Pedestrian intervisibility splays at a private driveway

A pedestrian intervisibility splay driveway requirement is the small triangle at the back of the footway that lets a driver leaving your drive see someone walking along it, and lets the pedestrian see the car. Most highway authorities ask for roughly 2 metres by 2 metres on each side of the access, measured from the back of the footway, kept clear of anything above about 0.6 metres in height. It is a different thing from the vehicular visibility splay out onto the carriageway, and it is the one that catches householders, because it falls entirely within the front garden and is usually occupied by a wall.

Check your authority's own standard. The dimensions vary, some authorities specify 2.4 metres, and a few set a different obstruction height.

What the splay protects

The hazard is a reversing or emerging car meeting a pedestrian, a pushchair, a wheelchair user or a child at the point where the drive crosses the footway. Neither party has much time to react, and sight lines at that point are short.

Hence the triangle. Set out from the point where the drive meets the back of the footway, extending along the boundary in each direction and out towards the footway, it defines the area where a solid obstruction would hide one party from the other. A low wall or a flower bed is fine. A 1.8 metre fence running to the edge of the drive is not.

The same geometry is why authorities object to high boundary treatments either side of new accesses even where the vehicular visibility onto the road is perfect. The two tests are separate and both have to be met.

The dimensions usually required

Treat those as the pattern rather than the rule. Published highway design guidance differs between authorities, and the figure that applies is the one in your authority's adopted standard. Ask for it in writing when you ask about the dropped kerb, because the same team deals with both.

Where the footway is wide and the drive is long enough for a car to stop clear of it, some authorities relax the requirement. Where there is no footway at all and the drive meets the carriageway directly, the pedestrian splay is replaced by the vehicular visibility requirement, which is usually more demanding.

Walls, fences and planting

Three practical points decide whether a frontage design will pass.

Height is measured from the footway level, not from your garden level. A 600 millimetre wall on ground raised 300 millimetres above the footway is a 900 millimetre obstruction as far as the highway engineer is concerned, and that is a common reason for a refusal of the crossing.

Planting grows. A hedge planted on the splay line at 500 millimetres will be a metre within three years, and the condition requiring the splay to be kept clear runs with the land. Plant behind the line and leave yourself the maintenance space.

Piers and gate posts count. A pair of brick piers either side of the entrance sits exactly where the splay needs to be clear, which is why the usual design answer is to step the wall down to a low plinth within the splay and raise it again beyond.

Remember the separate permitted development limit on boundary structures: walls, fences and gates next to a highway used by vehicles are limited to one metre in height under Part 2 of the General Permitted Development Order 2015, and two metres elsewhere. A frontage wall above a metre needs planning permission regardless of the visibility question.

Gates that open across the footway

A gate that swings out over the footway obstructs the highway, and highway authorities will not accept it.

The options are to hang the gates to open inwards, to use sliding or folding gates that stay within the boundary, or to set the gates back far enough that an open leaf stays clear of the footway. Set back is the usual answer where the gates must open outwards for practical reasons, and some authorities specify a minimum set back distance for gates serving a drive.

Automated gates add two further points. They need a safe refuge for a driver waiting for them to open, which on a short drive means the car waiting on the carriageway, and authorities dislike that. And the opening sequence has to be considered against the pedestrian splay, because an opening leaf can itself be the obstruction.

Where the footway is narrow

On a narrow footway the geometry gets tighter and the authority gets stricter, because a pedestrian has nowhere to step aside.

Expect a requirement for the drive to be long enough that a vehicle can stop with its front clear of the footway, for the surface to be laid so a driver can see the footway from the stopped position, and sometimes for a larger splay than the standard figure. On very narrow footways some authorities refuse new crossings outright, particularly where there is on-street parking that would block the sight line in any event.

If the frontage is short, be realistic early. A drive that cannot hold a car clear of the footway is not a drive the authority will approve, whatever the splay looks like on paper.

Drawing it correctly

Put it on the same drawing as the access and the dropped kerb, at a scale where the dimensions can be read, usually 1:100 or 1:200.

1. Show the back of footway and the highway boundary as separate lines, because they are frequently not the same.
2. Mark the centre line of the access and the point where it meets the back of footway.
3. Draw the triangle on each side with its dimensions annotated.
4. Show every existing and proposed structure within the triangle, with heights above footway level.
5. Note the proposed boundary treatment heights, inside and outside the splay.
6. Add a section through the frontage if ground levels differ from the footway.

That drawing answers most of the highway officer's questions before they are asked, which is the point. Where the splay forms part of a larger application, the same material sits comfortably in a Transport Statement alongside the vehicular visibility evidence, and a Parking Survey is sometimes requested where the loss of on-street space is in issue.

The consents and the conditions

Three separate permissions can be involved, and they are often confused.

The vehicle crossing over the footway is consented by the highway authority under section 184 of the Highways Act 1980, with the construction specified and usually carried out by an approved contractor at your cost. Planning permission is needed for the access itself only where permitted development rights do not cover it, which includes a new access onto a classified road or trunk road. And the hard surfacing in the front garden has its own permitted development condition about porous materials or directing run-off within the curtilage.

Where planning permission is granted, expect a condition requiring the pedestrian splays to be provided before the access is first used and kept clear of obstruction above the stated height afterwards. That condition runs with the land, so a later owner planting a hedge on the splay is in breach.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. If the driveway forms part of a larger project, browse the report types to see which documents the council is likely to ask for.