The town centre vitality section of a retail impact assessment

The vitality and viability section is the part of a retail impact assessment that decides the application. It is where you quantify how much trade your proposal will pull out of nearby centres, set that against the health of those centres, and conclude whether the effect crosses the threshold at which the National Planning Policy Framework says permission should be refused. The sequential test asks whether a better-located site exists. The impact test asks what happens to the centre if yours goes ahead anyway, and the vitality section carries most of that argument.

An impact assessment is triggered for retail and leisure development outside a defined centre once it exceeds the floorspace threshold in the adopted local plan, or 2,500 m² of gross floorspace where the plan sets no local figure. Plenty of local plans set thresholds far lower, sometimes 200 m² in a rural district with fragile high streets, so check the development plan before assuming you are under the bar.

What the vitality section has to establish

The Framework's impact test has two limbs, and they are commonly confused. One is the effect on existing, committed and planned investment in a centre or centres in the catchment. The other is the effect on town centre vitality and viability, including local consumer choice and trade in the centre and the wider retail catchment. The assessment horizon is five years from the date of the application, extending to ten years for major schemes where the centre is in a phase of change.

The conclusion the authority needs is binary in form and evidenced in substance. Either the proposal is likely to have a significant adverse impact on one or more of those considerations, in which case the Framework says it should be refused, or it is not. A section that lists indicators without reaching that judgement sends the case officer back for more information, and the clock keeps running.

Health check indicators and where they come from

A health check is a snapshot of how a centre is functioning. Practice has settled on a recognisable set of indicators, and an assessment that leaves several of them out is easy to pick apart at committee:

1. Diversity of uses by unit count and by floorspace, broken down into convenience, comparison, service and food and drink.
2. Vacancy of street-level units, counted on a stated survey date, with vacant units identified on a plan.
3. Retailer representation, including national multiples present and any published requirements to be in the centre.
4. Pedestrian flows on a counted basis at stated locations, times and days.
5. Rents and yields where published evidence exists for the centre.
6. Accessibility by bus, rail, car and on foot, plus car park occupancy.
7. The condition of public spaces, perception of safety and the extent of recent public or private investment.

The honest difficulty is that rent and yield evidence is rarely available for a small market town, and inventing a figure to fill the row is worse than leaving it blank with an explanation. Where a number does not exist, describe the effect in words and say where the gap is. A case officer will accept a reasoned absence. They will not accept a figure they cannot trace.

Vacancy deserves care because it is the indicator members quote. A single count tells you little. Two or three counts over 18 months, or a comparison against the council's own monitoring where it publishes retail surveys, turns a number into a direction of travel.

Trade draw and diversion

This is the quantitative core. The method is public and has been tested at inquiry for decades.

Start with the turnover of the proposal: net sales floorspace multiplied by a sales density appropriate to the operator type, stated in pounds per square metre and sourced. Then define the catchment and estimate available expenditure within it, using population projections and per-capita expenditure on convenience and comparison goods from a recognised expenditure dataset, with a deduction for special forms of trading. Deduct the turnover of existing and committed floorspace. What remains is the headroom.

Trade diversion then allocates the proposal's turnover across the centres and stores it will draw from, as a percentage from each, with the reasoning stated store by store. The percentages must sum to the proposal's turnover. Convert each diversion into a proportion of that centre's convenience or comparison turnover, and you have the trading impact figure the authority will test.

Illustrative example: a 1,200 m² net food store proposed on an edge-of-centre site. If the assessment puts its turnover at a stated sales density and allocates 35 per cent of that from a town centre supermarket, 20 per cent from the high street's smaller convenience units and the balance from two neighbouring centres and from existing out-of-centre stores, the authority will ask what the 20 per cent means for the half-dozen independents that depend on linked trips. That is where the vitality section either does its job or does not. The figures here are illustrative only.

Cumulative impact with committed schemes

Solus impact is the easy calculation. Cumulative impact is where assessments fall over, because it requires you to add in every extant permission and allocation that has not yet been built, and the list changes between the date you run the numbers and the date the application is determined.

Three practical rules. Search the authority's own committed development schedule rather than relying on the applicant's recollection. Include schemes in adjoining authorities where the catchments overlap, because retail catchments ignore administrative boundaries. And state the cut-off date for the search in the text, so that the officer can see what was known when.

Where a large commitment exists but is stalled, say so and model both scenarios. An assessment that silently assumes a stalled scheme will never be built invites the objector to re-run the arithmetic with it included.

Investment impact against trading impact

The investment limb is separate and often neglected. It asks whether the proposal would undermine investment that a centre is relying on, which might be a committed foodstore anchoring a regeneration site, a public-sector acquisition of a vacant department store, or a mixed-use allocation with planning permission.

The test is not whether the investment is profitable. It is whether your scheme would make it less likely to happen, and the evidence is documentary: the council's own committee reports, published funding decisions, the local plan allocation and any marketing evidence. Where the investment is a public-sector project, the authority will treat harm to it seriously, and a short section conceding that risk and explaining why it is not material is more persuasive than silence.

Defining the catchment

Everything above depends on the catchment, and a catchment drawn to flatter the proposal is the single most common reason an assessment is rejected. Three approaches are used, usually in combination:

• Drive-time isochrones, typically five, ten and fifteen minutes, stated with the assumptions used.
• A household telephone or online survey of shopping patterns by zone, which is the strongest evidence but is expensive and needs a sample size per zone that will stand up.
• The council's own retail study, where one exists and is recent enough to be useful.

Zones should follow how people actually shop rather than ward boundaries. If the local plan evidence base already defines retail zones, use those, because the authority will compare your figures against its own study and any difference in zoning makes the comparison impossible.

Writing conclusions an authority can rely on

The section should close with a short, numbered set of findings that track the two limbs and the five or ten year horizon, each one traceable to a table earlier in the report. State the trading impact on each affected centre as a percentage of that centre's turnover, state the conclusion on investment, and then state whether the combined effect is adverse and whether it crosses the Framework's refusal threshold.

Councils usually expect a retail impact assessment to be authored by someone with retail planning experience, and professional review is strongly advised before submission. A Retail Impact Assessment drafted to the right structure still needs a practitioner to stand behind the expenditure assumptions, and the accompanying retail sequential test has to be consistent with it. Where the proposal also claims employment or regeneration benefits, an Economic Impact Assessment carries those rather than the vitality section. The same discipline of making every figure traceable applies to any evidence section an officer checks line by line, including the room schedule inside a daylight report.

Enter your postcode on PlanScope to see which reports a change of use or new retail unit is likely to need.

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.