M3 Westbound Traffic (Towards Winchester and Southampton)

If you are heading westbound on the M3 — out of London and the M25, through Bagshot, Camberley and Fleet, past Basingstoke and Winchester to Eastleigh and the M27 — this page covers your side of the motorway. Traffic is rarely the same on both carriageways, and neither is the news.

Heading the other way? See M3 eastbound traffic »

Looking for M3 southbound?

You are in the right place. The M3 runs south-west to north-east, so National Highways signs and reports it as eastbound and westbound, not north and south. If you searched for M3 southbound, the carriageway you want is westbound — because the M3 runs south-west as it heads for the coast.

We use National Highways’ own wording on every news item on this site, because that is what the overhead signs and the official reports say. Being in the right lane matters more than the compass.

How busy is the M3 westbound?

The Department for Transport counts each carriageway separately. These are the 2025 westbound figures for all 15 measured stretches of M3 mainline, busiest first.

© M3Traffic.co.uk · Statistics from the Department for Transport

The busiest westbound stretch is J13 Chilworth to J14 (M27), at 71,293 vehicles a day on that carriageway alone. For both carriageways together see how busy the M3 is junction by junction.

A note on direction: because the M3 runs south-west to north-east, the Department labels some of its count points E/W and others N/S. We have mapped them by junction order, so flows towards the lower junction numbers are shown as eastbound and flows towards Junction 14 as westbound. That is our reading of their data rather than their own label, and we would rather say so than leave it unstated.