L5 Hamburger roundabout expert needed to tinker with this roundabout in West Drayton just north of Heathrow? It generates the odd UR and there is one there at present. I would ask for it to be downlocked but think it would be better for a L5 who has experience with these roundabouts to do it directly.
I don't think there are any major problems but some of the things I've picked up are:
1. The slip road segment I have linked to above is connected to the off slip from the north side of the A408! Therefore Waze actually directs you exit the roundabout and then drive 6.5 feet the wrong way up a slip road and then turn right . Surely it should be connected directly to the roundabout.
2. The geometry on these two segments is not correct. They cause a turn left instruction after exiting the roundabout.
Comments / Discussion points.
I have always considered this as a roundabout with a cut through and never had a problem with it but probably don't listen to the Waze instructions as I know it well, however I acknowledge that others may view it differently and possibly it may work better if drawn as a one way road rather than a roundabout.
To support the roundabout view note that if approaching the roundabout from the SW along Holloway Lane or from the E along Shepiston Lane there are roundabout type signs showing the layout of the junction.
However to support the opposing view
1. Note that signs in the middle of the roundabout consist of a white arrow in a blue circle with a sign underneath saying Dual Carriageway (never noticed that on a roundabout).
2. It is possible (in fact you are directed) to turn right from the roundabout into the centre (ie onto the meat of the hamburger), I don't think we can map a hamburger roundabout to work like that!
3. If approaching from the NW down Cherry Lane there is no sign of a roundabout sign and once on "the roundabout" the road sign treats it more like a cross roads with a turn left for Uxbridge, right for M4 and straight on for everything else.