Active travel and the walking and cycling isochrone

A walking or cycling isochrone is a line joining every point reachable from a site within a fixed travel time, drawn along the footway and cycle network rather than as a radius. It is the standard way of showing accessibility in a transport chapter, and it is also the single easiest thing in that chapter to draw dishonestly. A circle on a plan is not an isochrone, and a highway officer with local knowledge will spot the difference within a minute.

Used properly it tells you where the scheme's residents can actually get to, which is what mode share arguments rest on.

What an isochrone shows and how it is drawn

The method is straightforward. Take the site access point, build the walkable network from the footway and public right of way data, apply a walking speed, and plot the boundary reached at 5, 10 and 15 minutes. Repeat for cycling with a cycling speed and the cycle-permitted network.

Three details decide whether the result is credible.

The network has to be the real one. Footways on both sides of a road, controlled crossings, underpasses, alleys and public rights of way all count. Severances do too: a dual carriageway with no crossing for 600 m, a railway with a single bridge, a river, a level crossing that is shut at peak times. An isochrone drawn from a road centreline dataset with no crossing logic will show places nobody can reach.

The speed has to be stated. A walking speed of 1.4 metres per second is a common assumption, and it suits a fit adult on level ground. It does not suit an older resident with shopping on a hill, and where the scheme is retirement housing or has a steep approach, say what you have assumed and why.

And gradients and surface quality matter for both modes. A 10 minute cycle isochrone that crosses a busy gyratory with no protected provision overstates what people will do.

Common walking and cycling distance thresholds

Distance thresholds come from national design guidance rather than from policy, so they are a reference point rather than a test.

For walking, the widely used figures are around 400 m to a bus stop, around 800 m or a ten minute walk to local facilities such as a shop, a primary school or a park, and up to around 2 km as an acceptable walk to a rail station where the route is direct and pleasant. Manual for Streets describes a walkable neighbourhood as roughly a ten minute walk to everyday facilities.

For cycling, a five kilometre trip is generally treated as within easy range for an ordinary rider, with longer distances plausible where the route is direct and separated from traffic.

Two cautions. Distance is a poor proxy for whether people will walk, because severance, personal security, lighting and crossing delay matter more than the last hundred metres. And an isochrone that just reaches a facility at the edge of the boundary is not evidence people will use it. Report the walk time to the named facility, not to the edge of the shape.

Where LTN 1/20 design standards apply

Local Transport Note 1/20, Cycle Infrastructure Design, is the national standard for cycle provision in England. It sets out core design principles, requiring routes to be coherent, direct, safe, comfortable and attractive, and it gives geometric standards for lane widths, junction treatments, separation from traffic and transitions.

For a development scheme it applies in two ways. Any cycle infrastructure delivered within the site or on the adjoining highway is expected to meet it, and any route relied on in the accessibility case will be assessed against it. Claiming a cycle route as a benefit when it is an advisory lane on a 40 mph road tends to weaken the argument rather than strengthen it.

Where the highway works are delivered under a section 278 agreement, the highway authority will apply the standard directly, and departures need justification. Design to it from the start rather than negotiating retrospectively.

Active Travel England as a consultee

Active Travel England became a statutory consultee for larger planning applications in England in June 2023. The thresholds are set out in the Development Management Procedure Order and cover major residential schemes at 150 dwellings or more, larger floorspace proposals and sites above a stated area. Verify the current thresholds before assuming a scheme is outside them, because the Order has been amended since.

What that means practically is a further consultee with a specific interest, who will look at the walking and cycling network within and around the site, the quality of connections to existing routes, cycle parking quantity and design, and whether the layout puts active travel first or last. Their assessment tool scores schemes, and a low score generates a recommendation the local planning authority has to address.

The presence of another statutory consultee also affects the timetable, and the general position on who the council must consult and when is covered in the note on statutory consultees.

Engage before submission where the scheme is close to the thresholds. It is far cheaper to move a cycle route on a masterplan than after a consultee response.

Cycle parking quantity and quality

Quantity comes from the adopted local plan or, in London, the London Plan cycle parking standards, split between long stay for residents and staff and short stay for visitors.

Quality is where applications fall down. The recurring failures are consistent:

1. Long stay parking at the far end of a basement with a long ramp and no lift, so nobody uses it.
2. Two-tier racks counted at full capacity when the upper tier is unusable for many riders.
3. No provision for cargo cycles, adapted cycles or trailers, which need larger, level, ground floor spaces.
4. Sheffield stands spaced too closely to allow two cycles per stand in practice.
5. Visitor parking hidden behind the building rather than beside the entrance.
6. No power supply for charging where electric assist is now common.

Provide a proportion of oversized spaces at ground level with step-free access, put visitor stands where a visitor would look for them, and show the layout at a scale where the spacing can be checked. That single drawing removes most consultee comments.

Using isochrones honestly in a transport section

Present the isochrone as evidence rather than as decoration. That means stating the method, the network data, the speed assumed and the date, showing severances on the plan rather than smoothing them out, and listing the facilities reached with the actual walk time to each.

Where the isochrone shows the site is poorly connected, say so and set out what the scheme does about it: a new footway link, a crossing contribution, an upgraded right of way, a bus stop improvement. An honest isochrone plus a mitigation package is a far stronger position than a flattering isochrone that a consultee then dismantles.

The isochrone belongs in the accessibility section of a transport statement on smaller schemes and in the transport assessment on larger ones, with the measures and monitoring set out in a travel plan.

And keep it consistent with the mode share used elsewhere. A transport chapter claiming high walking mode share alongside an isochrone showing nothing within ten minutes is arguing with itself.

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