M5 - A417
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Ordnance Survey map - Alternative aerial view
Where is it?
M5 junction 11A. The connection between the M5 and M4, taking in Swindon and Cirencester on the way, arrives at the M5.
What's wrong with it?
It's a bit of a tangle really. Some areas have full free-flowing links, some have a roundabout, some have no links at all. The roundabout over the A417 is seemingly unnecessary (one side isn't even used) and the wide sweeping curves, while very nice and graceful, take up a rather astonishing amount of land. The piece de resistance is that (from personal experience at least) the junction tends to have nothing but a couple of cars tootling around the expanse of tarmac.
Why is it wrong?
One assumes that some links are more important than others. Since the A417 forms part of a link to and from the M5 from points south, links to the M5 north are prioritised here. The roundabout can also (perhaps) be explained by what appears to be a new dual carriageway in the aerial photo, under construction there, maybe now finished. Whatever this road serves now has a connection to the junction, though curiously not the A417 westbound.
Several years on, that dual carriageway is now open and the roundabout makes sense. You could still do with a westbound entrance slip, though.
What would be better?
Providing the missing westbound on-slip to the A417 would be a nice start, so at least no movements from the new road have to take in surface streets.
Right to Reply
E-mail me with your comments.
Gazzaa, one of the people responsible for the design of the junction, demolishes my criticisms one by one:
Why isn't it a full movement junction?
If you look at the wider picture you'll note that the M5 junction 11 is just a few kilometres to the north with a high standard 70mph dual carriageway (the A40) linking the towns of Cheltenham and Gloucester to the M5 (north) i.e. there was little point in providing the west to north movement at junction 11A [the same is true of most other missing movements].
There's never any traffic?
I think the main reason you don't think there's any traffic is because the junction is free flowing and therefore you cannot visualise in fact the traffic volume it is quite high, not M25/M4 junction proportions but all the same quite high.
Why isn't there just a normal roundabout and slip roads?
Good question, in the analysis of the junction layouts we did test the twin bridge layout using a computer programme called Arcady ... And it's a good job that we didn't build a twin bridge junction as during peak hours the queues stretch for miles, honest, no joke but sorry it just doesn't work.
Why is it so big?
Well it's not that big, it's not as big as a fully grade separated junction eg. M25/M23 and not as small as a twin bridge junction, it's in between the two, which is exactly what it is, a partial movements partially fully grade separated junction.
Dunc adds:
As I use it to get to and from London, I would have appreciated a better sliproad from the A417 to the M5 north. It's so tight that it's difficult for traffic to get up enough speed to join the motorway properly.
Paul Berry is concerned:
I went through this junction a couple of weeks ago. The reason for the "missing" slip road off the roundabout onto the A417 is because the motorway slip road has already started and there's not enough room to fit it in (without weaving). What does seem to be the biggest problem, which hasn't been touched upon, is there's no northbound motorway access at all to the roundabout junction (and thus the spur to Gloucester Business Park), which seems very strange. Do they only want traffic from Bristol?
Ian is probably best described as irate:
Clearly your motorway designer has never tried to drive around the Gloucester ring road from the south in the rush hour. Access Northbound from the West would reduce the traffic flow on the ring road (which is, incidentally, one of the poorest excuses for a bypass of any city in the country. If he's responsible for that too, I'd like to strangle him).
Kev explains that strange roundabout:
The dual carriageway under construction in the photo [since updated] connects the junction to the Gloucester Business Park. The decision not build a direct northbound access to the M5 here was - as things tend to be in the UK - very shortsighted, as the Business Park is one of the biggest development sites in the south west with many major distribution warehouses established as well as thousands of houses on the way.
