The alternative of course is to improve visibity from the slip road, noting that a slip road typically starts around 6-8m above or below roundabout level.

This means that some aspects may need to be re-engineered:

• if roundabout is below motorway, the raised carriageway will obscure a vehicle on the roundabout. One option would be to re-engineer the carriageway to elevate it on slim supports allowing a full view of the roundabout as you motor down the slip road
• if roundabout is above the motorway we could lengthen the slip road so that for the final (say) 100m the slip road is level with or slightly above the roundabout thus improving visibility

Alternatively we could instal traffic light as already exists on many junctions althogh this also has the potential to slow down traffic.

Or perhaps some large red/green indicator lights visible from the slip road to indicate whether there are other vehicles on the roundabout (feasible but complex)

Other than the traffic light solution you would then be able to surge up the slip road, and go right or left at full bore on opposite lock if you so chose in complete safety!

In a similar vein, it cannot be coincidence that bus stops are installed in line with traffic islands can it? (''disrupt traffic flow at all costs'')

Just to make roundabouts on dual carriageways much safer, not, they've taken to erecting fencing between the carriageways on the approaches, ensuring helpfully that you can't see if the roundabout is clear to aid normal progress.

That may be a bit cynical, GB. The fencing may be there to limit blinding by over-bright headlights raking every driver as they leave the roundabout. Pluses and minuses ?

But I agree that some roundabouts have very limited visibility often caused by excessive shrubbery in the centre or the approaches.

Northamptonshire alone has many fine examples of this planning mentality, helping bring the county traffic ever closer to the grinding halt it's heading for.

Like this one on Danes Camp Way?

goo.gl/maps/iffCJmKWjkj1ArJ48 ?

It's there because traffic coming up from M1/J15A was just steaming onto the roundabout endangering both traffic already on it and folks trying to join from the housing etc at Briar Hill.

It may be a PITA but there's a clear rationale.

Many roundabout now have, as an option to fencing, significant amounts of bushes and/or trees that completely block the view of oncoming traffic to what's on the roundabout. I suspect that the planners' reasoning is that this will help stop people who don't or barely slow down at roundabouts.

The trouble is, most of these people who do that still do. Given they cannot see anything, they are likely to not slow down at all because they see a vehicle.