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I recall a publicity briefing from HA around 2011-2012 covering the entire M3 corridor (may have been even earlier), which spoke about the need for a northbound crawler lane (ie four complete running lanes) up the Twyford Down cutting northbound from the J11 onslip to J10 where the A31 exits just over the brow of the hill. I recall a potential date of "2018-2019" but may be completely off my trolley on this one.
Purely coincidentally, I noticed last Friday that someone has done a very neat job northbound in cutting back the undergrowth on the verge approaching J10, and trimmed up the fallen chalk.
There are two schemes in RIS1 (i.e. construction to start by 2020) on this section of M3:
M3 Junctions 9-14 – upgrading the M3
to Smart Motorway between junction 9
(Winchester/A34 interchange) and
junction 14 (M27), linking with the Smart
Motorway scheme on the M27.
M3 Junctions 10-11 improved
sliproads – improvements to the most
pressured sliproads on junctions 10 and
11 near Winchester.
That's the point, if retaining the current configuration of junctions, an extra lane is required between junctions 10 and 11 due to the gradients and short distance between the junctions. Whether that is extra in relation to D3M or extra in relation to D4M makes no difference; it's the junctions creating a greater problem than purely the width of the motorway.
Back in the mid-1980s, campaigners against the M3 extension argued that the motorway would soon fill to capacity. They were bang on about that, but the motorway still needed to happen. I stick true to my belief that the final solution was compromised though, and that the compromise is a significant cause of the current congestion seen. And I truly believe that plans for a D4M in the form of a smart motorway on the M3 will help alleviate congestion on the Winchester to Southampton corridor, although I guarantee they will very soon fill up especially once Junction 9 is sorted, and even more so once the A34 in Oxfordshire and West Berkshire is unplugged further into the future, but without extra lanes on top of this through Twyford Down, Twyford Down will remain a congestion hotspot.
It is worth noting that the configuration of the southbound onslip at J10 has already been changed in recent years from single lane entry to two lanes with a ghost island, but the problems persist.
sotonsteve wrote:That's the point, if retaining the current configuration of junctions, an extra lane is required between junctions 10 and 11 due to the gradients and short distance between the junctions. Whether that is extra in relation to D3M or extra in relation to D4M makes no difference; it's the junctions creating a greater problem than purely the width of the motorway.
...
It is worth noting that the configuration of the southbound onslip at J10 has already been changed in recent years from single lane entry to two lanes with a ghost island, but the problems persist.
In what ways?? I think you've hit the nail on the head. Most motorways would not allow junctions so close together. Just look at the latest A1(M) in N Yorkshire. Having a J10 as well as J11 is more akin to A-road junction spacing.
Given this a little more thought. Is the section between J9 and J10 elevated?? Or above ground level, at least. There doesn't seem to be any need for the A34 to connect directly with the motorway at this point. Why not... have the northbound A34 come off the motorway at J10, whilst also building a new limited-access junction (call it 9a), just about opposite the A31 roundabout on the other side - with an underpass connecting them. Make 9a and 10 part of the same, longer junction. Make an enclosed dc - no junctions/connections with other roads.
Let it flow seamlessly onto the old bypass adjacent to J9. Meanwhile, the southbound A34 should be flown over to join the 'A31' on the other side (again, just south of J9). Let them multiplex as far as J10, where motorway traffic can join there. I'm only suggesting J10 because it's already there, but if you were to look at all the junctions, perhaps they can be repurposed/redesigned appropriately.
I realise this may be recreating some aspects of the old bypass, but it's not on purpose. I just don't feel the A34 needs to intersect with any roads other than where they join the motorway. If you make current J9 as good as redundant, you can effectively close it. Although that would also have the effect of denying traffic on Easton Lane from joining the A34/A31. And yes, there may be some land acquisition, possible demolition involved.
But you've basically got the A31 and A34 in a multiplex between J9/9a and 10. Would that be any good??
What would be the advantage of having the a34 join the M3 at 10 rather than 9? The topography around 9 is far better for creating a freeflow link to the A34 than 10 is, being constrained by the gradients approaching Twyford Down. Also you would have to widen the cutting at Spitfire bridge in order to fit a d2 alongside the M3. Much better to keep the intersection of A34 and M3 in the vacinity of J9.
