Baseline tables in a parking survey

Baseline tables in a parking survey are the part a highway officer reads first and the part that decides whether the rest of your application is believed. They record, street by street, how much usable kerb exists, how many vehicles were parked on it at the survey hour, and the resulting stress figure as a percentage. Get the capacity measurement wrong and every conclusion built on it falls with it.

The survey itself is simple enough to do badly. Counting cars is easy. Defining what counts as available kerb, on a street with dropped crossings, a bus stop clearway and three skips, is where surveys diverge from each other by twenty percentage points.

What the survey has to record and when

A parking survey measures overnight residential demand, because that is when on-street parking is at its fullest and when a new conversion adds its occupants. Daytime counts tell you about shoppers and commuters, which is a different question.

The convention most English and Welsh authorities accept is the overnight approach developed by the London Borough of Lambeth and now used far beyond London. It surveys between 00:30 and 05:30, on the basis that vehicles parked in that window are residents rather than visitors, and it records the whole of each street within a defined walking distance of the site.

Each survey run produces, per street:

• the length of kerb available for parking, in metres, on each side
• the theoretical capacity in vehicle spaces
• the number of vehicles observed parked
• the stress figure as a percentage of capacity
• notes on obstructions, controlled hours and any unusual conditions

Two runs are normal: one on a midweek night, one at the weekend. And a single night is an anecdote, not a baseline.

Survey nights, times and exclusions

Choose neutral weeks. School holidays, the fortnight either side of Christmas, bank holiday weekends and local festival dates all distort residential parking, usually downwards, which is the direction that flatters an applicant and that officers have learned to distrust.

Weather belongs in the record. Heavy rain or snow changes where people park and whether they drive at all. So does a street closure for works, a nearby event, or roadworks that have suspended a row of bays.

Where a Controlled Parking Zone applies, note its hours. A street with restrictions from 8am to 6.30pm behaves very differently overnight, and the survey window may fall entirely outside the controlled period. That is not a flaw, but the table has to say so, because the officer's question will be whether the zone has capacity for another permit.

Measuring kerbside capacity consistently

This is the step that decides the answer. Capacity is derived from the measured length of unobstructed kerb divided by an assumed length per vehicle, commonly 5.0 metres and sometimes 6.0 metres where the authority's own guidance says so. Marked bays are counted as marked, not calculated.

Deduct, and record the deduction:

• dropped kerbs and vehicle crossovers, plus a margin either side
• junction protection, normally taken to the extent of the junction markings
• bus stops and their clearways
• loading bays, disabled bays and residents-only bays where these are separately counted
• fire hydrant markings, pinch points and any length where parking would block a carriageway

Do the measurement with a wheel or from scaled aerial imagery checked on site, and state which. Where a street has unmarked frontage parking that residents use informally over a dropped kerb, show it separately rather than silently including it.

Keep the same assumption on every street in the survey. A table that uses 5.0 metres in the street with low demand and 6.0 metres in the busy one is the fastest way to lose a highway officer's confidence in the whole submission.

Calculating stress as a percentage

Stress is the number of vehicles parked divided by capacity, expressed as a percentage. A street with 40 spaces and 34 cars sits at 85 per cent.

Practitioners and officers commonly treat the mid-eighties as the point at which a street is effectively full, on the practical reasoning that a driver circling for the last space or two cannot find them. That is a working convention rather than a national standard, and no national policy document sets a stress threshold. Say so in the report instead of presenting 85 per cent as a rule.

Report the figures to one decimal place at most. False precision invites a challenge about measurement accuracy that the survey cannot win.

Street by street presentation

Present every street separately, then give a total. An averaged figure across a survey area hides the street that matters, which is almost always the one directly in front of the site.

A map keyed to the table earns its space. Number each link, show the extent of measured kerb and mark the exclusions, so the officer can check one length without re-surveying the area. Where a street is long, split it at junctions and keep the split consistent across both nights.

Then give the comparison that answers the application: existing demand, demand after the proposal using a stated ownership assumption, and the resulting stress. The ownership assumption needs a source, whether that is census travel-to-work and car availability data for the output area, the authority's adopted parking standards, or trip and parking data from a recognised database. A figure plucked from experience will be treated as such.

For a conversion scheme the sensible position is often to accept that some overspill occurs and to show it is small against measured capacity, rather than to claim zero demand from flats that will plainly be occupied by people who own cars.

Weather, holidays and validity

Officers ask how old the survey is. There is no fixed shelf life, and most authorities take a view somewhere around a year for a street whose character has not changed. A new Controlled Parking Zone, a large completed development nearby or a change to the restrictions resets it.

Where a survey is older, the honest options are a short validation count on one night or a frank statement that the earlier survey is being relied on and why conditions have not changed. Resurveying one night is usually quicker than arguing about it.

Conclusions a highway officer will accept

Write the conclusion as a set of findings, not as an advocacy passage. Give the measured capacity, the observed demand, the stress on both nights, the assumed additional demand with its source, and the resulting stress. Then state the judgement and the uncertainty in it.

The surveys that fail do so for a short list of reasons: one night only, capacity assumed rather than measured, exclusions not deducted, a holiday week, averaging across the area, and a conclusion that does not follow from the table above it.

A parking survey rarely travels alone. On a larger scheme it sits alongside a Transport Assessment, and the two documents need the same baseline, the same survey dates and the same ownership assumptions. Where the proposal also affects servicing or refuse collection, the figures in the waste storage calculations and the swept path drawings should match the kerb lengths you have just measured, and the same discipline applies to the utilities capacity evidence for the same site. Internal contradictions between supporting documents are found by officers more often than applicants expect.

One illustrative case. A nine-flat conversion in a terraced street with 62 measured spaces across two sides, 55 cars on the midweek night and 58 at the weekend, giving stress of 89 and 94 per cent. The street is full. The useful submission is not a lower count but a car-free scheme with a permit-free condition, cycle parking at 1.5 spaces per flat and the stress table shown openly.

A drafted Parking Survey gives you the structure, the headings and the calculation framework, with the counts and measurements still to be collected on site by someone who walks the street.

This is general guidance, not legal advice, and parking standards vary between authorities, so check the adopted standards and any local survey methodology with your local planning authority before committing to a survey design. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. Enter your postcode on PlanScope to see which transport and parking documents your site is likely to need.