Most highways objections never get close to the test national policy sets for refusing permission. Knowing where that line sits changes how you respond.
The test
The National Planning Policy Framework was updated in August 2026. Policy TR6(4) says development should be refused if it would have a severe adverse impact on the transport network, including cumulative impacts, or an unacceptable impact on highway safety. Mitigation and planned improvements to the wider network are taken into account, and the test applies during construction as well as once the scheme is built.
The word “severe” first appeared in the 2012 Framework. The wording around it has changed over the years, but the principle has not: there are two tests, and the bar for both is high.
Two tests, not one
Highway safety asks whether the scheme creates an unacceptable risk. A substandard access, poor visibility or people forced to walk in the road can all fail it. A collision record nearby matters if the scheme would make it worse.
The network test asks whether the effect on traffic is severe once mitigation is allowed for. More vehicles, longer queues or a junction close to its capacity are not, on their own, severe.
What usually falls short of severe
Neither the Framework nor national guidance defines severe. Inspectors decide it case by case, on the evidence, and appeal decisions have consistently treated it as a high bar. These rarely meet it:
- A few extra vehicles in the peak hour at a junction that works today
- A junction near capacity where the scheme adds very little
- Slightly longer queues that still clear
- General concern about traffic, without evidence about specific junctions
What can tip it
- A junction already over capacity, where the scheme adds noticeably to queues
- Queues that block back through other junctions, a level crossing or a trunk road
- Several committed schemes adding up at the same junction
- Safety problems that no reasonable mitigation can fix
A recent reminder from the courts
In Greystoke CB Ltd v Secretary of State [2026] EWHC 1997 (Admin), the High Court found an inspector had erred. The inspector decided the highways threshold was not met, then still gave the traffic effects substantial weight against the scheme without returning to the policy test. The case was decided under the previous wording of the Framework, but the point carries over: where traffic is the main reason against a scheme, the decision-maker has to engage properly with the test.
How to respond to a “severe” objection
- Ask which junctions and which hours the concern relates to.
- Check the trip rates and traffic growth assumptions against recognised data.
- Model the junction properly if it is genuinely in question.
- Separate existing problems from the effect of your scheme.
- Offer proportionate mitigation where it is actually needed.
Most of the time, a clear technical note answers the concern before it reaches committee or appeal.
General information, not advice on a specific site. Policy and guidance correct as of October 2026.