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Location from the National Highways junction reference. Nearest towns: Watford, Radlett, Hemel Hempstead, Rickmansworth.
Wider area: counting every road within 3 miles — local streets, A-roads, everything — 1,383 collisions are on record, 14 of them fatal. That figure follows how built-up the area is, so it is shown for context and is not what the ranking uses.
Department for Transport STATS19 police collision records on the M25 itself, within 2 miles of J21. This is the free summary — the full breakdown by severity, weather, road surface, time of day and individual record is in the blackspot report.
📊 Full collision analysis for M25 J21 → 9 of 33 junctions on the M25 · see where it ranks nationallyM25 J21 is at St Albans & Bricket Wood. National Highways signs it as M1 South. The nearest town is Watford.
Live incidents for the whole M25 are listed on the M25 traffic page, updated every 5 minutes from National Highways.
Police STATS19 records show 112 collisions on the M25 within 2 miles of J21, including 1 fatal and 20 serious. Counting every road in the area, 1,383 collisions are recorded within 3 miles. That ranks it 29 of 554 UK junctions we hold collision records for.
Live incidents, roadworks and delays for the whole M25, updated every 5 minutes from National Highways.
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