone through the Royal Military Academy at Sandhurst. So we got this half cocked bypass which passes through housing estates at either end.

As discussed on another thread, it is because of the problems on the M25 that the Government is pushing the Oxford , Cambridge expressway as this will provide a HQDC link 50 miles out from the M25 with a continuous route made up of the A34, new link road, A421, A428 and A14 linking the M3, M4, M40, M1, A1(M) and M11. It's what the French do around Paris.

[A9NWIL]

As discussed on another thread, it is because of the problems on the M25 that the Government is pushing the Oxford , Cambridge expressway as this will provide a HQDC link 50 miles out from the M25 with a continuous route made up of the A34, new link road, A421, A428 and A14 linking the M3, M4, M40, M1, A1(M) and M11. It's what the French do around Paris.

Now they just need the southern section going from Winchester connecting the A34 round to Gatwick, Tonbridge, Maidestone then North to meet the south of the planned LTC then somehow round to meet the M11 without using the M25.
It may not be perfect but would remove a massive amount of traffic from the M25!

[mikehindsonevans]

As discussed on another thread, it is because of the problems on the M25 that the Government is pushing the Oxford , Cambridge expressway as this will provide a HQDC link 50 miles out from the M25 with a continuous route made up of the A34, new link road, A421, A428 and A14 linking the M3, M4, M40, M1, A1(M) and M11. It's what the French do around Paris.

Now they just need the southern section going from Winchester connecting the A34 round to Gatwick, Tonbridge, Maidestone then North to meet the south of the planned LTC then somehow round to meet the M11 without using the M25.
It may not be perfect but would remove a massive amount of traffic from the M25!

Well, that's the "southern section" kn**kered by the stalemate at Chichester, then!

[A9NWIL]

As discussed on another thread, it is because of the problems on the M25 that the Government is pushing the Oxford , Cambridge expressway as this will provide a HQDC link 50 miles out from the M25 with a continuous route made up of the A34, new link road, A421, A428 and A14 linking the M3, M4, M40, M1, A1(M) and M11. It's what the French do around Paris.

Now they just need the southern section going from Winchester connecting the A34 round to Gatwick, Tonbridge, Maidestone then North to meet the south of the planned LTC then somehow round to meet the M11 without using the M25.
It may not be perfect but would remove a massive amount of traffic from the M25!

Well, that's the "southern section" kn**kered by the stalemate at Chichester, then!

Why Chichester? thats a long way south of where my proposed outer ring would be?

[Bryn666]

A new motorway across the South Downs NP? Good luck

[thatapanydude]

I would personally prefer work on creating a free flow N.Circular and a LTC at Greenwich. That would go a long way to taking commuter traffic of the northern stretch of M25. Also improving the A414 and A120 to create an alternative route from the M1 to the A12 should be looked at.

To improve the SW part of the M25, I would build a south coast expressway from Brighton to Ashford, then dual the A36 from Southampton to the A303. You could look at a motorway route from the M40 to the A1 (ringway 3) via Pinnar, as you could probably weave something through with small amounts of demolition.

Furthermore, smaller schemes like widening parts of the M25 where space permits such as J12 to J11 to D5(M) (bridges are wide enough), A1 to J24 etc would be useful. I would suggest installing a HS from J23 to J27 would do a lot to improve reliability.

[A303Chris]

A new motorway across the South Downs NP? Good luck

It's hard enough getting a new access in the SDNP park, I know!!!!, let alone a new road

[Bryn666]

Now they just need the southern section going from Winchester connecting the A34 round to Gatwick, Tonbridge, Maidestone then North to meet the south of the planned LTC then somehow round to meet the M11 without using the M25.
It may not be perfect but would remove a massive amount of traffic from the M25!

Well, that's the "southern section" kn**kered by the stalemate at Chichester, then!

Why Chichester? thats a long way south of where my proposed outer ring would be?

Because your proposed outer ring would go through the national park and has 0% chance of happening.

[Berk]

I would personally prefer work on creating a free flow N.Circular and a LTC at Greenwich. That would go a long way to taking commuter traffic of the northern stretch of M25. Also improving the A414 and A120 to create an alternative route from the M1 to the A12 should be looked at.

To improve the SW part of the M25, I would build a south coast expressway from Brighton to Ashford, then dual the A36 from Southampton to the A303. You could look at a motorway route from the M40 to the A1 (ringway 3) via Pinnar, as you could probably weave something through with small amounts of demolition.

Furthermore, smaller schemes like widening parts of the M25 where space permits such as J12 to J11 to D5(M) (bridges are wide enough), A1 to J24 etc would be useful. I would suggest installing a HS from J23 to J27 would do a lot to improve reliability.

So how would these help me to drive from Peterborough to Brighton then?? Or Brighton to Portsmouth and beyond??

I’d rather the south-west quadrant AND the A27 were both fixed. We need capacity all round, not just in specific areas.

