Number of accidents causing serious delay in 1992: 403.
Most likely circumstances for accident: travelling clockwise, in May, between junctions 27 and 28.
Busiest section: between junctions 13 and 14.
Worst congestion spots: Junctions 15 to 16, junctions 7 to 8
at breakfast time, junction 10, junction 25, junction 28
Worst congestion point according to AA Roadwatch: Junctions 1 to 31 inclusive.
Worst crash: A 26-vehicle pile-up in 1984, in which nine were killed.
Traffic flow: Built to carry 88,000 vehicles a day, it is now used by more than 200,000. A further increase of up to 142 per cent has been predicted by 2025.
Cost of latest plan for widening: pounds 2.8bn (at 1991 prices), with collateral damage to 81 wildlife sites, 47 ancient woodlands and 10 Sites of Special Historic Interest.
Four levels of operating condition: free flow, smooth heavy flow (50-60mph), unstable heavy flow (30-50mph plus tailbacks), broken-down flow.
Police nickname: The Magic Roundabout.Reuse content