Visibility splays are drawn on plans as two neat triangles. The question officers ask is simple: can the land inside them be kept clear for the life of the development? If not, the access may not be acceptable however good the design.
Why control matters
A splay only works if nothing grows or is built in it. The council can secure that with a condition when the land is within the site or is public highway. When it crosses a neighbour’s garden or a field the applicant does not own, there is usually no way to make sure it stays clear.
Where the highway really ends
The public highway often includes the verge, and sometimes the hedge line, not just the tarmac. But not always. The only way to know is a highway boundary search, sometimes called a highway extent plan, from the highway authority. Many councils charge for it and it can take a few weeks, so ask early.
Ransom strips
Sometimes a narrow strip of land between the site and the highway belongs to someone else. Whoever owns it can control access to the site, and may ask for payment. A highway boundary search, alongside the title plans, shows whether there is a gap. Ownership and rights are legal questions for your solicitor, but spotting the gap is a transport planning job.
What you can do
- Measure the speeds. If traffic is slower than the limit, the splay can often be shorter and may avoid the problem land.
- Move the access. A different position along the frontage can change everything.
- Agree with the neighbour. A legal agreement to keep land clear is sometimes possible.
- Use highway land. Cutting back a hedge within the highway verge may be acceptable to the council.
Buying a site? A highway boundary search is one of the cheapest checks you can do. Get the guide.
General information, not advice on a specific site. Policy and guidance correct as of October 2026.