When a scheme needs a section 278 or section 38 agreement
Section 278 and section 38 agreements are triggered by the nature of the highway works rather than the number of units. Here is the progression, the technical approval timetable and the costs around it.
The section 278 agreement threshold is not a number of units. It is the moment your scheme needs something built in land the highway authority owns or maintains, and that moment arrives much earlier than most developers plan for. A single dwelling needing a wider vehicle crossing is already interacting with highway legislation. A scheme with an estate road the council will adopt is in a different world again, with two agreements, a technical approval process and a programme that runs alongside the planning application rather than after it.
What changes as the access demand grows
The progression is reasonably predictable and it is worth mapping your scheme against it before you fix a programme.
| Scheme scale | Typical highway requirement | Legal instrument |
|---|---|---|
| One dwelling, existing access | Possibly nothing, or a new or widened vehicle crossing | Section 184 crossing consent |
| Two to four dwellings on a shared private drive | Crossing works, visibility splay clearance, sometimes footway reconstruction | Section 184, occasionally section 278 |
| Five to nine dwellings | Junction improvement, footway widening, tactile crossings | Section 278 agreement |
| Ten or more with a private drive | Larger junction works, drainage connections, possibly traffic calming | Section 278 agreement |
| Ten or more with an adoptable road | All of the above plus the estate road itself | Sections 278 and 38 together |
| Fifty or more | Network-wide works, signals, sustainable transport measures | Sections 278 and 38, plus obligations |
The trigger for a section 278 is the nature of the works, not the size of the scheme. A single house on a classified road with substandard visibility can need one. Forty houses off an existing estate road with an adequate junction may not.
The trigger for a section 38 is different again. It applies where a new street will be offered for adoption as public highway, which is a choice as much as a requirement. A developer can keep the road private and put a management company in place instead, and on small schemes that often costs less once bonds, commuted sums and the adoptable specification are counted.
Works in the existing highway
A section 278 agreement is the mechanism by which a private party pays for and carries out works to the public highway. It is a contract, and its terms cover the works, the standard, the timing, the security, the fees and the authority's remedies.
Three things that surprise first-time developers.
The authority decides the specification, not you. Materials, lighting levels, drainage detail and construction depths follow the authority's own standards, which are usually more demanding than a private estate specification.
The works have to be designed to an approved standard and then audited. Road safety audits are carried out at defined stages by a team independent of the designer, and audit recommendations either get implemented or get formally rejected with reasons. A road safety audit is not a document PlanScope generates and it needs an independent auditor with the specified training.
And the agreement is with the highway authority, which on a two-tier arrangement may be the county council while the planning authority is the district. Two organisations, two timetables, and no obligation on either to coordinate with the other.
Adoption of new roads
A section 38 agreement commits the authority to adopt a new street once it is built and maintained to standard for a period. It brings an adoptable specification, technical approval, inspection during construction, a maintenance period and security for the works.
The specification is the part with cost in it. Adoptable roads need particular construction depths, adopted street lighting with a maintained supply, highway drainage designed to the authority's standard with its own outfall arrangements, and street furniture from an approved range. A scheme that has been designed to a private standard and then offered for adoption usually needs redesigning.
Sustainable drainage adds a complication. Where surface water from an adoptable road discharges to features the highway authority will not maintain, someone has to. That is where commuted sums appear, and they are a permanent cost rather than returnable security. The relationship between access arrangements and the internal layout at different scheme sizes is covered in from a single access to an internal road network.
Technical approval and its timetable
Technical approval is the process by which the authority checks and approves the detailed design. It is separate from planning permission, it starts after outline design, and it runs in stages.
- Pre-application discussion with the highway development management team about principle and standards.
- Agreement of the scope of works and any departures from standard.
- Stage 1 road safety audit on the preliminary design, with the designer's response.
- Detailed design submission, including drainage calculations, lighting design, construction details and a signing and lining plan.
- Stage 2 road safety audit on the detailed design.
- Technical approval issued, agreement executed, security in place.
- Construction, inspection, stage 3 audit after completion.
Each stage takes weeks and several of them depend on a third party. Departures from standard need separate approval and are the single most common cause of delay, because a departure that looks minor to a designer looks like a liability to an authority.
Budget six months from first submission to executed agreement on a straightforward scheme and treat anything faster as a bonus. Start the conversation during the planning application rather than after the decision.
Sequencing against the planning condition
Planning permission and highway agreement are separate processes joined by a condition. The condition wording determines your programme, so read it before the decision issues.
A condition requiring works to be completed before first occupation is manageable. It lets you build houses while the junction is designed and constructed, and it only bites at the end.
A condition requiring that no development take place until the section 278 agreement has been entered into is far more restrictive. It puts a third party's legal timetable on your critical path before you can start anything, including site clearance.
A condition requiring works to be completed before any development starts is the worst case and should be resisted at the application stage with reasons, because it forces you to build a junction serving an empty field.
Where the works are needed to make the development acceptable, a Grampian condition is legitimate and you will not get rid of it. What you can influence is the trigger point. Argue for occupation rather than commencement where the highway concern relates to residents rather than construction traffic, and deal with construction access separately in a Construction Traffic Management Plan.
Budgeting the whole package
The works themselves are rarely the largest surprise. The surrounding costs are.
Design fees for the highway works, which are engineering fees rather than planning fees. Technical approval and checking fees charged by the authority. Legal fees for both sides, with yours paying theirs. Inspection and supervision fees during construction, commonly a percentage of the works value. Road safety audit fees at each stage. Traffic management and road space booking costs, which on a classified road with night working can rival the construction cost. Security in the form of a bond premium or a cash deposit. And commuted sums where the authority will maintain something non-standard.
Assemble the list early and price it from the authority's published fee schedule rather than from an assumption. Where a Transport Assessment is being prepared for the application anyway, the same engineer can usually give you an order of cost for the highway package at the same time, and a Transport Assessment that has been written with the eventual agreement in mind avoids proposing mitigation that turns out to be undeliverable.
The pattern to avoid is the one where the planning permission is granted, the appraisal assumed a modest access cost, and the technical approval process then produces a specification nobody priced. Enter your postcode on PlanScope to see which transport and construction documents the application itself will need.
This is general guidance, not legal advice; check the position with your local 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.
Frequently asked questions
At how many units does a section 278 agreement become necessary?
There is no unit threshold. The trigger is whether the scheme requires works in land the highway authority owns or maintains. A single house on a classified road with substandard visibility can need one, while forty houses off an existing estate road with an adequate junction may not. Ask the highway authority early.
Do I have to offer a new estate road for adoption?
No. Adoption under section 38 is a choice. A developer can keep the road private and put a management company in place instead, which on small schemes often costs less once the adoptable specification, bond and commuted sums are counted. Purchasers and lenders will ask about the arrangement, so decide early and disclose it.
How long does technical approval take?
Budget around six months from first submission to an executed agreement on a straightforward scheme, and treat anything quicker as a bonus. The process runs through scoping, road safety audits at defined stages, detailed design submission and approval of any departures from standard. Departures are the commonest cause of delay.
Can the scheme designer do the road safety audit?
No. Audits are carried out at defined stages by a team independent of the design team, holding the training and experience the relevant design standard specifies. Audit recommendations must either be implemented or formally rejected with reasons. PlanScope does not generate road safety audits, so budget for an independent auditor.
Which condition wording should I argue for?
Completion of highway works before first occupation, rather than before commencement. An occupation trigger lets you build while the junction is designed and constructed. A condition preventing any development until the agreement is executed puts a third party's legal timetable on your critical path before site clearance can start.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.