Severance, desire lines and pedestrian route quality

Pedestrian severance assessment is the part of a transport chapter that officers read and consultants skimp on. Severance is the degree to which a road, a railway, a watercourse or a development itself makes it harder for people to reach the places they want to reach on foot. It is assessed by looking at where people actually want to walk, how long they wait, and what the route feels like, rather than by counting the footways that exist.

Appraisal practice classifies severance effects as slight, moderate or severe, using changes in traffic flow, traffic speed and carriageway width alongside the availability of crossings. The Department for Transport's transport analysis guidance sets out that framework. Development management rarely needs the full appraisal machinery, but it does need the same logic.

What severance means in appraisal terms

Two kinds of severance appear in planning submissions. Traffic severance is the effect of vehicle flow and speed on the ability to cross a road, and it worsens gradually as flows rise until crossing becomes a deliberate decision rather than an unconscious one. Physical severance is the effect of a barrier, such as a railway embankment, a dual carriageway with guardrail, a river with crossings 900 metres apart, or a gated development that closes off a through route.

Development can relieve severance or create it. A scheme that opens a new footpath link between two estates reduces it. A scheme that intensifies traffic on a residential through road, or that replaces an informal cut through with a private courtyard, increases it. Both effects belong in the Transport Assessment, and the second is the one applicants tend to leave out.

The assessment is about people reaching destinations, so name the destinations. Primary school, GP surgery, convenience shop, bus stop, park, secondary school, railway station. Then test each one.

Finding the desire lines rather than the designed route

A desire line is the route someone would take if nothing stopped them, drawn from origin to destination without regard to the footway layout. Designers draw routes. Residents walk desire lines, and the gap between the two is where severance lives.

Finding them takes a site visit, ideally twice: once at the morning school run and once in the early evening. Look for worn grass, gaps in hedges, kerb scuffing, pedestrian guardrail with a bend in it, informal crossing points between parked cars, and the position of dropped kerbs that nobody uses. Aerial imagery shows beaten paths clearly on open ground.

Then draw the desire line on a plan as a straight dashed line, and draw the available walking route beside it as a solid line. The ratio between the two lengths is a number anyone can understand. A 240 metre desire line served by a 700 metre walking route is a severance problem whatever the footway width.

Record the obvious trip generators within walking distance using the thresholds in Manual for Streets, which describes walkable neighbourhoods with most facilities within around 800 metres. Mark the ones your site cannot reach without a detour and say so plainly.

Crossing delay and the perception of safety

Delay at a crossing deters walking out of proportion to the time lost. A pedestrian who waits 40 seconds at a signal, twice, on a 10 minute journey has lost little time but has had the experience of being made to wait by traffic, and will drive next time. Where the authority has signal timing data, ask for it, because the average wait at a staggered crossing with separate stages is often much longer than the design intent.

Perceived safety is separate from recorded collisions. Collision data at a location may be clean precisely because nobody walks there. State that explicitly where it applies, because a clean five year record is routinely presented as evidence that a route is fine when it is evidence that the route is unused.

The factors that change perception are not exotic. Carriageway width at the crossing point, vehicle speed, sightlines around parked cars, lighting, overlooking from buildings, and whether the crossing is on the desire line or 60 metres off it.

What a walking route audit records

A route audit walks each identified route and scores it, segment by segment. The things worth recording are footway width at the narrowest point, surface condition and trip hazards, continuity across side roads, dropped kerbs and tactile paving, gradient and cross fall, lighting coverage, overlooking and natural surveillance, street clutter, and the type and position of each crossing.

Do it as a table with photographs keyed to a plan. Officers and inspectors can then see which segment fails and why, and the mitigation discussion becomes specific. The audit also feeds the accessibility case in a Travel Plan, where a claim about walking mode share needs a walkable route behind it.

Accessibility standards give the dimensional benchmarks. The Department for Transport's Inclusive Mobility guidance covers footway widths, crossing design and tactile surfaces, and it is the document to quote when arguing that a 1.2 metre pinch point past a bus shelter is not an acceptable route to a school. Our note on accessible parking dimensions, numbers and distances deals with the related point at the arrival end of the journey.

Illustrative example: an audit of a 620 metre route from a 70 dwelling site to a primary school finds three segments at or below 1.5 metres, one uncontrolled crossing of a 7.3 metre carriageway with parked cars on both sides, and no dropped kerb at the final side road. All dimensions are illustrative.

Mitigation that actually changes behaviour

Ranked roughly by effect on walking, the measures that work are a new link that shortens the desire line, a controlled crossing placed on the desire line, a continuous footway across a side road, build outs that reduce crossing distance, removal of guardrail that forces a detour, and lighting. Widening a footway from 1.8 to 2.0 metres rarely changes anyone's behaviour.

Fund the measures through the right mechanism. Works within the highway need a section 278 agreement with the highway authority, which takes longer than applicants expect and should be programmed from the outset. Contributions towards an off site crossing need to satisfy the necessity, direct relation and fair and reasonable scale tests in the Community Infrastructure Levy Regulations.

Where the school run is the governing trip, the measures interact with wider restrictions, and our piece on school access, drop off, school streets and restrictions sets out how authorities combine them.

Where severance carries enough weight to refuse

Severance on its own rarely refuses an application. It refuses applications when it combines with something else: a site that policy treats as accessible but which the audit shows is not, a scheme that depends on a walking mode share the route cannot deliver, or a loss of an established public route without replacement.

The strongest form of the argument is the mismatch between a submitted Travel Plan and the physical route. If the plan claims a 20 per cent walking mode share to a station, and the only route to that station crosses an unsignalised distributor road with no dropped kerbs, the plan is not deliverable and the trip generation underpinning the junction modelling is wrong. That is an evidence failure rather than a matter of judgement, and it is much harder for an applicant to argue away.

Be careful about overstating it. Many sites in suburban England have imperfect walking routes, and the question is whether the development makes matters worse or depends on a standard the route cannot meet.

Drawing the analysis so a committee can read it

One plan, one table and three photographs will do more than 20 pages of text. The plan shows the site, the named destinations, the desire lines as dashed, the available routes as solid, and the crossings marked with their type. The table carries the audit by segment. The photographs show the worst pinch point, the uncontrolled crossing and the missing dropped kerb.

Then write three paragraphs: what the routes are, where they fail, and what is proposed. Put the detail in an appendix. A case officer writing a report under time pressure will lift your plan into the committee papers if it is legible, and that is the outcome you want.

Walk the routes yourself before anyone writes a word. Enter your postcode on PlanScope to see which transport documents your site is likely to need, and have any draft reviewed before submission. PlanScope provides AI-assisted draft reports for planning applications. We do not guarantee planning approval. This is general guidance, not legal advice, so check the position with your local planning authority or a qualified professional before relying on it.