That said removing the need for local connections at 9 would be desirable. If access to/from Winnal and the Spitfire Link to the M3 could be relocated elsewhere, either further north or back to 10 then the roundabout and sliproad configuration could be replaced with a simple overbridge for non motorway traffic and a freeflow fork for the A34 (A34(M)?). The obstacle to this is J10, it would need redesigning/repositioning to provide north facing sliproads.
As sotonsteve said J11 could be solved by providing an LAR between 11 and (see above) 10. Not along the old bypass route as suggested (would never get permission) but through the cutting itself. The cutting and the motorway running through it could be redesigned to run an S2 alongside the motorway, replacing the steep southfacing sliproads of J11. another (less disruptive) option would be to make single lane C/D roads either side of the M3 though the cutting connecting J10 and J11 and replacing 2 sets of sliproads and providing a connection for local traffic. This might be a better option than widenting to D4M.
The s/bnd merge at J10 was originally 2 lanes then, narrowed to 1. This caused long slow queues behind lorries crawling up the steep slip and cars leaping out onto the M3 too early. The second lane was re-instated. The merge was then extended at least 3 times, possibly 4, right up to the summit, an implicit acknowledgement that the hill is the wrong place for a merge.
I've been meaning to write to HE with my 'solution' since they were the HA but, haven't quite got around to it. So anyway, the merge should be at the A31 rbt from the east. The curve would be about the same tightness as the current one but, on the level. The merge would allow a quicker build up of speed, before joining the M3. There would be more conflict at that rbt but, none at the previous one which would be removed and replaced by normal D2.
Perhaps those on here with direct connections could mention it, save me the bother. Pretend it was your idea and get the glory, just send me the money.
Earlier versions of the above, now on view in Roadhog.
Last edited by SteveA30 on Fri Jan 27, 2017 07:45, edited 2 times in total.
I suppose repositioning the SB on slip at 10 so it goes straight up the hill wouldn't help? Run it parallel to Morestead Rd to merge near the top. Steep but not as steep as NB j11 and not on the turn as the current one. Could even add a filter lane to bypass the roundabout so big stuff doesnt have to stop for the roundabout. Would this work or make things worse?
I think it funny (or ironic at least), that the bypass was the cause of so many problems it became necessary to replace it, that it's still causing problems even now, 20-odd years after it's gone.
I figure that even if the motorway took the best possible route across the down, it was stymied by being shoehorned into the old bypass footprint. Had the Twyford cutting been a little wider, and perhaps the old bypass kept as an LAR - even with reservations - perhaps we wouldn't be asking these questions now??
Berk wrote:I think it funny (or ironic at least), that the bypass was the cause of so many problems it became necessary to replace it, that it's still causing problems even now, 20-odd years after it's gone.
I figure that even if the motorway took the best possible route across the down, it was stymied by being shoehorned into the old bypass footprint. Had the Twyford cutting been a little wider, and perhaps the old bypass kept as an LAR - even with reservations - perhaps we wouldn't be asking these questions now??
There was even less chance of the A33 being retained than there was of the A3 at Hindhead. Remember the option of an online upgrade to the A33 was ruled out as being too polluting and disruptive. Once that had happened the A33 was the biggest bargaining chip the government had, with essentially no value to the government anyway.
I didn't want to believe my Dad was stealing from his job as a road worker. But when I got home, all the signs were there.
Sometimes there is a syndrome in the UK with roads that get upgraded first get subsequent upgrades last.
Let me explain. The Winchester Bypass was essentially the first bit of dual carriageway on the London to Southampton route. The rest of the route was upgraded much later, and until the rest of the route was upgraded things worked fine, but once "complete" as a dualled express route it became the weakest link. Fortunately in this case the Winchester Bypass was replaced by the M3. How about the A34 at Oxford? It was one of the earliest bits of A34 to be dualled, and for years worked perfectly fine, but since the A34 was "complete" as a dualled express route it too became the weakest link. And then there is the A3 through Guildford. It was one of the earlier bypasses, and one of the first sections of A3 to be dualled beyond the Kingston Bypass. For years it was fine, but as the rest of the A3 came to be upgraded Guildford became the weakest link.
