Which lane to enter on this roundabout? (UK)

I’ve lived in the MK area since I was born. My family and I have used this roundabout countless times, and this is how we use it.

If you’re coming at the turn from the M1, and you want to go to:

• A509 — Go in the left lane. Exit the roundabout.
• M1(S) — Go in middle lane. On the roundabout the left lane.
• MK(S) — Go in middle lane. On the roundabout the middle lane.
• A509(S) — Go in the right lane. On the roundabout the right lane.

If you’re coming at the turn from the A509, and you want to go to:

• A509 — Go in the left lane. Exit the roundabout.
• M1(S) — Go in the left lane. On the roundabout the left lane.
• MK(S) — Go in the right lane. On the roundabout the middle lane.
• A509(S) — Go in the right lane. On the roundabout the right lane.

Here is a visual:

On approach to the roundabout you have three lanes:

1. the left most lane, which is a feeder lane to the first exit and thus can be excluded from the answer.
2. the middle lane
3. the right lane

On the roundabout, you have three lanes:

1. The left lane, which goes straight on
2. The middle lane, which goes both straight on and right
3. The right lane, which goes right

The correct answer is that approach lane 2 (the middle lane) goes only to roundabout lane 1 (the left lane) while the approach lane 3 (the right lane) goes to either the roundabout lane 2 or 3 depending on how far around the roundabout the driver intends to go.

Thats the only acceptable use of those lanes.

See on the following image my very skillful depiction in MS paint of the junction with more of the roundabout. The purple line allows you to rejoin the A509 in the direction you came from, if you so wish, as well as allowing you to take the MK exit.

To see the continuation of the yellow and purple lanes, I have followed the roundabout further around for clarity:

As you can see, the lane layout is a nice natural progression around the roundabout, with certain lanes being forced off at particular points, so as I said above, you choose roundabout lane 2 or 3 depending on how far around the roundabout you intend to go.

HOWEVER…

Whilst the above is based on the UK Highway Code, as brhans says in the comments, the green line makes no sense – you are forced back onto the motorway from whence you came…

The road markings on the approach to the roundabout modify the normal rules, and we end up with this:

The road markings never intend for you to choose the left hand lane on the roundabout, they intend for you to take either the middle or the right hand lane.

The left hand lane on the roundabout remains there for people who are already on the roundabout and are coming around to join the motor way in the direction you were travelling.

Regardless of which lane you want to end up in on the roundabout, here’s how I have always interpreted a junction like this:

Whichever direction you’re coming from, if you want to leave the path I’ve laid out by colour coding, you need to indicate and transfer.

So, if you wanted to take the A509(S), you’d:

• approach the roundabout in the right-most lane
• upon reaching the roundabout, continue into what is now the middle lane
• find a safe moment to indicate then cross over into the right-most lane

I wish I had proof that this is correct (and I find that everybody seems to have their own idea about what to do, particularly on the M42 Northbound at Tamworth services — ugh), but it’s what I do and it follows from the curvature of the roundabout’s furniture.

If you are in the left lane on the slip road, the island forces you to go left, signposted Newport Pagnell A509(n). If you go further down the slip road (see image) you can see that the slip road’s middle and right lanes both have access to MK A509(s). So if you are in the middle lane on the slip road, you can go into the left or middle lanes on the roundabout. If you are in the right lane on the slip road, you must take the right lane on the roundabout.

Edit: I found some higher-res satellite imagery, so added image with lanes coloured to indicate what I said above, a bit clearer.

In this particular case I think the right lane should enter the rightmost of the three while the left should enter the center lane of the three.

This is the exit ramp from M1 south, so the only people wanting to get back on M1(S) will be those who’ve made a mistake. The two lanes on the exit ramp are signed for Milton Keynes, so both will want to enter a MK lane. The left lane should use the leftmost MK lane, the right lane the rightmost MK lane. The lane to M1(S) alone could be entered from the left lane but almost no one will want to do that.

The “correct answer” to the question should be on the road signs you have just passed as you approached the roundabout. They should have indicated which of the two lanes to choose for the various exits marked on the road (M1 southbound, MK (Milton Keynes?), and A509 southbound)

The road markings in your second picture are also directions for traffic that is already on the roundabout (coming from the right).

The “general principle” in the UK is that if you are going to pass several several exits before you leave (i.e. you are turning right and staying on the roundabout while you turn through 270 degrees) you enter in the inside lane, and “spiral outwards” to get into the correct lane to leave, as the other traffic exits from the outside lane(s).

There may be more than one lane leaving the roundabout at an exit, depending on the number of lanes on the road away from that exit. At major road junctions (which this one appears to be, from the pictures) the outside lane may only lead to the next exit – i.e. you can’t (officially!) continue on the roundabout if you are in the outside lane.

Since the entrance to the roundabout is controlled by traffic lights, the “easiest” options will be to take the left and right hand lanes on the roundabout, not the central one – but if you are going to MK, you will probably need to move out of the right hand lane soon if you do that.

Which lane you should be in at any point depends on where you want to go to, not where you’ve come from. Where there is more than one lane for your destination, be in the left-most of them unless it’s already full (and you intend to pass the vehicles in it) in which case you can use the next one along.

Left-most lane (separated by the traffic island) turns left onto the A509 (Northbound).

Middle lane can go into the left lane on the roundabout (to go straight ahead, which in this case means back on to the M1 which you just came off) or middle lane on the roundabout (for MK / A509(S) – this is a right turn, but in this case the road markings before your first image indicate that this can be done from the middle lane).

Right-most lane can go into the right or middle lane on the roundabout (for MK / A509(S)).

If you go into the middle lane of the roundabout, be aware that you may not be the only one heading there!