Visibility Splays and New Access: Getting Highways Approval for Your Plot

A new or altered vehicular access is one of the most common sticking points on rural and edge-of-settlement planning applications. The county highways authority is consulted on almost every application that creates one, and a highways objection is enough to ground an otherwise sound scheme.

At the heart of most highways objections is one issue: visibility splays. If drivers pulling out of your access cannot see far enough along the road, and be seen, the access is unsafe.

This guide explains what visibility splays are, how they are assessed, and how to get a new access approved. It is written for landowners, self-builders, developers and the architects supporting them.

What is a visibility splay?

A visibility splay is the triangle of clear sight a driver needs when pulling out of an access onto a road. It is defined by two measurements:

• The X distance: how far back from the road edge the driver’s eye is assumed to be, typically 2.4 metres
• The Y distance: how far along the road the driver must be able to see in each direction

The Y distance depends on the speed of traffic on the road. As a guide, Manual for Streets indicates around 43 metres of visibility for a 30 mph road, rising steeply for faster roads. On rural lanes, actual measured vehicle speeds often matter more than the posted limit, and a speed survey is sometimes needed.

The splay must be kept clear of obstructions above a low height, which is why hedges, banks and walls are so often the issue on rural plots.

Why highways approval matters

The local planning authority decides the application, but the county highways authority (in two-tier areas) or the council’s own highways team advises on safety. Their recommendation carries significant weight.

A highways objection typically leads to refusal. Conversely, early agreement with the highways officer, before the application is submitted, removes one of the biggest risks from your scheme.

What you need to submit

A planning application involving a new or altered access should include:

• An access plan: scaled drawing showing the access position, geometry, surfacing and the visibility splays in both directions
• Evidence the splays are achievable: within land you control or highway land, now and in the future
• Supporting explanation: traffic speeds, expected vehicle movements, and any swept path analysis for larger vehicles
• Construction details: gradients, drainage and gates set back from the carriageway

Access drainage is easy to overlook. Highways authorities will not accept surface water running from your access onto the public road, so the access design and the site’s drainage design need to work together.

How consultation with the highways authority works

On a recent Mid Devon project involving two rural new builds, a new access was agreed through direct consultation with county highways before the application was determined. The agreed visibility splays were shown on an access plan with a supporting explanation, submitted as part of the full application. The permission for two dwellings, access and associated works followed. Read more in our rural new builds case study.

That sequence is the model to follow:

1. Assess the road: speeds, alignment, existing accesses and accident history.
2. Establish what splays are required and whether they can be achieved.
3. Engage the highways officer early with a draft access plan.
4. Adjust the design to their feedback before the application is submitted.
5. Submit the agreed plan and explanation with the application.

Common problems and how to solve them

• The splay crosses third-party land. You cannot rely on visibility over land you do not control. Options include repositioning the access, acquiring rights, or demonstrating the land is highway verge.
• Hedgerows block visibility. Setting a hedge back and maintaining it at low height within the splay is often acceptable, but removal of important hedgerows can raise ecological and landscape issues.
• Fast rural roads. Where measured speeds are high, a speed survey may justify shorter splays than the default values, or the access may need to move.
• Gradients and gates. Steep accesses and gates opening onto the road are routine objections, and both are solvable at design stage.

Conclusion

Visibility splays are usually the deciding factor for a new access, and they are measurable long before you apply. Establish what the highways authority needs, prove it is achievable on an access plan, and agree it with them early.

Handled that way, access becomes a solved problem in your application rather than the reason it fails.

FPS Environmental provides development access design alongside drainage design and land development engineering, so access, levels and drainage are designed together.