A worked parking stress survey for an urban site
Parking stress is parked vehicles divided by usable kerb capacity. Here is the catchment, the deductions, the survey timing and a worked calculation officers will accept.
A parking stress survey measures how full the kerbside already is, expressed as parked vehicles divided by usable kerb capacity. Anything at or above roughly 80 per cent is treated by most highway officers as a street working at practical capacity, and that is the number your application either has to beat or has to answer. This parking stress survey worked example follows the kerbside counting method developed by the London Borough of Lambeth, which is the approach most English authorities now ask for on conversions and small infill schemes.
The method is public, the arithmetic is simple, and almost every argument about the result comes down to what was excluded from the kerb length.
Defining the survey area and its kerb length
Start with a walking catchment rather than a radius drawn on a map. Most councils expect streets within 200 metres walking distance of the site frontage, measured along the footway, although 100 metres and 250 metres both appear in local guidance. Agree the catchment with the highway officer before you survey, because redrawing it afterwards looks like shopping for an answer.
Measure each street's kerb length on both sides from a scaled plan or an online measuring tool, then deduct everything a car cannot legally or physically park across:
- vehicle crossovers and dropped kerbs serving driveways
- junction protection, conventionally 10 metres either side of a junction mouth
- single and double yellow lines, and any residents-only bay outside the permitted hours you are testing
- bus stops, loading bays, disabled bays, taxi ranks and electric vehicle charging bays
- pinch points, build-outs, pedestrian crossings and their zig-zags
- private forecourts and anything behind a boundary line
What is left is the available kerb length. Convert it to spaces by dividing by the length allowed per car, conventionally 5 metres on an unmarked kerb. Some authorities use 5.5 or 6 metres. Confirm the figure with the highway authority and state it in the report, because a change from 5 to 6 metres moves the stress figure by about 17 per cent on its own.
Counting method and survey nights
Count when residents are at home and visitors are not. The Lambeth approach surveys between 00:30 and 05:30, on one midweek night and one weekend night, giving two independent results rather than an average of a single night's guesswork.
Avoid school holidays, the fortnight either side of Christmas, and any week with a local event that changes travel behaviour. Record the date, the times each street was walked, the weather, and the direction of travel. Photograph anything unusual, such as a skip occupying eight metres of kerb, and deduct it from that night's capacity with a note.
Count every parked vehicle on the public highway inside the catchment, including vehicles parked illegally, because they occupy space that a new resident's car would otherwise use. Do not count vehicles on private driveways or forecourts, and do not count the same vehicle twice where a street is walked in two passes.
Calculating stress as a percentage
The calculation is one line. Parking stress equals parked vehicles divided by capacity in spaces, multiplied by 100.
An illustrative worked example for a four-street catchment around a proposed six-bedroom house in multiple occupation:
| Step | Figure |
|---|---|
| Total kerb length, both sides, four streets | 1,240 m |
| Deductions (crossovers, junctions, restrictions, bus stop) | 430 m |
| Available kerb length | 810 m |
| Capacity at 5 m per vehicle | 162 spaces |
| Midweek count, 01:00 to 03:00 | 139 vehicles |
| Weekend count, 01:00 to 03:00 | 148 vehicles |
| Midweek stress | 86 per cent |
| Weekend stress | 91 per cent |
Those figures are illustrative rather than measured. On that result the honest conclusion is that the street is already at capacity, and the application has to deal with demand rather than deny it. A survey that comes back at 62 per cent midweek and 70 per cent at the weekend supports a very different argument.
Report both nights separately. Averaging them hides the weekend peak, and the weekend peak is usually the one that decides the case.
Exclusions that decide the argument
Three deductions carry most of the dispute.
Crossovers are the first. Every dropped kerb removes roughly its own width plus the manoeuvring space either side, and on a street of 1930s semis with driveways that can be half the frontage. Officers will check your deduction against street imagery.
Junction protection is the second. The 10-metre convention comes from highway practice rather than from statute, so if the local authority applies a different figure, use theirs and say so.
Residents' permit hours are the third. Where a controlled parking zone operates from 9am to 5pm, the kerb at 02:00 is uncontrolled and your capacity should reflect that. Surveying at midnight and then deducting daytime restrictions inflates the stress figure, and a transport officer will spot it.
Reading the result against local policy
A high stress figure is not fatal, and a low one is not a free pass. What the survey does is set the baseline that your parking provision, cycle storage, car club membership or permit-free agreement has to work against.
Where stress is high, the usual routes are a permit-free obligation secured by a section 106 agreement or a unilateral undertaking, on-site parking, or a reduction in unit numbers. Where the borough operates no controlled parking zone, a permit-free obligation is unenforceable and officers know it, so a different answer is needed. Set the survey result alongside census travel-to-work data for the ward and the accessibility of the site by public transport, then argue the trip generation rather than the headline percentage. A short Transport Statement is often the right container for that argument on a small scheme.
Criticisms highway officers make
The same objections recur, and all of them are avoidable.
Surveys done on a single night. Surveys done in August. Capacity calculated on gross kerb length with no deductions, or with deductions so generous that the street appears empty. Catchments drawn to include a quiet cul-de-sac 400 metres away. Counts taken at 22:00, when a third of residents are still out. No photographs, no street-by-street table, no raw data appendix.
Give the officer the raw counts by street and by night in an appendix. And if the numbers are defensible, transparency helps you. If they are not, you want to know before submission rather than after.
Presenting the survey with the application
Put the method, the catchment plan, the deduction table by street, the two nights of counts and the stress calculation in one document, then summarise the conclusion in three or four sentences in the planning case. Cross-refer it from the Planning Statement rather than repeating the arithmetic there.
Include a plan showing the surveyed streets with deductions marked, dated photographs of each street, and a statement of who carried out the count. An unsigned survey with no methodology section invites the officer to commission their own, and theirs will not be kinder than yours.
The full report sits under the Parking Survey report type, which sets out what a submitted survey normally contains.
This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.
You can see which reports a conversion scheme is likely to need by entering a postcode. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
What parking stress percentage is considered full?
Around 80 per cent is widely treated as the point at which a street is working at practical capacity, because the remaining gaps are too short or too scattered to use. Some authorities apply 85 per cent. Check the local highway authority's own guidance, since the threshold is convention rather than statute and the figure you adopt should be stated in the report.
How many nights should a parking stress survey cover?
Two as a minimum: one midweek night and one weekend night, each counted between roughly 00:30 and 05:30 when residents are at home. Report the two results separately rather than averaging them. Avoid school holidays, the period around Christmas and any week with a local event that changes normal parking behaviour.
Do I count illegally parked cars?
Yes. A vehicle parked on a yellow line is occupying kerb space that a new resident's car would otherwise compete for, so it belongs in the count. The restricted length is still deducted from capacity, which pushes the stress figure above 100 per cent on some streets. Explain that in the text rather than capping the result.
How much kerb length does one parked car need?
Five metres is the usual convention on an unmarked kerb, with some authorities using 5.5 or 6 metres. The choice matters: moving from 5 to 6 metres cuts capacity by about a sixth and raises the stress percentage accordingly. Agree the figure with the highway officer before surveying and state it in the methodology.
Will a permit-free agreement solve a high stress result?
Only where a controlled parking zone exists, because the obligation works by denying future occupiers a resident's permit. Outside a zone there is nothing to withhold and officers treat the offer as unenforceable. In that situation you need on-site parking, fewer units, or evidence that the occupiers of the proposed use own few cars.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.