Visibility Splays

gravel driveway to custom home
(Image credit: getty images)

The last thing you would want to do when driving out of your new home is to have to enter a road without being able to see what’s coming in both directions. It’s dangerous, and that’s why the authorities will insist that any new entrance onto a trunk or classified road has a visibility splay — which, even in a 30mph limit will usually mean a requirement to have a clear view of 70m (metres) in each direction.

A visibility splay is formed by measuring to a point 2.4m back from the carriageway in the centre of the driveway or entrance. A line (70m long in the case of a 30mph limit) is then drawn to the right, to a point where it strikes the near-side edge of the carriageway. Another 70m line is then drawn to the left, to a point where it strikes the opposite edge of the carriageway. Any land that is contained within the unequal triangle that is thus formed on the entrance side of the carriageway, must be kept clear, in perpetuity, of any obstruction above 1.005m. If you think about it, the distance back allows for the bonnet length and the height is one’s eye height when sitting in the driver’s seat.

David Snell

David is one of the UK's leading self build and plotfinding experts, and a serial self builder who has been building homes for 50 years. The author of Building Your Own Home, David spent decades as a speaker and expert at self build exhibitions such as the Homebuilding & Renovating Show. He has recently finished his fourteenth self build project.