A visibility splay is a drawing plan than visualises the angle and distance from which drivers drivers emerging from an access can see and be seen by drivers proceeding along the priority road. it ensures that any buildings works for entrances and exits have good visibility to prevent motor accidents.
Visibility splays are formed in the following way:
- measure 2.4 metres from the carriageway in the centre of the entrance or driveway
- draw lines to the left and right until they reach the opposite end of the carriageway
- length of the lines will be proportionate to the speed limit for the zone - in a 30mph zone, for example, the line will need to be around 43m - longer for higher speed limits
- any space within the resulting two triangle areas must remain free of any obstruction above 1.005 metres in your plans.
- road curvature may require that the lines in each direction are of different lengths.
- visibility splays can be included as part of a site layout plan or as their own separate plan
- they should always be drawn to a recognised scale such as 1:200 or 1:500
- they will need to be shaded and state key distances, such as
- the distance from the carriageway in the centre of the entrance or driveway
- the height and the distance of the splays in both directions.