Two Lane Drop Junctions

[jervi]

For the M23 J8 - J10 Smart Motorway Upgrade the M23 is getting a two lane drop at J8 with the M25, Highway England called this "non-standard". This got me thinking about what other two (or more) lane drops exists in the UK. Not including the ones where an extra lane on the left appears shortly before the diverge.
Currently I can only think of a few:
* M1 / A1(M) J43 - Arguably when heading southbound the A1(M) takes 1 lane which splits into three, therefore the course of the road drops 1 lane (on the left), but drops 3 if you think it isn't a TOTSO. Either Way it is more non-standard than a two lane drop.
* M3 J2 - Eastbound only
* M3 J9 - Proposed to have two lane drop onto A34 in upcoming works.
* M23 J8 - Southbound (current goes from 4 lanes for the short and incomplete section to 2 lanes over the junction, however this wasn't its original layout if you look at the positions of the displays over the lanes at the diverge and the double width shoulders)
* M23 J8 - Northbound as currently being built during the Smart Motorway scheme.
* M25 J5
* M25 J14 - ACW Only, part of the mess at Heathrow
* M25 J15 - CW Only, part of the mess at Heathrow
* M27 J4 - Eastbound Only
This list is far from complete, do you have any to add?
What do you think of two lane drops?

[Johnathan404]

Non-standard doesn't mean uncommon! Recent widenings have created lots of them:

* M27 J4 westbound once the work is complete
* M42 J7a southbound and J9 (twice) northbound
* M42 J3a southbound
* M6 J11a southbound
* M6 J8 southbound when the hard shoulder is in use
* M6 J6 southbound when the hard shoulder is in use
* M6 J3a northbound when the work is complete, I believe
* M60/M62 J12
* M4 J20 westbound
* arguably the A34 between the A339 and the M4
* M6 J32 has lost it but the M55 still does it, if you're accepting termini

...off the top of my head. I've left out examples where the middle lane widens to two, or where it's a link road with a right-hand exit.

[ellandback]

M62 j29, although it gets them back again immediately afterwards (eastbound subject to HSR).

[JosephA22]

M40 J1a eastbound, drops 2 lanes for the M25.

[Micro The Maniac]

M25(ACW) J12 for the M3

[Chris5156]

M1 J42, in both directions
M1 J43

[paranoid]

A1(M) J57 for A66(M) is signed, but not lined, as a double lane drop... https://www.google.co.uk/maps/@54.49362 ... 312!8i6656

(I'm pretty sure it used to be marked as 4 lanes, but Streetview goes back to 2010 and it wasn't then...)

[alice]

Depending on your definition of "shortly before" (there are 4 lanes for a good kilometer before the drop though) the A31 Eastbound/A338 junction at Ringwood

[djw1981]

M74 J6 southbound.

[jackal]

M25 anti-clockwise has a triple lane drop to the M4. Offhand I can't think of any more of these on grade separated roads.

[Johnathan404]

M25 anti-clockwise has a triple lane drop to the M4. Offhand I can't think of any more of these on grade separated roads.

It's the only example where three running lanes are dropped, because realistically you'd need a D5 or D6 to do it and we don't have many of those.

There are a few examples where the exit is three lanes wide before it splits, like Simister, Hook Moor and the old Catthorpe. I appreciate it's not what the OP wanted, but they are impressive in their own right.

I suppose it's also cheating if we give examples away from the classified road network, like at Heathrow Terminal 2.

[jackal]

M25 anti-clockwise has a triple lane drop to the M4. Offhand I can't think of any more of these on grade separated roads.

It's the only example where three running lanes are dropped, because realistically you'd need a D5 or D6 to do it and we don't have many of those.

Indeed, that would be the normal situation, though you could plausibly have a triple drop on a D4 where turning movements dominate. This was a possibility for the M3 ALR scheme, eastbound at the M25. There is really only one lane's worth of traffic going through the junction (as shown by the single lane westbound) so they could have had a triple drop. They instead went for a double lane drop plus a tigertail, which is eminently sensible, though takes a little more space and may not always be an option.

[DB617]

M25 anti-clockwise has a triple lane drop to the M4. Offhand I can't think of any more of these on grade separated roads.

It's the only example where three running lanes are dropped, because realistically you'd need a D5 or D6 to do it and we don't have many of those.

There are a few examples where the exit is three lanes wide before it splits, like Simister, Hook Moor and the old Catthorpe. I appreciate it's not what the OP wanted, but they are impressive in their own right.

I suppose it's also cheating if we give examples away from the classified road network, like at Heathrow Terminal 2.

Good grief, I've never driven through and had never closely examined that junction. The number of merge in arrows on the right-turn movements makes me totally unsurprised that there are constant accidents on this junction!

[thatapanydude]

In London the A12 southbound drops 2 lanes for the A11 at Bow and also the A1 drops 2 nearside lanes at Fireways corner with lane 3 joining the M1.

[Duple]

M6 Jnc 4A southbound I guess technically fits this ?

[JonH]

M3 J2 eastbound, 2 lane drop for Heathrow/CW M25. All the Gatwick/ACW M25 traffic has to use Lane 3 and the slip road. When the traffic backs up on the ACW as it is prone to do, Lane 2 of the Heathrow bit becomes rather dicey.

[Rob590]

A1/A1(M)/A174(M) northbound at Washington is a split of D4 into two D2s.

[trickstat]

In London the A12 southbound drops 2 lanes for the A11 at Bow and also the A1 drops 2 nearside lanes at Fireways corner with lane 3 joining the M1.

The latter is a bit of an oddity because the A1 actually does a TOTSO to duplex with the A41 up to Apex Corner. The 2 dropped lanes are the A1.

[Johnathan404]

Speaking of D5s, there is of course a triple lane drop/lane gain at M2/M5 in Northern Ireland (but it's a totso) and a double lane drop/triple lane gain at York Street (but it's a terminus).

The M1 in the Republic has a double lane drop for the M50.

[JosephA22]

In London the A12 southbound drops 2 lanes for the A11 at Bow and also the A1 drops 2 nearside lanes at Fireways corner with lane 3 joining the M1.

The latter is a bit of an oddity because the A1 actually does a TOTSO to duplex with the A41 up to Apex Corner. The 2 dropped lanes are the A1.

Almost like it's actually an offside single lane drop...