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M25 J21A at 11:46 on Monday 12 October: 2 nearby · closure planned from 22:00.
Straight from National Highways, re-checked every 3 minutes while this page is open.
Location from the National Highways junction reference. Nearest towns: Radlett, Watford, St Albans, Hemel Hempstead.
Wider area: counting every road within 3 miles — local streets, A-roads, everything — 1,218 collisions are on record, 20 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 J21A. 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 J21A → 16 of 33 junctions on the M25 · see where it ranks nationallyM25 J21A is at St Albans & Bricket Wood. National Highways signs it as M1 North. The nearest town is Radlett.
Not at M25 J21A itself as of 11:46. Nearby, National Highways report: The M25 anti-clockwise exit slip at junction J21. Resurfacing. All lanes will be closed. The hard shoulder, lanes one and two will be closed. From 22:00 on 15 October 2026 to 05:00 on 16 October 2026… (Anticlockwise) (1 junction away).
Not right now. Planned: M25 Clockwise Jct 21A to Jct 22 carriageway and slip road closure, from 22:00 until 05:30 Tue 13 Oct.
Police STATS19 records show 92 collisions on the M25 within 2 miles of J21A, including 0 fatal and 18 serious. Counting every road in the area, 1,218 collisions are recorded within 3 miles. That ranks it 95 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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