How AcoustaPLOT calculates your noise risk
AcoustaPLOT turns the same national datasets that inform UK planning policy into a clear, plain-English answer — using recognised standards, and honest about the limits of modelled data.
Real datasets, not estimates from nowhere.
The data we use
From your geocoded address we query real ground elevation data — a coarse global elevation model for the initial screening estimate (falling back to a flat-site assumption where even that isn't available), and for Acoustic Barrier Design a layered lookup that tries real UK Environment Agency LIDAR survey data first (around 1 metre resolution) and only falls back to that coarser global model where LIDAR doesn't cover a given point — Defra Strategic Noise Maps (END Round 4, 2022), Department for Transport AADF traffic counts, OS OpenRoads and MasterMap, and Network Rail geometry.
Where LIDAR ground data is not available for your address, the Barrier tool falls back to Mapbox elevation data and the Screening report to Open-Meteo elevation data. Both are coarser than LIDAR, and your report states which ground source it used.
One calculates the noise. One calculates the fence.
Noise Risk Screening
For road traffic we calculate the level ourselves with the UK Calculation of Road Traffic Noise (CRTN 1988) method applied to DfT traffic data (a DfT count on the road itself where one exists, otherwise a stated estimate for that class of road), converted to Lden and Lnight; Defra's road noise map is never used as the reported road figure. For railways, where your property falls within Defra END coverage we report Defra's modelled rail level directly; elsewhere we estimate it. A property affected by both a road and a railway has those two separate exposures combined by logarithmic energy addition into one overall figure, and every headline figure in the report is tagged with where it came from.
Acoustic Barrier Design (ISO 9613-2)
We extract a terrain cross-section from real elevation data — real UK Environment Agency LIDAR survey data (around 1 metre resolution) wherever it covers the site, falling back to a coarser global terrain model only where LIDAR doesn't reach, and to a flat-site assumption if neither is available — along the source-to-property line and compute octave-band attenuation (divergence, atmospheric absorption, ground effect and barrier diffraction) to ISO 9613-2 §7.4. A single-ray calculation that treats the fence as infinitely long — iterating barrier heights 1.0–6.0 m to find the insertion loss at each — is what most published barrier tables use, but it materially overstates the benefit of a real, finite-length domestic garden fence. For the barrier height and return length we actually recommend, we instead integrate along the road as a line source and account for diffraction around the ends of the fence as well as over its top, which is a more realistic model of a garden boundary. The single-ray table is retained on this site only as a reference figure for long, continuous highway-scale schemes, and is never the recommended height for a domestic barrier. We deliberately use ISO 9613-2's own diffraction term (not the older Maekawa nomograph some consultants still use) rather than converting between the two, and where the two diverge our figure does not recommend a lower barrier than the Maekawa convention would — we would rather over-specify a fence than under-specify one.
Declared limitation. The barrier insertion-loss figure has been verified for formula correctness and geometry only. Every case in our validation archive to date is a prediction, not a measurement — we have not yet matched a real barrier's measured before-and-after noise levels to what the model predicted for it. Treat the stated dB reduction as indicative, not guaranteed, until a measured case is found and added to that record.
Risk bands
| Rating | Lden | Lnight | Meaning |
|---|---|---|---|
| LOW | < 45 | < 35 | At or below typical background. No significant impact indicated. |
| LOW-MODERATE | 45–50 | 35–40 | Perceptible, but below the levels our screening treats as significant for health. |
| MODERATE | 50–55 | 40–45 | Potential for moderate annoyance; glazing/ventilation relevant. |
| MODERATE-HIGH | 55–60 | 45–50 | Approaching our SOAEL-informed screening level; adverse effects on sleep and concentration. |
| HIGH | 60–65 | 50–55 | Within our SOAEL-informed screening band; regular disturbance and documented health effects. |
| HIGH-SEVERE | 65–70 | 55–60 | Above our SOAEL-informed screening level; significant health effects including cardiovascular risk. |
| SEVERE | ≥ 70 | ≥ 60 | Approaching our UAEL screening level; professional survey and mitigation strongly advised. |
Reference thresholds: WHO road-noise guideline 53 dB Lden · SOAEL proxy 63 dB (England, owner-verified) · UAEL proxy 69 dB. The bands and the SOAEL/UAEL proxies are AcoustaPLOT's own screening categories, informed by (not identical to) the official policy concepts; they are not a statutory or planning determination.
Accuracy & honesty
Every figure is a calculated estimate with real uncertainty, not a measurement. Road levels are AcoustaPLOT's own CRTN-based calculation from traffic data, and the same goes for Acoustic Barrier Design; a rail level taken directly from Defra mapping is a published modelled figure, but still a model. Our risk bands are 5 dB wide, so a result near a band boundary may in reality sit in the adjacent band, and a result we calculate or estimate ourselves can sit further out again — which is why every report states the band and the range together. Like a flood-risk map, AcoustaPLOT is a screening model, not an on-site measurement — where an exact measured figure is needed, a Measured Acoustic Survey survey is the appropriate route.
Standards & references
- ISO 9613-2:2024 — outdoor sound propagation
- Calculation of Road Traffic Noise (CRTN), DoT/Welsh Office, 1988
- WHO Environmental Noise Guidelines for the European Region (2018)
- BS 8233:2014; Noise Policy Statement for England (NPSE, 2010)
- Defra Strategic Noise Mapping (Environmental Noise Directive, Round 4, 2022)
Methodology version: methodology-2026-09-05. If this page changes, this identifier changes with it — quote it if you need to show which version was in force when you bought your report.