Where is it?
M27 junction 3, where Southampton's bypass and part of the south coast trunk route crosses a short spur motorway, leading to the city and docks.
What's wrong with it?
If you've looked at the junction diagram already you should know. The M271 — not much of a road, but still a motorway — is interrupted by a roundabout. If the route of the M271 is busy enough to warrant a motorway, surely the motorway built there should be built to the correct standards. There's only one actual grade-separated junction on the M271; the other three (this and the termini) are roundabouts. It's a motorway alright, but only because it has an "M".
Why is it wrong?
This should have been the northern end of the M271 — a roundabout is an acceptable ending for a motorway. However, building a junction here on the M27 meant that there wasn't room for another to serve the local area. Rather than making the locals go without, or — god forbid — drive an extra mile to reach the junction on the M271, the planners decided to add a new link road to the A3057. But because this roundabout had motorway restrictions, and the only other connecting roads were motorways, the new spur road had to be a motorway too. So the M271 continues to the north, interrupted by a roundabout. More joined up planning from the people who brought you the A601(M).
What would be better?
If you're going to build a motorway, make it motorway standard. If you can't make it motorway standard, don't make it a motorway. Let's downgrade the M271 to an A-road, since it's wrongly numbered anyway (it should have a number beginning with a 3). That way, it has a valid number and the junctions are up to scratch.
Right to reply
The problem with this junction is the Highways Agency and their incompetence. Firstly white hatching has been painted onto the M27 eastbound entry slip on leaving the roundabout, narrowing two lanes to one-and-a-half before widening again after the bend. Secondly, the traffic lights where the M271 northbound meets the roundabout aren't required as there are very few vehicles heading from the M27 (east of the junction) northbound up the M271. Even in rush hour there are only a handful of vehicles travelling in this direction. Off peak the lights often turn red for traffic heading out of Southampton, in order to let no cars pass through. Maybe Southampton City Council gave them the idea!
This junction makes my morning journey very frustrating. I want to travel up the M271, turning left at this bad junction to travel west on the M27. The M271 is two lanes, both of which become blocked with traffic (cars, lorries leaving the docks and the Nursling Industrial Estate) that wants to turn right to travel east on the M27 and are held up by the roundabout traffic lights and congestion eastbound on the M27. The usual situation is that we sit there in a queue knowing that we would save 5-10 minutes by driving along the hard shoulder to the roundabout (where another lane appears for those turning left onto the M27). On occasions we take an alternative route to junction 1 of the M27 (through Totton on A and B roads) because it takes less time than waiting on the "M"271.
Another amusing why-is-the-M271-a-motorway? story... almost every day I see cyclists riding north along the hard shoulder of the M271 between the Redbridge Roundabout and the Nursling Junction, probably because it's the quickest/shortest route. I've seen the cyclists stopped by the police, but they're still back there the next day.
The reason that this is a bad junction is that Portsmouth city had the sense to fight for the budget for a 'proper' junction [for the M275] as they realised this would make their port more attractive (Southampton no longer has cross channel ferries partly as a result).
Southampton still has a huge container and vehicle terminal, and this junction should attract funding as this is the route for all port traffic, which is set to grow.
Back in March 2006 some changes were made to this bad junction. And to be honest the traffic flow has improved in the early morning rush hour, but I don't have any evidence for a causal link.
* northbound side of the roundabout (over the M27) is now three lanes.
* southbound side of the roundabout (over the M27) is now two lanes, with a new set of traffic lights controlling traffic going straight on (onto M271 towards southampton) or right (onto M27 slip westbound).
* westbound slip off the M27 up to the roundabout now starts earlier, meaning no hard shoulder for some distance on the M27 (a blue sign announces this).
* no longer a dedicated slip at the roundabout from M27 westbound onto M271 southbound - instead all traffic coming off M27 is controlled by traffic light at the top.
* Its still a busy junction, but I think its a little less "bad" than before. I'd give it a bit more time though.
The slip down onto the M27 eastbound is still ridiculous: two lanes off the roundabout go into one before joining the uphill motorway, lots of lorries from the docks & industrial estate... fun and games.
There was never a major problem at this junction, coming from Portsmouth direction, until they added traffic lights. There used to be a dedicated lane to go straight onto the M271 and one for Romsey access. Now everyone has to stop, causing tailbacks onto the motorway which never existed before they decided to "improve" the junction. Madness.