[thatapanydude]

I would personally prefer work on creating a free flow N.Circular and a LTC at Greenwich. That would go a long way to taking commuter traffic of the northern stretch of M25. Also improving the A414 and A120 to create an alternative route from the M1 to the A12 should be looked at.

To improve the SW part of the M25, I would build a south coast expressway from Brighton to Ashford, then dual the A36 from Southampton to the A303. You could look at a motorway route from the M40 to the A1 (ringway 3) via Pinnar, as you could probably weave something through with small amounts of demolition.

Furthermore, smaller schemes like widening parts of the M25 where space permits such as J12 to J11 to D5(M) (bridges are wide enough), A1 to J24 etc would be useful. I would suggest installing a HS from J23 to J27 would do a lot to improve reliability.

So how would these help me to drive from Peterborough to Brighton then?? Or Brighton to Portsmouth and beyond??

Because what I proposed takes commuter traffic away from the M25, making it possible for journeys such as Peterborough to Brighton (A1 to M23) to become fast and reliable again.

As I've mentioned a few times, but will repeat again, traffic which shouldn't be using the M25 are because roads in London are bad.
For example, M25 J15 to J12 and the M4 is clogged up with M3 traffic since the A316 fails to provide a fast enough link to Hammersmith. Likewise, M23 traffic is only using the M25 to the A3 or M4 because we fail to provide a decent enough link to London from the South. If the A23 was dualled to Croydon or even Stretham, traffic for C.London wouldn't have to use the A3, A2 or M4. Furthermore, traffic from somewhere like Cambridge to Chiswick is currently left restoring to the M25, where providing provision of an adequate A406, would take commuter traffic away from the M25.

Also another point, building ring roads further out of London will only increase mileages and actually will have negligible if any impact on commuting times for journeys which are (N to S) or (E to W). Cambridge to Southampton would be longer both in mileage and times using the A34 vs M25.

[Berk]

Also another point, building ring roads further out of London will only increase mileages and actually will have negligible if any impact on commuting times for journeys which are (N to S) or (E to W). Cambridge to Southampton would be longer both in mileage and times using the A34 vs M25.

That’s why I’m not sure about how much inner/outer London traffic uses the M25 to cross London?? Then again, just looking at the map you can see we already have some of the Ringway-era links in place (M1/A10/M11), so maybe it’s plausible after all.

But the M25 was never designed to be Ringways 2, 3 and 4 rolled into one...

Everyone who decries the Ringways (‘too expensive, too damaging’), has to face the facts that this has lead to the situation we have got. For the last 30 years, just one major orbital motorway circles our national capital, and it has to service local, and regional as well as long-distance traffic.

In Britain, when you’re talking about infrastructure or public services, it’s a bit like Brexit. All, or nothing. The greens seem to have been so successful at promoting their agenda, we can’t seem to agree on any way forward that involves strategic road construction.

[jackal]

There is cross-London traffic using the M25, just as there is long distance traffic that has nothing much to do with London. But in the SW quadrant at least these are minor components. I think HE said 1% of traffic travels the whole J10-16 distance, for instance. The vast majority of traffic is hopping on and off again within a few junctions, and is essentially local. (The eastern side of the M25 is a little different - e.g., more HGVs in absolute terms, despite having less traffic, on account of the ports.)

Improvements to the A27, North Circular, etc, should be assessed on their own merit. But any benefit for the M25 would be trivial, and swamped by general traffic growth. Realistically if you want to reduce congestion on the M25 SW quadrant you improve the corridor itself, or failing that, provide routes much closer to the M25 with value for local traffic, like the M31.

[Herned]

For example, M25 J15 to J12 and the M4 is clogged up with M3 traffic since the A316 fails to provide a fast enough link to Hammersmith. Likewise, M23 traffic is only using the M25 to the A3 or M4 because we fail to provide a decent enough link to London from the South.

Do you have any data or evidence to support this? The proportion of traffic from the M23 even heading to central London by any route must be an absolutely minute proportion of the traffic on the road. I would love to see some data for the amount of car traffic heading into central London from outside the M25 from any direction. My speculation would be that the largest proportion would be people heading for the City via the A13. And possibly a bit into the west end via the A40. From any other direction it's surely too horrible a journey to contemplate regularly!

As Jackal mentions above, the traffic is much more local, so needs more local solutions. Even something like C/D lanes would be a bit pointless if only 1% of traffic goes the whole length of the route

[A303Chris]

The DfT and HE are stuck between a rock and a hard place since London became a devolved area with the Mayor. Especially the new incumbent who would rip up all roads in the city, the likelihood of any proper improvements with the TfL are long gone. So the M25 has to take cross London Traffic. The A406 could have been a great road but like the recent upgrade at Wood Green, half cock tripe on a grade separated road either side.
How do the French, Germans and Spanish build so many good roads in urban and even areas of outstanding natural beauty, so they have the balls to the economic interests of their county in front of nimbys and greens.