Highway code rule 259, “Joining the motorway“:
- give priority to traffic already on the motorway
- check the traffic on the motorway and match your speed to fit safely into the traffic flow in the left-hand lane
- not cross solid white lines that separate lanes or use the hard shoulder
- stay on the slip road if it continues as an extra lane on the motorway
- remain in the left-hand lane long enough to adjust to the speed of traffic before considering overtaking.
I don’t know if it’s just a thing where I happen to live, but too many times I see drivers on a slip road joining the main dual carriageway at any-speed-they-like and expecting those on the carriageway to move over or slam on the brakes for them. You know who you are…
You idiots.
That not how it works. It’s up to you to adjust your speed to suit the speed of the traffic on the carriageway, evening coming to a stop if necessary. I don’t recommend coming to stop – you are more likely to get rear-ended, so do your best to match the carriageway speed and be looking for a gap you can safely merge (not barge) into without causing other drives to stamp on the brakes or take evasive action.
I made you a picture in case you’re still not getting it:
In normal driving, yes I do move over for a car joining the slip road where possible, but it’s the expectation of those drivers who think it’s a given multiple people will take action just to accommodate them at that moment. When we all start slowing down because you don’t know how to merge, that’s how we end up with traffic queues and rear-end collisions.