Checklist: what a highway authority wants with a new access

The new access highway authority requirements come down to one proposition the officer has to be able to sign off: a driver leaving your site can see far enough along the road, and be seen, to pull out safely at the speed traffic actually travels. Everything else on the checklist supports that. Get the speed survey and the visibility splay drawing right and most highway objections disappear. Submit a site plan with a splay triangle drawn by eye and you will get a holding objection, then a four week delay while you commission the survey you should have started with.

Establishing the design speed of the road

The splay geometry is derived from speed, and the relevant speed is what vehicles do rather than what the sign says. A 30mph limit on a straight suburban road with wide verges may carry an 85th percentile speed well above the limit, and the required visibility grows with it.

So commission an automatic traffic count over seven continuous days, giving the 85th percentile wet weather speed in each direction at the access location. Choose a neutral period: avoid school holidays, the fortnight either side of Christmas, and any week when roadworks are affecting the route.

Where the road is lightly trafficked and a survey would produce too small a sample, radar spot speeds taken over a representative period are sometimes accepted, but ask the highway officer first and record the answer. On a 60mph national speed limit rural lane with poor alignment, the measured speed is often well below the limit, and the survey works in your favour.

Get the survey in before the design is fixed. A splay requirement that arrives after the house has been positioned is the most expensive sequence there is.

Visibility splay drawing requirements

Visibility is expressed as two dimensions. The X distance is measured back from the edge of the carriageway to the driver's eye position within the site, commonly 2.4m, with a shorter figure sometimes accepted on a slow-speed residential street. The Y distance is measured along the carriageway in each direction and is derived from the stopping sight distance for the measured speed, using Manual for Streets for lower-speed streets and the Design Manual for Roads and Bridges for higher-speed roads.

The drawing has to show, at a stated scale:

1. The X and Y dimensions annotated, with the design speed and its source stated on the drawing.
2. The splay triangles plotted in both directions, measured to the nearside carriageway edge, following the curvature of the road rather than as a straight chord.
3. The driver's eye height and the object height used, taken from the relevant guidance.
4. Everything within the splay that could obstruct it: walls, fences, hedges, gate piers, bin stores, parked vehicles, street furniture and signs.
5. The land within the splay shown as being within the applicant's control or within the publicly maintainable highway, with ownership shown by a colour or hatch.
6. The highway boundary as recorded by the highway authority, not the title plan boundary.

That sixth point is where applications fail quietly. If the splay crosses land you do not own and cannot control, it is not deliverable, and a condition requiring it to be provided and maintained cannot be complied with. Find out early, because the answer may be a different access position.

Hedges inside a splay need a maintenance commitment. A condition requiring vegetation within the splay to be kept below 900mm in height is standard, and it binds your successors.

Access width, gradient and surfacing details

Authorities publish their own standards and they vary, so treat the following as the common pattern and check the local design guide.

Access width for a single dwelling is commonly 3m at the minimum, widening to 4.1m or more where two vehicles need to pass, and 5m where the access serves several dwellings. The bellmouth radii at the junction with the highway are specified separately.

Gradient matters more than people expect. The first few metres from the carriageway edge are usually required to be near level, often no steeper than 1 in 20, before any steeper section begins, so that a vehicle waiting to emerge sits level and the driver's eye height is as assumed in the splay calculation. A steep first 5m also drags surface water and grit onto the road.

Surfacing follows from that. The first 5m or 6m inside the site is normally required to be bound, in bitumen macadam, concrete or block paving on a proper base, to stop loose gravel migrating onto the carriageway. Show the construction build-up in a detail, and show the long section with levels at the carriageway edge, at the site boundary and at the parking area.

Gates, where proposed, need a set-back so a vehicle can stand clear of the carriageway while they open, and they must not swing over the highway.

Drainage so water does not run to the highway

Highway authorities are consistent on this, and it is the condition applicants most often overlook until the officer raises it. No surface water from the site may discharge onto the highway.

Three elements satisfy it. A linear channel or slot drain across the access at or near the highway boundary, with its invert level shown. A positive outfall from that channel to a soakaway, a watercourse or a surface water sewer, with the route drawn. And infiltration test results supporting the soakaway design where infiltration is the method, with the soakaway sized using an accepted method and positioned at the required distance from buildings and boundaries.

Add the existing highway drainage to the drawing, because an access built across a highway ditch or over a gully needs a piped crossing or a relocated gully, and that is highway works rather than site works. Those details are the sort of thing that comes back at condition discharge stage, which is easier when the submission is organised, as our checklist for a submission discharging a drainage condition sets out.

Parking and turning within the site

The highway officer assesses parking as a highway safety matter rather than as an amenity one. Insufficient on-plot parking means vehicles on the carriageway near a new access.

Show the parking spaces dimensioned to the local standard, with the manoeuvring space in front of each and the aisle width where spaces are in tandem. Tandem spaces are often counted as one and a half rather than two, so check how the authority treats them.

Turning within the site is required wherever a vehicle should not reverse onto the highway, which usually means any classified road and often any road with a 30mph limit or above. Prove it with vehicle tracking rather than a note: a swept path drawing for a standard car entering, turning and leaving in forward gear, and a second one for a refuse vehicle where it has to enter the site.

Cycle parking and, increasingly, electric vehicle charging provision appear on the same drawing. Charge point provision for new dwellings comes through the Building Regulations rather than from the highway authority, but showing it avoids a later clash with the parking layout.

Section 184 and section 278 processes

Planning permission does not authorise work in the highway. Two separate Highways Act 1980 processes do.

Section 184 covers a vehicle crossing over a footway or verge, which is the dropped kerb or crossover application. You serve notice on the highway authority, which may specify the works and the materials, and the construction is carried out by or on behalf of the authority at your expense. Lead times vary and a crossover is not something to leave to the week before completion.

Section 278 is an agreement for more substantial works to the existing highway: a new junction, carriageway widening, a footway diversion, visibility works requiring the removal of highway vegetation, or a new passing bay. It involves technical approval of the design, a bond or cash surety, inspection and commuted sums, and on larger schemes a road safety audit. Budget months rather than weeks.

Section 38 applies where a new street is to be adopted, which is relevant only to multi-plot schemes. For a single self-build, section 184 is usually the whole story, with section 278 where the splay needs highway land cleared.

Information that speeds the response

Highway consultation responses are slow when the officer has to ask for things. Submit these together and the response is usually quick:

• a dedicated access drawing at 1:200 or 1:500 showing splays, widths, radii, gates and surfacing
• a long section with levels at the carriageway edge, the boundary and the parking area
• the speed survey with its dates and methodology
• swept path drawings for a car and a refuse vehicle
• a drainage detail at the access
• a photograph sheet showing the existing access and the view in each direction from the driver's eye position
• confirmation of ownership or control of all splay land

Speak to the highway officer before you submit. A ten minute call about the access position, recorded in a note, will tell you whether the scheme works, and that is worth more than any amount of drawing. A short Planning Statement should summarise the access case and cross-refer to the drawings, and a Transport Statement is only needed where the scale of development warrants it. Consistent drawing numbering across the set avoids a validation query, as covered in drawing schedules and title blocks that survive validation.

This is general guidance, not legal advice. Check the position with your local planning 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.