Checking aircraft, road and railway noise before choosing a London home

Noise is not one measurement. Aircraft, roads, railways and underground trains can affect a home differently. A map can help you identify questions to investigate, but an outdoor average cannot tell you exactly what you will hear inside a particular bedroom.

notbad keeps three mapped-noise checks and the Tube-track setback independent. You can adjust each noise limit, choose daytime or nighttime, and decide which checks belong in your search.

What the mapped averages tell you

The aircraft layer uses Defra's 2022 noise mapping. It describes average exposure rather than individual flight paths or a live departure feed. The activity year for each airport is not confirmed in this local pack, so a recent catalogue update must not be mistaken for recent flight activity.

The road and railway layers use Defra's 2022 mapping based on 2021 activity. They model outdoor noise, rather than current readings or conditions inside your home. Daytime covers 07:00–23:00; nighttime covers 23:00–07:00.

The source models and the building answer different questions. A mapped value is useful for comparing the supplied outdoor evidence. It does not account for the exact room, windows, construction or your sensitivity to intermittent sounds.

How the filter uses your limit

A supplied value strictly below the selected limit passes the relevant noise check. A value equal to or above the limit removes that place from the matching area. Lowering a limit makes that condition more selective.

Each source remembers separate daytime and nighttime limits. Those periods are alternatives within one map filter; they do not add separate points. A postcode report shows both periods for each source, independently of the period selected on the exploration map.

The starting values in the app are screening choices, not official definitions of quietness. Use them to explore trade-offs, not as a certificate that a home will be quiet.

Missing data does not mean silence

Noise maps do not provide a usable value everywhere. In this app, a missing noise value does not exclude a place. The result remains unknown evidence, and the information panel explains that policy.

For road and railway noise, the published data begins at 40 dB by day and 35 dB at night. A blank value must not be displayed as zero or invented as a lower measurement. The app preserves the distinction between a supplied value and no supplied reading.

This is why a green area is not the same as a verified quiet area: it meets the chosen exclusion policy along with the other selected conditions.

Why the Tube setback is separate

The Tube check removes an approximate 100-metre setback around selected Underground tracks. The sections come from the April 2026 TfL non-folded-cycle permission map, combined with mapped track geometry. Some permitted sections are in tunnels.

Bicycle permission does not establish whether a tunnel is shallow or deep. The setback uses distance as a warning sign; it is not measured noise, a vibration model or a guarantee about buildings outside it. It also does not change when you select different rail lines for walking access.

Questions to take to a viewing

Check which source caused concern and which period matters to your routine. Visit at a relevant time when practical, listen from the rooms you would use, and distinguish continuous background sound from individual events. Ask about the actual building and any known noise issues rather than treating an area-level average as an indoor assessment.

If a result is unknown, make that uncertainty part of your viewing checklist. It is a reason to gather more evidence, not a reason to assume the issue is absent.

Sources

• Defra explanation of the 2022 noise maps
• Defra aircraft noise dataset
• TfL cycling map
• OpenStreetMap attribution

Compare sources at the same point

At the Hounslow West and Hounslow Heath reference positions, both reports supply aircraft readings but their road averages differ substantially. At the Richmond examples, two aircraft readings are supplied and one is absent. The Hounslow, Richmond upon Thames and Tower Hamlets comparisons retain exact coordinates and both periods. A lower road average cannot cancel an aircraft reading, and a blank value cannot establish silence.