National Highways consultation on the strategic road network

A national highways planning consultation is triggered when development is likely to affect the strategic road network, the motorways and trunk roads that National Highways operates in England. The council must consult, and National Highways can do something a local highway authority cannot: issue a direction that stops the council granting permission while it considers its position.

That power is why developers treat its response differently from a highways officer's memo. The consultation itself is ordinary. The direction is not.

When it is consulted and on what

National Highways is a statutory consultee under Schedule 4 to the Development Management Procedure Order 2015 for development that would affect trunk roads and motorways. In practice councils consult where a site takes access from the network, sits close to a junction with it, or generates traffic that will use a junction already under pressure.

Its interest is narrower than a local highway authority's. The local authority looks at the site access, the internal layout, parking, servicing and the local network. National Highways looks at the safety and operation of its own asset, which usually means one or two junctions, the merge and diverge arrangements, and anything that would put traffic on the hard shoulder or a slip road.

Two things it will not do. It does not act as a second opinion on your site layout. And it does not consider whether the development is a good idea in planning terms, which is the council's job.

The consultation also reaches beyond individual applications. National Highways comments on emerging local plans and site allocations, and an allocation that was accepted at examination without objection is a much easier starting point than one the body resisted. Check what it said about your site at plan stage before you assume the position is open.

The policy framework applied to trunk road impacts

Department for Transport Circular 01/2022 sets out the approach National Highways takes to development affecting the strategic road network. It frames the network as an asset for long-distance and freight movement, expects development to be planned so that it does not rely on the network for short local trips, and looks for genuine alternatives to car travel before it looks for junction capacity.

National policy has for years framed highways refusals around two tests: an unacceptable impact on highway safety, or residual cumulative impacts on the road network that would be severe. Verify the exact wording and the policy code in the current National Planning Policy Framework before you quote it, because the Framework was re-issued on 17 August 2026 with policy-coded chapters replacing paragraph numbers.

The practical consequence for a developer is that a scheme with weak sustainable transport credentials attracts a longer and more sceptical response, even where the modelling shows the junction copes. A Travel Plan with real measures, monitoring and a funded coordinator carries more weight in that conversation than another year of modelling.

Holding directions and the timetable

Where National Highways wants more time or more information, it can ask the Secretary of State's direction-making power to be used, and a direction restricting the grant of permission is issued to the council. The instrument is the Town and Country Planning (Development Affecting Trunk Roads) Direction 2018.

While a direction is in force the authority cannot grant permission. It can still refuse. That asymmetry matters, because a council under pressure on its performance figures may refuse rather than sit under a direction, leaving the applicant with an appeal instead of a negotiation.

Directions are usually lifted once the information National Highways asked for arrives and is accepted. The way to avoid one is to make sure the transport evidence answers the questions before the consultation response is written, and to talk to the National Highways planning team while the assessment method is still open.

Plan for the timetable effect. A direction plus a round of modelling revisions plus re-consultation adds months, not weeks, and the determination period will need an extension of time to survive it.

The junction capacity evidence expected

Scope the work with National Highways rather than presenting it. The items that get disputed are almost always inputs rather than outputs.

1. Assessment years, including the opening year and a future year, with growth applied from an agreed source.
2. Trip generation, normally from the TRICS database, with the site categories, filters and date ranges stated so the selection can be reproduced.
3. Trip distribution and assignment, evidenced rather than assumed, with the method for assigning trips to the network set out.
4. Committed development, agreed as a list with a stated cut-off date, and checked against the base traffic surveys so trips are not counted twice.
5. Junction modelling using the appropriate software for the junction type, with model files and audit information supplied.
6. Safety analysis using collision data for an agreed study area and period.

Where a scheme is large enough to need a Transport Assessment, the strategic road network work sits inside it as a distinct section with its own agreed scope. Smaller schemes near a trunk road junction may only need a Transport Statement, and asking early avoids paying for modelling nobody wanted.

Any physical design work on the network follows the Design Manual for Roads and Bridges, and departures from standard need formal approval, which takes time and is not in the applicant's gift.

Mitigation, contributions and delivery

Mitigation on the strategic road network is delivered under an agreement with National Highways rather than with the council, and the design, technical approval and construction of works on the network follow its own processes.

Three practical points. Physical works take far longer to design and approve than the planning application that requires them, so the trigger in any condition or obligation has to be realistic. A financial contribution towards a scheme already programmed is easier to agree than a bespoke junction improvement. And a contribution has to meet the statutory tests for planning obligations, so it needs to be necessary, directly related to the development and fairly related in scale.

Where mitigation cannot be delivered, the honest options are to reduce the quantum of development, to phase it against network improvements, or to argue that the residual impact is not severe. The third of those is a policy argument and it needs the evidence base to support it.

Engaging before submission

The single most useful thing on a site near the strategic road network is a pre-application conversation with the National Highways planning team, held before the transport consultant has modelled anything.

Ask three questions. Which junctions do you want assessed, and to which years? What growth factors and committed development list do you expect? And is there a programmed improvement scheme in this corridor that our contribution could sensibly go towards?

Agreeing those in writing turns the later consultation response into a check rather than a negotiation. It also gives the case officer something to rely on, which is usually the difference between a conditioned approval and a delayed one.

Enter your site postcode on PlanScope to see which transport and highways documents your scheme is likely to need before you commission the modelling.

This is general guidance and not legal advice. Check the position with your local planning authority, the relevant highway authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.