How to Draw Visibility Splays on Plans – A Guide for Architects and Planners.

A well-prepared planning application leaves no room for errors, especially when it comes to the details like highway visibility splays. Getting these splays right the first time can:


– Boost your credibility with Planners, Highways Officers, and Clients

– Eliminate the need for costly revisions

– Allow for proactive client communication, increasing satisfaction


By mastering this one aspect, you not only enhance road safety but also increase the likelihood of your application’s success.


 What Exactly Is a Visibility Splay?


A visibility splay is a triangular area formed at road junctions where drivers need an unobstructed view of both directions of the road. It’s a critical safety feature that helps drivers enter or cross roads without endangering themselves or others.


 The Importance of Visibility Splays in Planning Applications


Failing to implement proper visibility splays can lead to delays and rejections of your planning applications. These areas are scrutinized by the Highways Authority to ensure that new developments do not compromise road safety.


 UK Guidelines on Visibility Splays


In the UK, you’ll find the guidelines for visibility splays in the Manual for Streets or the Design Manual for Roads and Bridges. The choice of manual depends on the road’s classification, speed limit, and governing body.


 How to Draw a Visibility Splay


To create a visibility splay for a typical residential 30mph Local Authority road:


  1. Start at the Junction: The access point where your development meets the road.
  2. Measure into the Site: Known as the ‘X’ distance, this is usually 2.4m back from the edge of the carriageway.
  3. Measure Along the Road: For a 30mph road, this is generally 43m.
  4. Mark Obstructions: Clearly indicate any existing obstructions in the splay area.
  5. Check for Compliance: Make sure there are no obstructions higher than 0.6m in the splay area and that the land is either under your client’s control or adopted highway.



Understanding and accurately implementing visibility splays is crucial for both road safety and the success of your planning application. While this guide can’t cover all scenarios, it offers a strong foundation that will help you get it right the first time. Because in planning and architecture, a safe exit is the best start!