That's the trouble with piecemeal upgrades; the congestion can get shifted to the bit that was upgraded furthest back in history, and what used to be the best bit of road becomes the worst, because of government trying to squeeze all the blood out of what already exists. And when a road becomes a bottleneck, an upgrade tends to take the form of adding a single extra lane in each direction, when in some cases the bottleneck is so problematic that two extra lanes are needed in each direction. I don't think the planners of the M3 between Winchester and Southampton considered how busy the road would become once Winchester and Newbury were unplugged and the A34 became a fully dualled expressway link to the midlands. It's as if traffic modelling was based on upgrades elsewhere not happening, whereas once Newbury was sorted, that was it, the A34 was destined to fill right up.
Very true. Temple A30 is another example. In the case of the A34, the M40 opened the floodgates there, putting ever more pressure on Newbury and after that, Chievely. Stonehenge also, used to be one of the better stretches. Now with D2 on both sides and, new camera technology for out of the window snaps, it is the top A303 problem.
I recall there being an option to route the M3 west of Winchester, which would have prevented all these problems, as well as the environmental concerns at the time of its construction.
There were a number of routes considered for taking the M3 from Popham to Southampton, both east and west of the current route. In the end, they plumped for the option that most closely followed the existing road and tied in with the Chandlers Ford and Otterbourne Bypass that was completed in 1967.
Wouldn't they just, and with the M3 picking up the strategic traffic the A33 dual carriageway between Winchester, Eastleigh and Southampton would have ended up being the commuter route between these settlements.
M27 J3 would have been quite the dogleg if going between the M3 at Winchester and northern Southampton or east of there (i.e. most of the urban area). I expect the A33 between the Winchester area and Southampton would have remained a de facto strategic route, largely defeating the purpose of the M3.
I'm also far from convinced that the Redbridge roundabout has the excess capacity necessary to accommodate the M3 terminating there.
There are usually good reasons why the schemes that were actually built were built.
The issue with Southampton is not as bad as is made out.
A significant portion of the M3's flow is already coming from either the A31 (especially during the holiday season) or the docks via the M271 (the main growth area). Unfortunately there appears to be an error in the traffic counts, but it is clear that the M27 west and east branches of the M3 carry very similar flows.
I would add anecdotally that when it's busy leaving the M27 westbound for the M3, there is always a significant slow-down as the M27 eastbound joins, despite it being a double lane-gain, caused by the volume of traffic merging which looks very heavy.
All of this suggests, if you were to give it 25 years for traffic and the local economy to get used to it, a route west of Winchester would not have been a bad thing. However, if it's only the Twyford Down decision we're criticising, then much of the damage had already been done: everything was already geared towards Winchester's bypass being on the east. More importantly, you couldn't hijack the route of the M271 without rebuilding it properly.
As far as alternative M3 routes go, does the A3 corridor have any merit? Maybe not all the way to Guildford and Kingston, but following the line of the A3 so far then diverting towards the A30 near Camberley?
The original purpose of the M3 was to relieve the A30, and of course a lot of traffic on the A30 was from/to the A303. Those facts determined its approximate route as far as its original terminus at J8.
wrinkly wrote:The original purpose of the M3 was to relieve the A30, and of course a lot of traffic on the A30 was from/to the A303. Those facts determined its approximate route as far as its original terminus at J8.
Which is fair enough. But it could've remained as motorway, multiplexing with the A303 for a few miles, before taking a more southerly course.
In fact, if it had done that, and met with the M271, the last couple of miles of M27 westbound wouldn't have been necessary (or just been A31(M) instead.
I can't help thinking that would've made better sense?? Than shoving all Southampton traffic down past Winchester, mixed in with the local commuter traffic, and arriving at Bassett - so everyone has to either drive through the city, or the long way round to the docks.
Pretend it was your idea and get the glory, just send me the money. 
