Highway technical approval and who may design the works

Highway technical approval competence is a separate question from planning permission, and it catches developers out because the two processes run on different clocks and answer to different people. A planning permission can require an access to be built. It does not authorise anyone to build it, and it says nothing about whether the design is acceptable to the body that will inherit the road.

Works in the existing highway are carried out under an agreement made with the highway authority under section 278 of the Highways Act 1980. New streets intended for adoption go through section 38. In both cases the design has to pass technical approval before anyone puts a cone out.

What technical approval is and who grants it

Technical approval is the highway authority's assurance process for design. It exists so that whoever ends up maintaining the asset, usually the authority itself for the next century, is satisfied the design meets the standards it will be judged against.

The authority acts as the technical approval authority, and that role is held by a named team rather than by the development management planners. For the strategic road network the authority is National Highways. For most development it is the county council, unitary authority or Transport for London, each with its own published procedure. The process is modelled on the framework used for highway structures in the national design standards, which requires an approval in principle document to be agreed before detailed design begins.

The sequence is consistent even where the paperwork differs. Agree the principle, agree the standards and departures, then submit detailed design for approval, then build under inspection.

Designer competence and the approval in principle

The approval in principle document sets out what is being designed, the standards being applied, the loading and design assumptions, the intended maintenance regime, and any departures from standard being sought. It is signed by the designer and countersigned by the authority.

Designer competence is tested at this point. What the authority looks for is a chartered engineer in the relevant discipline, professional indemnity insurance at the level the agreement requires, and demonstrable experience of comparable works on a public highway. For structures the expectation is a chartered civil or structural engineer, and for geotechnical elements such as retaining walls the competence framework under Eurocode 7 applies alongside the highway standards.

Departures from standard are the part to raise early. A visibility splay short of the standard for the road's speed, a gradient outside the normal range, or a substandard forward visibility at a bend all need a departure, and departures are granted by the authority rather than assumed by the designer. A planning application that shows a substandard geometry without a departure already agreed is building a problem into the permission.

Structures, drainage and lighting within a highway scheme

Each discipline has its own approval route within the same agreement, and they rarely progress at the same speed.

Drainage is the common cause of delay. A highway drain discharging to a watercourse needs a consent from the lead local flood authority or the Environment Agency depending on the receiving water, and a soakaway in the highway needs infiltration evidence the authority accepts. Where sustainable drainage features sit in the adopted highway, the authority will ask who maintains them and how, and a vague answer stops the approval.

Lighting brings a cost few schemes budget. Many authorities require a commuted sum covering maintenance and energy for a defined period, calculated from the column count and specification.

Checking categories and independent checks

Highway structures are assigned a category of check based on their complexity and the consequences of failure. Lower categories allow the design to be checked within the designer's own organisation, by someone independent of the design team. The highest category requires the check to be carried out by a separate organisation with no commercial connection to the designer.

Budget and programme for that independent check from the outset. It is not a formality, it produces comments that change the design, and appointing the checker late is a reliable way to lose six weeks. The check certificate is a deliverable the authority will not proceed without.

Road safety audit sits alongside this rather than inside it. Audits are carried out at defined stages by an audit team independent of the designer, and the audit brief, the audit report and the designer's response all form part of the approval record. A road safety audit is a specialist output prepared by an independent audit team, and it is not one of the reports PlanScope produces.

Where a designer must be on an approved list

Some authorities maintain lists of designers, checkers and contractors accepted for works on their network, and some restrict certain activities to their own term maintenance contractor. Street works on the highway also require operatives and supervisors holding the accreditation required by street works legislation.

Ask three questions at the first meeting. Does the authority require the designer to be on a list or otherwise accepted. Can the developer appoint its own contractor or must the authority's term contractor carry out the works. And who provides the independent checker where one is needed. The answers change the procurement route and the cost, and they are rarely written down anywhere you can find without asking.

Programme effect of an approval cycle

The realistic programme is longer than most development appraisals assume, because approval is iterative.

1. Pre-application discussion with the highways team, separate from the planning pre-application.
2. Approval in principle submitted, commented on, revised and agreed.
3. Detailed design submitted, commented on, revised and approved.
4. Independent check where the category requires it, with design amendments in response.
5. Section 278 or section 38 agreement drafted, bond and fees agreed, legal completion.
6. Works, inspected in stages, followed by a maintenance period before adoption.

Each of those steps involves a comment cycle measured in weeks rather than days. A scheme that assumes access works can start the week after planning permission is granted has misunderstood the process. Start the highways conversation while the Transport Assessment is being prepared, since the access design in that document is the one you will be approving later.

Coordinating approval with the planning condition

Planning conditions and highway agreements have to be drafted to fit each other. The usual mechanism is a condition preventing occupation, or sometimes commencement above slab level, until the access works have been completed in accordance with a scheme approved by the local planning authority in consultation with the highway authority.

Two drafting points save arguments later. Tie the trigger to a stage the developer controls, because a condition preventing commencement until an off-site junction is complete can stall a site for a year. And make sure the condition refers to the same drawing numbers as the agreement, since a condition approving one layout while the agreement approves another is a breach waiting to be noticed.

Construction access is a separate strand again, usually controlled through a Construction Traffic Management Plan condition and a temporary works approval from the authority.

One honest uncertainty: the scope of what a local highway authority will require by way of technical approval varies considerably between authorities, and the distinction between a simple dropped kerb and a scheme needing a full approval in principle is a matter of local practice. Ask the authority in writing what it requires for your scheme, and understand what competent person means in planning legislation before you appoint. Reviewers and specialists can be found through the professional directory.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. For specialist technical reports, qualified professional input may be required.