Site access gradients and the level landing

A vehicular access needs a flat piece of ground where it meets the public highway, and a controlled slope beyond it. Highway authorities call that flat piece the level landing, and refusing to provide one is a common reason for a highways objection on a sloping plot. The dimensions are set locally, so the figure that matters is the one in your highway authority's design guide, not a number lifted from a forum.

The principle behind it is straightforward. A driver waiting to pull out has to be stationary, level, and able to see along the footway in both directions before any part of the car crosses it.

Why gradient is treated as a safety matter

Three things go wrong on a steep access. Braking distance increases on a downgrade, so a vehicle rolling towards the highway needs more room to stop than the same vehicle on the flat. Sight lines shift, because a driver sitting nose-up on a rising drive looks over the footway rather than along it, and a child on a bicycle disappears under the bonnet line. And the vehicle itself moves differently, with a long wheelbase grounding on a sharp change of grade and a rear overhang swinging as the car pitches.

None of this is unique to new-build plots. It shows up on infill sites, on garden land where the original house sits well above the road, and on any conversion that turns a garden into a parking court.

Whether the access needs planning permission at all is a separate question. Class B of Part 2 of Schedule 2 to the Town and Country Planning (General Permitted Development) (England) Order 2015 permits the formation of a means of access to a highway that is neither a trunk road nor a classified road, where the access is required in connection with development permitted by another class. A new access onto a classified road needs an application. A dropped kerb across the footway also needs separate consent from the highway authority under section 184 of the Highways Act 1980, whatever the planning position is. A Lawful Development Certificate is the only formal way to confirm that works are lawful.

The level landing at the back of the footway

The landing sits between the rear edge of the footway, or the carriageway edge where there is no footway, and the start of the drive proper. Its job is to hold a stationary car level while the driver checks the footway.

Most highway authority design guides ask for the first length of the access to be at or close to level, with a shallow fall away from the highway so water drains back into the site. Common requirements run from around 5 metres to 10 metres of landing at a gradient no steeper than about 1 in 20, but this varies by authority and by the classification of the road being accessed. Read the adopted design guide for the county, unitary or London borough that acts as highway authority, and read it before the drive is set out rather than after.

Two details get missed. The landing is measured from the highway boundary, which is often not the same as the property boundary shown on the title plan. And the landing must be level across the access as well as along it, because a car parked on a cross-fall of any severity has a door that swings hard.

Gradients beyond the landing

Past the landing, authorities typically allow a steeper running gradient. Figures around 1 in 10 are widely used for the main length of a private drive, with steeper sections tolerated on short runs where the geometry is otherwise sound. Some guides distinguish between drives serving a single dwelling and shared accesses serving several, because a refuse vehicle, a fire appliance or a delivery van has different limits from a family car.

If a shared surface is proposed, the gradient interacts with the drainage and the pedestrian priority arrangement, and the article on shared surface streets covers what officers look for on those. The geometry of the drive itself, meaning widths, radii and turning provision, is a separate exercise set out in the note on private drive geometry.

Where the access serves the strategic road network, none of this local guidance applies in the first instance, because National Highways will assess the proposal against its own standards under Circular 01/2022, as explained in the piece on access onto the strategic road network.

Ground clearance and the change of grade

A gradient limit on its own does not stop a car grounding. What grounds a vehicle is the rate at which the slope changes, at the crest where the landing meets the rising drive and at the sag where the drive meets a level parking area.

Design guides deal with this by asking for transition lengths, a short section at an intermediate gradient between the two, or by specifying a maximum change of grade over a given distance. On a domestic drive the practical test is a long-wheelbase saloon with low front and rear overhangs. On a scheme that will be served by refuse or emergency vehicles, the test is the authority's own design vehicle, and the swept path analysis has to be run over the actual levels rather than over a flat plan.

Set the levels on the drawing. A note saying gradients will comply is not an answer, and highway officers have seen enough of them to treat it as a warning sign.

Keeping surface water off the highway

Water running from a private drive onto the footway is a nuisance in summer and a hazard in winter. Section 163 of the Highways Act 1980 gives the highway authority power to require an owner or occupier to stop water falling from premises onto a footway, and authorities use conditions on planning permissions to secure the same result up front.

The usual solution is a channel drain or a linear gully at the top of the landing, discharging to a soakaway or to the site drainage system, with the landing itself falling towards it. Surfacing matters too. Since 2008 a front garden of more than five square metres surfaced in an impermeable material has needed planning permission unless the water is directed to a permeable area within the curtilage, which is why bound gravel, permeable block paving and a positive drainage route are the default on new accesses.

Do not assume the water can go into the highway drain. That needs the authority's agreement, and it is often refused where the existing system is at capacity.

Steep sites, retaining structures and the highway boundary

On a plot that rises or falls sharply from the road, the level landing has to be cut or built up, and the moment a retaining structure is close to the highway the approval route changes. A structure that retains or supports the highway, or that sits within the highway boundary, needs technical approval from the authority and usually an agreement under section 278 of the Highways Act 1980 for the works themselves.

That has programme consequences. Section 278 agreements take months, need a bond and a fee, and are not something to start after permission is granted if the build is meant to run that summer. Where construction traffic will use a partly built access, the temporary arrangements are a separate conversation, covered in the note on temporary road closures and street works.

Retaining walls above a certain height also affect visibility splays, because the splay has to be kept clear of obstruction above around 600 millimetres. A 900 millimetre retaining wall along the boundary can undo a perfectly good sight line.

The evidence a highway officer wants

1. A long section through the centre line of the access, at a stated vertical and horizontal scale, from the carriageway channel to the parking area.
2. Existing and proposed levels tied to Ordnance Datum, not to an arbitrary site datum.
3. The landing dimensioned, with its length and gradient annotated.
4. Gradients annotated on every length of the drive, with transition lengths shown at each change of grade.
5. Visibility splays drawn on the site plan, with the x and y distances stated and the obstruction height noted.
6. The drainage route, showing where the channel drain sits and where it discharges.
7. A swept path drawing where the access serves more than one dwelling or a vehicle larger than a car.

On a minor scheme this sits in a short transport note or, where the council's list asks for one, in a Transport Statement. A highway officer reading a long section can approve an access in ten minutes. A highway officer reading a paragraph of assurances will ask for the long section and add three weeks to the determination.

Enter your postcode on PlanScope to see which transport and highways documents a site is likely to need before you commit to a levels strategy.

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