A3 road noise: how it affects nearby properties
The A3 is a major dual carriageway from London to Portsmouth and carries motorway-level traffic through much of Surrey and Hampshire, despite being an A-road. Many attractive villages sit close to it, and the Defra strategic noise maps do cover its busiest stretches — so AcoustaPlot can often read a mapped value directly for A3-adjacent homes.
Traffic on the A3: what the 2025 DfT counts show
The A3 was never built in one go. Bypasses, tunnels and widened interchanges have been added to the old London to Portsmouth line for generations, and the 112 DfT count points read like the layers of that history. The middle point sits at 29,400 vehicles a day, yet the quietest tenth of points fall below 6,900 and the busiest tenth reach 83,100 or more. The single highest count is 112,777. Six points pass the hundred thousand mark and 37 pass fifty thousand, while 16 stay under ten thousand, some of which will be slip roads and links that the counts also include.
Begin at the Portsmouth end. The south-western third has 26 count points, a median of 24,800 and a top reading of 64,539. Hindhead is the best known change of character: a twin-bore tunnel about 1.9km long, inside a 6.4km bypass, took traffic off the crossroads and left the old A3 by the Devil's Punch Bowl closed to vehicles and now heathland. The middle third is the heavy one, with 28 points, a median of 46,200 and a high of 107,630. The north-eastern third, 58 points on the way to King William Street, has the lowest median at 22,700 but the highest single count, 112,777, and it still includes single carriageway through Battersea, Clapham and Stockwell.
On the road from London to Portsmouth the lorry share is small. Across the 112 count points the median is 2.5 per cent, one point in ten is above 4.5 and the highest is 8.3, with 0.4 the lowest. That is why the indicative table uses 2.5 per cent. The A3 noise story is therefore driven by car volume and speed, from 30 mph in Wandsworth to 70 mph on the Esher bypass, more than by heavy vehicles.
| Quarter of points carry under | 14,800 vehicles/day |
|---|---|
| Median point | 29,400 vehicles/day |
| Three-quarters carry under | 59,700 vehicles/day |
| Busiest tenth carry over | 83,100 vehicles/day |
| Busiest single point | 112,777 vehicles/day |
The A3 on the ground
- Runs from King William Street in the City of London to Old Portsmouth; published length figures conflict, between about 67 and 72 miles. en.wikipedia.org
- Mostly dual carriageway or wider, but single carriageway remains through urban Battersea, Clapham and Stockwell and through Waterlooville. en.wikipedia.org
- Hindhead's twin-bore tunnel is about 1.9km long within a 6.4km bypass; the southbound tube opened on 27 July 2011 and the scheme cost £371m. tunneltalk.com
- The old A3 by the Devil's Punch Bowl is closed to vehicles and now heathland; the old route south-west of the crossroads is the A333. assets.publishing.service.gov.uk
- Five years on, local noise impacts at Hindhead were judged as expected or better, as old A3 traffic fell more than predicted. assets.publishing.service.gov.uk
- Speed limits vary widely: 30mph in the Wandsworth urban section, 50mph through Guildford, and 70mph on the Esher bypass and at Wisley interchange. en.wikipedia.org
How loud is the A3, and how fast does it fall away?
The A3 table is a guide to how distance matters, and nothing more. It assumes open, flat ground with no screening and a steady 50 mph, which this road does not keep, given 30 mph in Wandsworth and 70 mph on the Esher bypass. On a typical section, 29,400 vehicles a day, a home 20 m from the nearest carriageway is indicated at 69 dB Lden, then 65 dB at 50 m, 63 dB at 100 m and 60 dB at 200 m. On a busy section, 83,100 a day, the same distances give 73, 69, 67 and 64 dB. All eight values exceed Defra's 55 dB Lden reporting threshold. Actual addresses will vary with cuttings, buildings and fences, so these figures show the effect of distance, not a prediction for any house.
| Flow | 20 m | 50 m | 100 m | 200 m |
|---|---|---|---|---|
| Typical section (29,400 vehicles/day) | 69 | 65 | 63 | 60 |
| Busiest tenth of sections (83,100+ vehicles/day) | 73 | 69 | 67 | 64 |
Areas near the A3
Passing through: Greater London · Surrey · Hampshire.
The Hindhead Tunnel dramatically reduced noise for the Devil's Punch Bowl area, a reminder of how much infrastructure shapes local conditions. Elsewhere, homes near Guildford, Ripley and Cobham can sit close to high flows. AcoustaPlot distinguishes between mapped and calculated sections so you know exactly how your A3 estimate was derived.
Recent on the A3
A £317 million scheme to improve the M25 Junction 10/A3 Wisley interchange near Guildford — widening the A3 carriageway and rebuilding the junction's bridges and slip roads, while also restoring surrounding heathland — ran from summer 2022 and was due to complete in spring 2026.
Source: https://nationalhighways.co.uk/our-roads/south-east/m25-junction-10/
How AcoustaPLOT assesses A3 noise for your property
On the A3 the nearest count matters more than any road-wide figure. AcoustaPLOT looks for one of the 112 DfT count points on the A3 itself within 8 km along the road, and takes that measured flow and lorry share. Because the road's flow changes from third to third, with medians from 22,700 to 46,200, an average would suit none of them. Having chosen the count, it adds the real distance to the carriageway, the terrain, ground cover, buildings or barriers in between, and noise from any other roads or rail nearby. It reports the day-evening-night (Lden) and night-time (Lnight) levels at your facade, and reads Defra's mapped value for any railway noise where available.
Check my property near the A3 →
A3 noise: common questions
Did the Hindhead Tunnel quieten the old A3 route?
The tunnel is about 1.9km long, set in a 6.4km bypass, and the southbound tube opened on 27 July 2011 at a cost of £371m. A five-year evaluation judged local noise impacts at Hindhead as expected or better, because old A3 traffic fell by more than predicted. The old road beside the Devil's Punch Bowl is closed to vehicles and is now heathland. Addresses elsewhere on the A3 do not share that change.
Is the whole A3 dual carriageway?
Mostly, yes: it is mostly dual carriageway or wider, but single carriageway remains through urban Battersea, Clapham and Stockwell and through Waterlooville. Speed limits vary widely too, with 30 mph in the Wandsworth urban section, 50 mph through Guildford and 70 mph on the Esher bypass and at Wisley interchange. That is why the 50 mph assumed in the indicative levels is only a middle value.
Do the 2025 A3 counts reflect the Wisley interchange rebuild?
Probably not entirely. A £317 million scheme at the M25 junction 10 and A3 Wisley interchange, widening the carriageway and rebuilding bridges and slip roads, ran from summer 2022 and was due to complete in spring 2026. The 2025 count year therefore falls inside the construction period, so a count point close to Wisley may show flows from the works period rather than the finished layout.
Where on the A3 do the counts peak?
The north-eastern end, towards London, holds the highest single count at 112,777 vehicles a day, and six points on the road exceed a hundred thousand. The highest median, though, is in the middle third at 46,200, against 24,800 in the south-western third and 22,700 in the north-eastern one. Overall, 37 of the 112 points are above fifty thousand, so busy locations are common but the very top readings are few.